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cij911
Two Feathers

23 Posts

Posted - 11 Nov 2019 :  09:52:24 AM  Show Profile  Reply with Quote
I have a 1965 GTO tri power with upgraded c5 corvette brakes (need a little vacuum)

- 400 cubic inch block from a 68' Catalina (believe it to be stock / stock replacement). Currently running #14 heads (low compression) - decent torque but not close to what I want.
- #16 heads -- high compression but will run 91 + 2 cans of Torco per tank (or use a cam that bleeds of a bit of compression?)
- Tri power
- Dougs headers

Transmission & Rear
- Muncie 4 speed
- 3.55 differential

(I do have power disc brakes but could use a vacuum can if necessary)


What I am looking for - performance. I like the to drive the car. I enjoy winding it through the gears, heel and toe downshifting, and trail braking in the turns. I don't want a motor that is dead below 3k RPM, but I also don't want a cam that is dead by 4500 either. I'd like a cam that pulls hard to 5500+ rpm, but I can still be cruising around at 2500 with plenty of pep on hand.


The cams I am considering are:

1. Factory cam - 068....seems to perform well, requires nothing fancy in the way of setup or springs, and gentle on the valve train

2. Lunati Voodoo 703 (268/276) or 704(276/284) cam... these were one of the last designs of famed cam designer Harold Brookshire and he felt it was his best....opens fast, but closes more gently than others...how the cam is degreed is essential

3. Crower 60242 or 90619....based in San Diego (less than 1 hour from me) and appear to be liked by several of the top builders....

Then regarding the #16 heads, how much can be gained from porting vs. just doing a gasket match on intake and exhaust? My concern is I can quickly start spending $$$ on the heads and for just a little more get complete KRE aluminum heads that will outperform in every way.

Thanks

Chris

65' GTO Convertible Tri Power

Steve C.
Chief PONTIAC

2100 Posts

Posted - 11 Nov 2019 :  11:00:43 AM  Show Profile  Reply with Quote
Keep in mind a wider lobe separation will:
Reduce Maximum Cylinder Pressure
Decrease Cranking Compression
Decrease Effective Compression
Idle Vacuum is Increased

The Crower cams typically have a 112 LSA. Many have a 110. And always keep in mind you can easily have a custom cam ground from ANY company to alter their published catalog specifications. Also in my opinion with a new cam change the valve springs unless you are positive they are not old. That and make sure they have adequate pressure to suit the intended cam choice.

Also for interest go here and note how the amount of seat timing (advertised duration) will effect your dynamic compression and other considerations:
http://www.wallaceracing.com/Calculators.htm

You may have to use one calculator to get the intake and opening valve affects then use them on another calculator.

Edited by - Steve C. on 11 Nov 2019 11:05:00 AM
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 11 Nov 2019 :  1:41:28 PM  Show Profile  Reply with Quote
The 068 with a set of melling 1.65 rockers would do ok with some slight head work on the 16s. Nothing fancy but that combo with compression into mid to upper 9s will out perform a lot of other shelf cams, especially with some rockers that give it some lift.

I assume the last Crower on the list was 60919. With 16 heads and flat tops, that would be a good choice with a bigger ratio rocker arm and more head work. It is about as big as you will want to do with something that Crower has for the vacuum brakes. With 1.5s I would look at the 60243. It would be better than the 60242 if the compression ends up close to 10 scr. About 9.5 is all I would want to do with the 242 in a 400. With some port work I would personally do the 919,1.65s or the 243 with 1.5s if something off the shelf from Crower. If your close to HQ they might have something custom that might fit a little better yet. On flat tappet Pontiacs with adjustable valve terrain I really like the Rhoads vmax and VPro lifters super lubes and taylor the lash to your driving tastes. They perform on the top end like a solid lifter and can be set to go from doing nothing and quiet as a mouse at idle to taking a bunch of valve timing off the cam and sounding like a sewing factory with a 2bbl type cam idle. Another $80 to have those options over crowers cam saver lifter has always seem like it was worth it to me.

As far as I know Crower really does not appear to have put much development into their flat tappet cam lines for a number of years. They mostly appear to be just basic symmetrical cams with different acceleration rates. From that aspect, I prefer Harold Brookshires work when it comes to cams, especially flat tappet stuff, his finger prints are all over the world of cams across a bunch of companies. Most of his stuff we have done are custom Bullet/Ultradyne profiles. But if one of the off the shelf voodoos are a good fit they are in kind of a class of their own for max lift using a .842 lifter with good valve control. Howards cams has some of Brookshire later profiles too.

As fair what is possible with a 16 head. They have deep valve pockets and have a ton of flow potential over just gasket matching. It probably does all add up and get pricey, I can totally see the reason why people jump ship and go aluminum. I have done extensive porting on 16s, I have one set that would give a kre set a run for the money. All comes down to what you can do your self or who you can find to work them over.
Jay

Edited by - Corncob2061 on 11 Nov 2019 1:57:48 PM
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tjs44
Crazy Horse

USA
650 Posts

Posted - 11 Nov 2019 :  1:48:45 PM  Show Profile  Reply with Quote
As they great engine builder,Joe Sherman once told me,HP is in the heads.The better the head the less cam needed to meet a target HP.Tom
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 11 Nov 2019 :  2:12:03 PM  Show Profile  Reply with Quote
Stock or stock replacement 400. Probably should stay kind of conservative or you will be going a lot deeper into the engine very quickly. The 068 with some mildly worked of 16s might be a good plan.

