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phil400
Crazy Horse

Canada
504 Posts

Posted - 01 Nov 2017 :  9:17:50 PM  Show Profile  Reply with Quote
I?m looking the XE268 or better yet the Lunati version of the same cam, but I?d like to keep valve lift around .450?. Will comp or Lunati grind it?

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive.
77 T/A sold
85 Monte Carlo SS sold
83 Mustang GT sold
"Let me tell you what Melba toast is packing"

tjs44
Crazy Horse

USA
527 Posts

Posted - 02 Nov 2017 :  09:16:15 AM  Show Profile  Reply with Quote
You need to get their lobe book to see what is avail.Tom
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 02 Nov 2017 :  09:55:06 AM  Show Profile  Reply with Quote
First, why do you want to limit your valve lift to 0.450" lift ?

If you want to mimic the XE268H cam call Bullet Racing Cams and talk with Tim. Consider a custom cam using their lobe number H270/300

270
224
0.3000" libe lift x 1.5 = 0.450" lift

Use a exhaust lobe suitable to work with your cylinder head intake-to-exhaust flow ratio. In addition it can be ground with any lobe separation desired.

http://www.bulletcams.com/Masters/Hlobes.htm

If you want to work with Comp Cams their Magnum lobe number 5202 is similar to the Bullet lobe above.

.

Edited by - Steve C. on 02 Nov 2017 10:00:31 AM
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Blued and Painted
Chief PONTIAC

USA
3505 Posts

Posted - 02 Nov 2017 :  10:36:40 AM  Show Profile  Reply with Quote
Comp cams has a great web sight and builds fast race cars but
There have been so many threads about valve train noise and spark knock associated with the flat tappet XE lobes.

The shorter stroke 400 is capable of some rpm's where the XE cams build allot of bottom end power.
Generally speaking, increase duration helps rpm's where more lift increases power.
.500 lift is 1/10 of an inch more than factory.
IMO It would be worthwhile to have the heads set op for .500 or more lift.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 02 Nov 2017 :  11:35:45 AM  Show Profile  Reply with Quote
"IMO It would be worthwhile to have the heads set op for .500 or more lift."

Good comment. And that works with what I've posted on many related conversations.....

"If you want to build a street motor with the most power without a sacrifice of idle and low speed qualities, then lift is the most important factor to maximize, not duration. The best street cams are those that seek to maximize valve lift while only adding a minimal amount of duration."

David Vizzard


.
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phil400
Crazy Horse

Canada
504 Posts

Posted - 02 Nov 2017 :  11:53:24 AM  Show Profile  Reply with Quote
Ok thanks for the info.

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive.
77 T/A sold
85 Monte Carlo SS sold
83 Mustang GT sold
"Let me tell you what Melba toast is packing"
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 02 Nov 2017 :  6:46:43 PM  Show Profile  Reply with Quote
Upgrade valvesprings to increase the maximum spring travel.

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Matt H
Cochise

USA
339 Posts

Posted - 21 Jan 2018 :  11:40:23 AM  Show Profile  Visit Matt H's Homepage  Reply with Quote
Phil 400- I know this is a older post but I don't think you will pick up much more hp going with the xe268 over the old 268H. I ran that same cam 268H in my 400 4spd years ago. I tried several other cams over the t years. I tried the XE 256 and the famous 744 cam. I ran the 268H for 10 years. It ran a best of 14.4 @ 97 mph. Car was a WS6 1979 400 4-spd PWH 400 with the 6x4 heads, stock Qjet , performer intake, 268h compact. Hooker 4109 headers. Factory 4spd, 3.23 gears.

The 268H compcam ran better than the 744 by far,. It was 7 tenths faster. In the 1/4 mile. Never ran the xe256 at the strip. It felt real strong bottom end and midrange. i don't think the 268H gave anything up to the XE 256. The 268H was strong on the bottom end and real strong midrange . If I had it all over to do again I would have stayed with the 268H cam. It was a waste of time and money swapping out the cams. With my set up it was also a waste of time to go from 3.23 gears to 3.73 gears. I ended up going back to the factory 3.23 gears.

Unless your doing some head work I would stay with the 268H cam over