If 1.5 hrs from Crower HQ. Pump gas Pontiac combos down that direction Tom reigns King.
Jay

Edited by - Corncob2061 on 11 Nov 2019 2:12:22 PM
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 11 Nov 2019 :  4:18:02 PM  Show Profile  Reply with Quote
"As far as I know Crower really does not appear to have put much development into their flat tappet cam lines for a number of years"

X2

"Most of his stuff we have done are custom Bullet/Ultradyne profiles. "

X2 again !

http://www.bulletcams.com/
Talk to Tim

Or keep it simple but generic....

"The 068 with a set of melling 1.65 rockers would do ok with some slight head work on the 16s. Nothing fancy but that combo with compression into mid to upper 9s will out perform a lot of other shelf cams, especially with some rockers that give it some lift."

X2 with the additional valve lift !

Edited by - Steve C. on 11 Nov 2019 4:20:27 PM
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cij911
Two Feathers

23 Posts

Posted - 11 Nov 2019 :  5:22:46 PM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

Stock or stock replacement 400. Probably should stay kind of conservative or you will be going a lot deeper into the engine very quickly. The 068 with some mildly worked of 16s might be a good plan.

If 1.5 hrs from Crower HQ. Pump gas Pontiac combos down that direction Tom reigns King.
Jay



Jay, can you explain this a bit more? The motor burns no oil, no smoke on acceleration or deceleration, so I believe the rings are sealing well.

I suspect the CR will be 10 - 10.5:1 range with the #16 heads.

65' GTO Convertible Tri Power
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cij911
Two Feathers

23 Posts

Posted - 11 Nov 2019 :  5:28:40 PM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

Stock or stock replacement 400. Probably should stay kind of conservative or you will be going a lot deeper into the engine very quickly. The 068 with some mildly worked of 16s might be a good plan.

If 1.5 hrs from Crower HQ. Pump gas Pontiac combos down that direction Tom reigns King.
Jay



Sorry, who is Tom? Where is he/ how do I contact him ? Thanks

Chris

65' GTO Convertible Tri Power
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 11 Nov 2019 :  7:08:04 PM  Show Profile  Reply with Quote
Tom is tjs44 a couple posts up. I believe he as one street car with a 068 cam and runs several great running street Pontiacs. Also a manual trans guy..

It is a good sign that it runs good and does not use oil.. It is more what is currently inside the engine if it is completely stock. Stock cast pistons, stock cast rods, stock rod bolts, and the stock oil pump. Usually when engines get major performance upgrades with high flowing heads and a cam to match, add a set of forged piston, forged rods, good rod bolts and oiling upgrades to help it stay together. I have ran some pretty high hp stuff with cast pistons and stock rods with arp bolts. But we always have some extra oil clearance, 3/4 or full groove mains and a high volume oil pump. Just trying to point out that you should keep that stuff in mind.

Steve C has his T/A listed over on the torque and power section of this site. Go check it out and you will see all the upgrades inside on the short block and you will see what I mean. Making big power with big upgrades is a snow ball away from an avalanche.

Do you have some 16s or looking for some? Pontiac over rated their compression a fair amount. Usually by a half of a point. Probably either side of 10:1. Jay

Edited by - Corncob2061 on 11 Nov 2019 8:00:05 PM
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 11 Nov 2019 :  7:26:45 PM  Show Profile  Reply with Quote
I come up with 9.89 SCR with a 72 cc 16 head, .042 thick head gasket, 6.7 cc valve releif with the piston .025 from the deck. It is probably a little lower than that yet if you account for the chamfers on the top edges of the cylinders. I think those add 2 cc. Probably close to 9.7- 9.8 scr. Unless you have the 8 valve releif pistons. That knocks it down to low 9s even with a 72 cc head. A 68 low performance engine could have those 8vr pistons. Hopefully it has the better 4 relief pistons. You could pull a spark plug out and shine a light on the pistons and probably see what is in it. Jay
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 11 Nov 2019 :  11:05:17 PM  Show Profile  Reply with Quote
"Making big power with big upgrades is a snow ball away from an avalanche."

That cracked me up, but some truth to it. For a long time I was single and no family to support, and also before retirement set in. I personally spent more money on items that many would not. I was very fortunate that I could afford it, and often many items
not really needed on a street car. One good example that was overkill... a T&D shaft mounted rocker system. Jim Butler screwed up a block I sent him, instead of a refund I took credit... I really didn't need a shaft system for that build. Also the Carrillo steel rods were previously used in two prior engines. And really in truth Pro-Gram Engineering 4 bolt main caps may have not been necessary. Or the MSD ignition system. Etc, etc.

http://www.pontiacstreetperformance.com/psp/rebuild455sc2003.html


.

Edited by - Steve C. on 12 Nov 2019 10:21:22 AM
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cij911
Two Feathers

23 Posts

Posted - 12 Nov 2019 :  10:02:57 AM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

Tom is tjs44 a couple posts up. I believe he as one street car with a 068 cam and runs several great running street Pontiacs. Also a manual trans guy..

It is a good sign that it runs good and does not use oil.. It is more what is currently inside the engine if it is completely stock. Stock cast pistons, stock cast rods, stock rod bolts, and the stock oil pump. Usually when engines get major performance upgrades with high flowing heads and a cam to match, add a set of forged piston, forged rods, good rod bolts and oiling upgrades to help it stay together. I have ran some pretty high hp stuff with cast pistons and stock rods with arp bolts. But we always have some extra oil clearance, 3/4 or full groove mains and a high volume oil pump. Just trying to point out that you should keep that stuff in mind.

Steve C has his T/A listed over on the torque and power section of this site. Go check it out and you will see all the upgrades inside on the short block and you will see what I mean. Making big power with big upgrades is a snow ball away from an avalanche.

Do you have some 16s or looking for some? Pontiac over rated their compression a fair amount. Usually by a half of a point. Probably either side of 10:1. Jay



Thanks I connected with Tom yesterday and hope to discuss further! Super helpful guy!

I already have a nice set of un-ported #16 large valve heads with stainless valves (on exhaust IIRC) and upgraded springs and 7/16 studs. A neighbor is telling me to just slap the heads on as is and install a good HFT cam, new lifters, 1.5 roller rockers, timing chain, and possibly push rods and call it a day.

This is a weekend toy for me and I am just trying to get the car closer to where it would have been from the factory (power wise). The 400 with the #14 heads is weak :). That said, I really don'y want to get into a fully built motor, $1500+ on head work or $2500 on KRE D ports, unless of course I break something :).

65' GTO Convertible Tri Power
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 12 Nov 2019 :  12:26:22 PM  Show Profile  Reply with Quote
If necessary you can always consider a vacuum pump for your power brakes.

https://leedbrakes.com/i-23439163-electric-vacuum-pump-kit-black-bandit-series.html

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cij911
Two Feathers

23 Posts

Posted - 13 Nov 2019 :  7:21:25 PM  Show Profile  Reply with Quote
quote:
Originally posted by Steve C.

If necessary you can always consider a vacuum pump for your power brakes.

https://leedbrakes.com/i-23439163-electric-vacuum-pump-kit-black-bandit-series.html





I already have it plumbed and ready to use should I need it....Thanks

cij

65' GTO Convertible Tri Power
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cij911
Two Feathers

23 Posts

Posted - 15 Nov 2019 :  08:57:48 AM  Show Profile  Reply with Quote
Any other recommendations on cam for a 400 w/ #16 heads (SCR ~10:1) ? I have been told by two cam manufacturers to NOT go with 1.65 rocker arms - something about changing the effective design of the cam (??). So my plan was to use 1.5 roller rockers. Thanks

65' GTO Convertible Tri Power
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 15 Nov 2019 :  11:20:49 AM  Show Profile  Reply with Quote
Main thing to watch with the bigger rockers is the intensity of the cam and the lift. The 30 degree intakes seat struggle with valve control with some aggressive profiles with 1.5s. 1.65s just make it worse, you need adequate seat pressure. Plus the rockers add 1-2 degrees of duration to the seat timings and 4-5 to the .050 numbers. If you account for that there is no reason not to do the 1.65s so long and the push rod clears the head on the intake ports. BBC has 1.7 ratio from the factory, so does a bunch of fords. Some even used 1.75s from the factory like 348 and 409 Chevy and in-line 6 chevys.

Compcams magnum profiles work good, the 276ah10 or the 280ah10. But I would widen the lsa out to 112 instead of 110 if you get close to 10:1 compression on the 276ah10. The last two digits on those indicates the lsa. The 280ah-10 would probably work at 110 though in a 400. 112 with some advanced would be better imho.

This Howards cam would be ok in a 10:1 400 with 16s. I would run it before I ran a actual melling 041 cam (spc-8)in a 400. It would be a step over the crower 60919 or the 60243 if your looking to blead compression off. I am not to sure what your dealing with were you at, which is why Tom is a good contact. I would give it a fair amount of advance. Degree it in of 108 icl. 285/295 231/241 114 lsa .48/.47

https://www.summitracing.com/parts/hrs-410051-14/make/pontiac

The summit 2802 or similar grind (jegs, melling, ect) would also be a good choice if you find your compression 10:1 or lower in your 400. It is 298/308 at .004 tappet, summit advertised it at 282/292 224/234 114 lsa .476/.496. I think that is close to the specs anyway (actual is 286/296 at .006 if I recall correctly). Specs vary some depending on were you look. It is a good candidate for 1.65 rocker to. It is also a good value price wise. With 1.65s it would likely out run the 60243 from Crower. We have ran 20 or so of those profiles like the 204/214/224/234 cams. But lately I have done all Ultradyne or Bullet profiles. A few compcams in the mix. Most of the lunati, UD and compcams hfts are more advances design wise.

Several Ultradyne profiles to pick from too, if you want to talk to someone that has a lot of experience talk to them. I think Steve posted it earlier, it is Tim at Bullet. His extension comes up when you dial their number on the answer service. I would probably do the 288/296 231/239 on a 110 lsa. But they are good at picking pump gas cams for Pontiacs. That 288/296 is rated at .0045, subtract 6 off the seat numbers to compare it in .006 to compcams or the others (282/290). It is a very close cam specs and profile design to that comp 280ah10. Jay

Edited by - Corncob2061 on 15 Nov 2019 11:41:41 AM
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 15 Nov 2019 :  12:03:19 PM  Show Profile  Reply with Quote
Higher Ratio Rocker Arms
by Jim Hand, July 1999

http://www.pontiacstreetperformance.com/psp/RockerArms.html
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 15 Nov 2019 :  12:04:10 PM  Show Profile  Reply with Quote
Shorten cliffs notes version of the last thread

Best value in a 9.5-10 400....

Summit 2802 which is a spirited version of the hotter ram air 744 ra 3 cams. Use it with melling 1.65 rockers (also a best value)Then use Crower 68404 valve springs. The rockers run close to 1.6 ratio, so just over .5 lift. Jay

Edited by - Corncob2061 on 15 Nov 2019 12:11:23 PM
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cij911
Two Feathers

23 Posts

Posted - 16 Nov 2019 :  10:13:55 AM  Show Profile  Reply with Quote
Thanks !!

65' GTO Convertible Tri Power
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cij911
Two Feathers

23 Posts

Posted - 17 Nov 2019 :  09:22:56 AM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

Shorten cliffs notes version of the last thread

Best value in a 9.5-10 400....

Summit 2802 which is a spirited version of the hotter ram air 744 ra 3 cams. Use it with melling 1.65 rockers (also a best value)Then use Crower 68404 valve springs. The rockers run close to 1.6 ratio, so just over .5 lift. Jay



Any idea who designed the Summit 2802 cam and who actually manufacturers Summit's camshafts ?

Also, I suspect I will be running over 10:1 compression, so would that still make the 2802 a good choice? (Summit says it wants 9.5:1 or greater, so it appears anything over 10:1 would be fine as long as the fuel is good.)

What about the 041 vs 068 ? I have read mixed perspectives on the 041 in a 400 and the need to run special lifters and 1.65 rockers to truly beat the 068 (1/4 mile) and even then not by a lot.

My OCD has taken over and I am obsessing over something that will likely mean little.....

65' GTO Convertible Tri Power

Edited by - cij911 on 17 Nov 2019 09:59:52 AM
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tjs44
Crazy Horse

USA
650 Posts

Posted - 17 Nov 2019 :  10:40:03 AM  Show Profile  Reply with Quote
Nothing is going to make 10-1 very safe IMO with our crap pump gas.Think about it,we put in bigger cams to make more HP,more HP comes from cyc pressure.Sure big cams bleed off cyc pressure at low RPMs but what happens when the "engine comes on to the cam"Tom
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cij911
Two Feathers

23 Posts

Posted - 17 Nov 2019 :  11:24:50 AM  Show Profile  Reply with Quote
quote:
Originally posted by tjs44

Nothing is going to make 10-1 very safe IMO with our crap pump gas.Think about it,we put in bigger cams to make more HP,more HP comes from cyc pressure.Sure big cams bleed off cyc pressure at low RPMs but what happens when the "engine comes on to the cam"Tom



Tom - thanks I've been meaning to call you.....I plan on running ~98-100 octane.

Chris

65' GTO Convertible Tri Power
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 17 Nov 2019 :  11:28:16 AM  Show Profile  Reply with Quote
Have you gone to any of the calculators, again for interest?

Effective Compression Ratio Calculator
http://wallaceracing.com/eff-cr.php

Others as well.
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 17 Nov 2019 :  5:03:55 PM  Show Profile  Reply with Quote
More than likely Camshaft Machine Company (CMC) grinds the summit cams. If I recall correctly those 204/214/224/234 cams were originally designed by General Kinetics????? CMC has went through several owners. Crane owned them for a while then sold them. So crane did the summit grind via CMC. Federal Mogul owned CMC for a few year. Not sure who owns them now. If I recall correct CMC ground the melling cams, or melling subs that out too CMC.

The term bigger cam has different meanings.

A bigger cam to build more cylinder pressure, sometimes at almost the same rpm or through the same power band to increase HP.

A bigger cam may mean the same or less cylinder pressure at a higher rpm to increase HP, which people call bleeding off compression.

Look at it this way with this equation

BHP = BMEP X Displacment X RPM / 792000

BHP is brake HP

BMEP is the mean or average effective cylinder pressure

You can make HP several ways, but it is dependent on one three inputs: BMEP, displacement, or RPM.

For the bigger cams in a fixed CID engine, the goal is the raise the HP by either raising the BMEP number and keep the RPM down to keep it streetable. Or another cam might or drop the BMEP and raising the RPM to get HP. A higher output engine might use both.

98 to 100 octane it will not matter much what cam you use at 10:1 scr. People usually have good results on pump gas with the summit 2802 in a 400 up to 9.5-10:1 compression. IMO, the 041 is to much cam in a stock flow d port in a 400. It would be better to go with the 744 or the 068 unless your going to do some porting on the heads. Best results match up the cid, cam, SCR and the head flow.. A bigger cam might blead off compression to run higher compression, but if you do not have the head flow you gain very little and just make it less streetable. Jay



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cij911
Two Feathers

23 Posts

Posted - 17 Nov 2019 :  9:18:01 PM  Show Profile  Reply with Quote
quote:
Originally posted by Steve C.

Have you gone to any of the calculators, again for interest?

Effective Compression Ratio Calculator
http://wallaceracing.com/eff-cr.php

Others as well.



Steve, honestly when I play with the Wallace calculators I seem to get very different numbers for CR (more like 10.5-10.75:1) vs others stating mid to upper 9's. I haven't begun playing with cam calculators as I have no idea on cam design. I'll take a look for giggles :).

65' GTO Convertible Tri Power
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cij911
Two Feathers

23 Posts

Posted - 17 Nov 2019 :  9:19:49 PM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

More than likely Camshaft Machine Company (CMC) grinds the summit cams. If I recall correctly those 204/214/224/234 cams were originally designed by General Kinetics????? CMC has went through several owners. Crane owned them for a while then sold them. So crane did the summit grind via CMC. Federal Mogul owned CMC for a few year. Not sure who owns them now. If I recall correct CMC ground the melling cams, or melling subs that out too CMC.

The term bigger cam has different meanings.

A bigger cam to build more cylinder pressure, sometimes at almost the same rpm or through the same power band to increase HP.

A bigger cam may mean the same or less cylinder pressure at a higher rpm to increase HP, which people call bleeding off compression.

Look at it this way with this equation

BHP = BMEP X Displacment X RPM / 792000

BHP is brake HP

BMEP is the mean or average effective cylinder pressure

You can make HP several ways, but it is dependent on one three inputs: BMEP, displacement, or RPM.

For the bigger cams in a fixed CID engine, the goal is the raise the HP by either raising the BMEP number and keep the RPM down to keep it streetable. Or another cam might or drop the BMEP and raising the RPM to get HP. A higher output engine might use both.

98 to 100 octane it will not matter much what cam you use at 10:1 scr. People usually have good results on pump gas with the summit 2802 in a 400 up to 9.5-10:1 compression. IMO, the 041 is to much cam in a stock flow d port in a 400. It would be better to go with the 744 or the 068 unless your going to do some porting on the heads. Best results match up the cid, cam, SCR and the head flow.. A bigger cam might blead off compression to run higher compression, but if you do not have the head flow you gain very little and just make it less streetable. Jay







Jay, thank you very much. Do you like the 2802 over the Lunati 703 or 704 for a higher compression 400?

65' GTO Convertible Tri Power
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 18 Nov 2019 :  08:57:23 AM  Show Profile  Reply with Quote
The 703 is more of a 9-9.5 scr cam in pump gas 400. My opinion it is among the best hft cams available in a street 400 for 9.0-9.5 scr. Someone that knows what they are doing could go 10:1 in a 400 with the 704. Both those cams with the 110lsa are just like what Tom described, when they get in their power band they pull harder and the bmep will spike and test what ever fuel your running if it is questionable. The summit 2802 has a 114 lsa. It does not have the big mid range push and has smoother power band. I like the summit 2802 with 1.65s in the 9.5-10 scr range. Very good power with exhaust manifolds. If you do not mind a snotty idle, running headers or RA manifolds, and did a little bowl work on the heads, plus a good induction with 1.5s I like the 704.

If your serious about a lunati you might want to contact Paul Carter in Arizona. Then buy it through him. I would not doubt if he has done the exact combo your think of. Jay


Edited by - Corncob2061 on 18 Nov 2019 09:23:27 AM
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 18 Nov 2019 :  10:35:51 AM  Show Profile  Reply with Quote
"If your serious about a lunati you might want to contact Paul Carter in Arizona. Then buy it through him."

X2

He has done a lot of dyno testing with Lunati Voodoo cams. And as I first mentioned in my first post he can get them custom ordered with a wider lobe separation if necessary. He has done it with them. Also as I've pointed out before on this site Paul also recommends more seat pressure than Lunati suggests in their catalog, this based on his testing. His contact number (520) 409-7236


.
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 19 Nov 2019 :  06:10:58 AM  Show Profile  Reply with Quote
Number Of Cylinders: 8
Bore: 4.120
Stroke: 3.750
Head Chamber (cc's): 72
Valve Relief (cc's): 6.6
Gasket Thickness: .039
Gasket Bore Diameter: 4.300
Deck Height: .020

Static compression ratio 9.88

This with a Fel Pro 1016 head gasket. I have no clue what the stock piston valve relief volume is on a '68 Catalina 400 engine. I left it at the 6.6 as on the Wallace calculator. But a Speed Pro 400 replacement piston is 10.5 cc's. That would make the compression lower. And this presumes the chamber volume is as published, that should always be verified.

Edited by - Steve C. on 19 Nov 2019 07:22:52 AM
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 19 Nov 2019 :  07:22:20 AM  Show Profile  Reply with Quote
For interest only compare these two cams using the calculator linked. Note the difference in the dynamic compression ratio, dynamic cranking pressure and the amount of overlap between the two. Note how duration at .006 tappet lift and lobe separation makes a difference. The overlap period has a profound influence on the running characteristics of the engine. It effects both the low speed and high speed characteristics. It may not be exact but for this exercise use 10:1 static compression ratio. Pick a Target Altitude where you live, if unknown a close local airport has that information. Use zero boost.

Voodoo 703
268/276
110 LSA/106 ICL
Intake valve closes at 60 degrees ABDC
52 degrees overlap

Crower 60243
284/290
112 LSA/108 ICL
Intake closes at 70 degrees ABDC
63 degrees overlap

Due note that the intake duration at .050 tappet lift they are within one degree of each other. 227 & 228
The Vooddo lobe has more beneficial valve lift.

http://www.wallaceracing.com/dynamic-cr.php??

Edited by - Steve C. on 19 Nov 2019 07:26:15 AM
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 19 Nov 2019 :  07:42:59 AM  Show Profile  Reply with Quote
Many don't even give the dynamic compression ratio a thought.

I've seen a tech article in a magazine that suggested 7.5 - 8.5 DCR best at 91 octane or better. Another suggested desirable for a street engine staying below 8.25 is probably best for trouble free motoring.

One popular site suggests 160-180 cranking pressure for pump gas street car. High Performance Pontiac article suggested 170-185.

Another source, max cranking pressure for 92 octane pump gas car is roughly 190 psi, unless very good modern chamber design.

Just conversation around the coffee table here, information provided does not represent a endorsement. And unless specified it is not based on personal experience and offered for general interest.

Edited by - Steve C. on 19 Nov 2019 07:45:22 AM
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cij911
Two Feathers

23 Posts

Posted - 19 Nov 2019 :  09:33:11 AM  Show Profile  Reply with Quote
Steve - Thank you so much!!! Super helpful - I was not putting anything in the gasket bore diameter (duhhh). I will take a picture of the pistons and hopefully someone will recognize the design (I believe they are cheap replacements.)

Currently my cranking pressure is ~150 psi (with low compression #14 heads and unknown cam).

I will play with the calculator and the two cams provided and see what the results look like. Thanks again for sharing a bit of your knowledge and time!

65' GTO Convertible Tri Power
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cij911
Two Feathers

23 Posts

Posted - 19 Nov 2019 :  09:38:58 AM  Show Profile  Reply with Quote
This is what I got from the 703 Voodoo:

Static compression ratio of 10:1.

Effective stroke is 3.01 inches.
Your dynamic compression ratio is 8.22:1 .
Your dynamic cranking pressure is 166.76 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 8.12 :1.
V/P (Volume to Pressure Index) is 161

VS. the crower 60243:

Static compression ratio of 10:1.
Effective stroke is 2.75 inches.
Your dynamic compression ratio is 7.60:1 .
Your dynamic cranking pressure is 150.26 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 7.50 :1.
V/P (Volume to Pressure Index) is 132

So it would appear both cams fall in the range of being OK, but the Voodoo has more DCR. I know there are so many components that will make a cam perform, but I would suspect the Voodoo 703 would have a broader power band (?).

65' GTO Convertible Tri Power

Edited by - cij911 on 19 Nov 2019 09:43:19 AM
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 19 Nov 2019 :  10:44:27 AM  Show Profile  Reply with Quote
I used the Crower 60243 only because it is a popular often used cam in 400 combinations, and has the "same" .050 duration as the Voodoo cam. Please note this not a recommendation by me for it or a Crower product.
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cij911
Two Feathers

23 Posts

Posted - 19 Nov 2019 :  10:54:06 AM  Show Profile  Reply with Quote
Steve, super helpful and very much appreciated. Which cam design / manufacturer do you like? Do you have an opinion on some of the "more advanced" cam profiles with fast opening / closing ? I am guessing the factory (e.g. 068) cams open and close more slowly and would be easier on the valve train.

65' GTO Convertible Tri Power
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 19 Nov 2019 :  11:36:57 AM  Show Profile  Reply with Quote
A fwiw, when I stated many don't even give the dynamic compression ratio a thought. I meant to add on many don't give it a thought as they don't consider it a valid parameter to figure octane requirements. Take all this with a grain of salt.

Chris the last hydraulic flat tappet cam I used was 29 years ago when like many I threw darts at a catalog to make a choice. It was a generic Comp Magnum 280H for my original RAIII 400 engine. After it the only time I used a "off the shelf" catalog cam was with the Crower 60452 solid roller cam. Since then all the others have been custom solid roller cams. Once I get a general idea of what I need (or think I need as I'm not a engine builder or cam expert) I then call the cam manufacture and work directly with them with my ideas and get a custom made cam. Over the years I've used more UltraDyne lobes than anything, at first direct with Harold Brookshire. Later when he was at Lunati. I've also worked with Chris Mays at Comp for two cams and Dave Crower for one. Now years later we have been using cams from Bullet Racing, currently with a UltraDyne MSP solid roller. Jay here on the board has also been working with Tim at Bullet for custom cams.

Unlike many I believe in the theory a quick opening and closing cam will provide better low end performance than one that is slower opening. And if necessary narrow lobe separations don't bother me. And I do not mind a rowdy idle quality :)

Same thing applies to torque converters, I have custom units built specific for each application. They can be one of the best bangs for your buck !


Edited by - Steve C. on 19 Nov 2019 11:48:40 AM
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tjs44
Crazy Horse

USA
650 Posts

Posted - 19 Nov 2019 :  12:38:19 PM  Show Profile  Reply with Quote
Paralysis by analysis!Tom
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 19 Nov 2019 :  12:44:21 PM  Show Profile  Reply with Quote
Throw the Summit 2802 in there and get it done.

And Tom has a cam guru he works with at Comp Cams, one of the best in the country ! Same fellow the owner of our local speed shop worked directly with.



Edited by - Steve C. on 19 Nov 2019 12:47:05 PM
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tjs44
Crazy Horse

USA
650 Posts

Posted - 19 Nov 2019 :  1:17:38 PM  Show Profile  Reply with Quote
Steve,he has only talked me out of my own choice of lobes once on one lobe in the last 15 years or so.That was the cam in the 428 RA V engine.For what I do with my engines and not trying to squeeze the last single HP out of a street engine my fall back is still the Magnum high lift hyd roller lobes.The last flat tappet cam I used was a 068 I put in my 421 HO engine for my 62 GP.Pretty much all the last 4-5 engines I have built I break them in a the dyno or run stand.Do a pumping test and then advance or retard the cam to get me to my target 180 number for our 91 pump gas.Has never failed me for good driving habits with very high geared stick shift cars.My 421 62 GP is 2.68 final gear.My 63 421 SD lemans is 2.58 and my 69 455 bird soon to be 428 RA V is 2.19.All these engine run good from about 1500 in final gear without having to back down a gear.Myself as with you have used trial and very few errors to help me pick cams for what we do,you for racing and me for just hipo street cars.Tom
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 19 Nov 2019 :  5:16:44 PM  Show Profile  Reply with Quote
Tom, Since I built my current 505 about 12 years ago my car been on the track only twice, or maybe three times and for interest only. It's now street only. My car is actually very driveable, especially with the overdrive transmission. And with only 10:1 compression. The only major change has been the addition of Holley multiport fuel injection, which actually did very little to improve driveability. But with fuel injection heat related carburetor issues were eliminated and it has only a slightly better idle quality.
I have no future changes or projects planned, after 30 years of owning the car I'm done.




Edited by - Steve C. on 19 Nov 2019 5:27:44 PM
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 19 Nov 2019 :  6:42:12 PM  Show Profile  Reply with Quote
quote:
Originally posted by cij911

This is what I got from the 703 Voodoo:

Static compression ratio of 10:1.

Effective stroke is 3.01 inches.
Your dynamic compression ratio is 8.22:1 .
Your dynamic cranking pressure is 166.76 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 8.12 :1.
V/P (Volume to Pressure Index) is 161

VS. the crower 60243:

Static compression ratio of 10:1.
Effective stroke is 2.75 inches.
Your dynamic compression ratio is 7.60:1 .
Your dynamic cranking pressure is 150.26 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 7.50 :1.
V/P (Volume to Pressure Index) is 132

So it would appear both cams fall in the range of being OK, but the Voodoo has more DCR. I know there are so many components that will make a cam perform, but I would suspect the Voodoo 703 would have a broader power band (?).



I will help you decipher your numbers here. I use DCR as one of the parameters for picking cams. I am also an Engineer, so using calculators and equations are routine.

1. A street car using 91 octane starts at a dcr target of between 6.8-7.5 for most engines with cast iron heads and flat tappet cams. This is for using ONLY .009 lift out at the valve. Which is .006 tappet with 1.5 rockers. If I do not know what that number is I check the spec off the actual cam or talk to a cam rep.

2. Depending on the intensity of the cam, you work from different ends of the range. For a cam like a 041 or one of the Summits which run about 62* from .006 to .050, start at the bottom of the range. For an XE or an aggressive cam start at the top, closer to 7.5. The bigger the cam the higher you can go on the dcr, the better the E/I ration or bigger durations on the exh, go higher too. But you almost never go past 7.5 dcr with cast iron heads on pump gas.

Notice the 703 lunati is 8.22 dcr in a 10:1 400. Cranking pressure of around 166. 166 is likely roughly 30 low from actual because of the profile of that cam. If you work backwards 5 psi of cranking pressure is 1 octane point. Adjust the dcr to 7.5, record the cranking pressure and find the difference.

Cranking pressure (10:1). - cranking pressure(to get the dcr=7.5) = adjusted cranking pressure

Adjusted cranking pressure /5=min octane increase

Required octane = min octane increase + 91

V/P index is next. I can go into that if you want. This thread might get really long and boring. It is the next step for picking cam. I did not learn this stuff over night either.

Tom and Steve have both done very good picking cams. I keep tabs, best way to learn is from folks that tried thing already.

Edited by - Corncob2061 on 19 Nov 2019 10:44:58 PM
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 19 Nov 2019 :  10:16:31 PM  Show Profile  Reply with Quote
Also worth considering is the actual .006 specs for the lunati 703 is 273/281. The 268/ 276 is the Lunati advertised number. I think they changed the numbers on the current cam card and they no longer say 273/281, just 268/276.

But note what I said a couple posts up. The 703 is one of the best street cams there is in a 9.0-9.5 compression 400 Pontiac. Guess what the dcr is using the .006 tappet rating of 273/281 at 9.5 static compression..right under 7.5 dcr. It is friendlier for pump gas than what it appears looking at the advertised rating. But not friendly enough for 10:1 scr. Which is up past 7.8 dcr.

The Crower 60243 does not have much wiggle room for octane either at 10:1, even though the dcr is right at 7.5. It has decent intensity, but it is not close to that lunati. It has 56*, basically right in the middle between the 2802 and the 703. Which means it will like a dcr closer to 7 than 7.5. It works ok were I am at becuase I add the elevation to the Wallace dcr calculator. I have nearly 1000 feet over you sea level guys. A couple hrs drive and I am at 3000 ft. That makes a difference too. What works here for a cam and compression might not work on the coast. Jay

Edited by - Corncob2061 on 19 Nov 2019 10:34:45 PM
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 19 Nov 2019 :  10:40:48 PM  Show Profile  Reply with Quote
This is not new for Jay but here is some old Lunati information:

https://www.jegs.com/VendorInfo/Lunati/images/lunati-catalog.pdf
pg 175 Pontiac Voodoo lobes

Trying to navigate thru any current Lunati material is very difficult to say the least.

https://www.lunatipower.com/

It has been quite some time ago but when I talked with their tech department they said their website was being updated. And they admitted it left a lot to be desired.
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 19 Nov 2019 :  10:48:07 PM  Show Profile  Reply with Quote
Compcams is staring to get more difficult to navigate to. Looking more and more like the Lunati. I was hoping it would go the other way. Grrr

https://www.compcams.com/

https://www.lunatipower.com/

Edited by - Corncob2061 on 19 Nov 2019 11:02:35 PM
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Steve C.
Chief PONTIAC

2100 Posts

Posted - 20 Nov 2019 :  10:40:08 AM  Show Profile  Reply with Quote
For Comp I just use their Master Lobe Profile catalog

https://www.compcams.com/lobe-catalog
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tjs44
Crazy Horse

USA
650 Posts

Posted - 20 Nov 2019 :  11:21:29 AM  Show Profile  Reply with Quote
Thats what I have used for maybe close to 20 years.Tom
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Corncob2061
Crazy Horse

USA
589 Posts

Posted - 20 Nov 2019 :  11:54:31 AM  Show Profile  Reply with Quote
That is what I use to, I have a physical book. One their old site you could match all there valve terrain components for each particular engine and cam combo Pushrods, rockers, retainers, springs ect ect. That was a really nice feature. Especially for those that do a variety of engines, foreign and domestic. It saved a lot of time, I use to start a lot of searches at comps site. Now that comp and lunati are owned by the same investor group it appears they might be doing some streamlining. It will be interesting now that they own crane to see if it changes. Jay
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cij911
Two Feathers

23 Posts

Posted - 20 Nov 2019 :  7:01:07 PM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

Also worth considering is the actual .006 specs for the lunati 703 is 273/281. The 268/ 276 is the Lunati advertised number. I think they changed the numbers on the current cam card and they no longer say 273/281, just 268/276.

But note what I said a couple posts up. The 703 is one of the best street cams there is in a 9.0-9.5 compression 400 Pontiac. Guess what the dcr is using the .006 tappet rating of 273/281 at 9.5 static compression..right under 7.5 dcr. It is friendlier for pump gas than what it appears looking at the advertised rating. But not friendly enough for 10:1 scr. Which is up past 7.8 dcr.

The Crower 60243 does not have much wiggle room for octane either at 10:1, even though the dcr is right at 7.5. It has decent intensity, but it is not close to that lunati. It has 56*, basically right in the middle between the 2802 and the 703. Which means it will like a dcr closer to 7 than 7.5. It works ok were I am at becuase I add the elevation to the Wallace dcr calculator. I have nearly 1000 feet over you sea level guys. A couple hrs drive and I am at 3000 ft. That makes a difference too. What works here for a cam and compression might not work on the coast. Jay



Thanks Jay!

65' GTO Convertible Tri Power
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tjs44
Crazy Horse

USA
650 Posts

Posted - 20 Nov 2019 :  8:35:24 PM  Show Profile  Reply with Quote
The master lobe profile catalog is as the title says,ONLY lobes and their specs.No springs,retainers etc at all or recommendations.Tom
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tjs44
Crazy Horse

USA
650 Posts

Posted - 20 Nov 2019 :  8:38:10 PM  Show Profile  Reply with Quote
Chris,some of the local pontiac guys will be meeting for breakfast at the Enderly center at 8 this Sunday.17th street and the 55 freeway if you can make it.Not sure what car I will drive yet.Tom
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cij911
Two Feathers

23 Posts

Posted - 21 Nov 2019 :  7:27:24 PM  Show Profile  Reply with Quote
quote:
Originally posted by tjs44

Chris,some of the local pontiac guys will be meeting for breakfast at the Enderly center at 8 this Sunday.17th street and the 55 freeway if you can make it.Not sure what car I will drive yet.Tom



Tom, Thanks for the invite! I'll be there with my GTO and a buddy that is a Pontiac nut.

65' GTO Convertible Tri Power
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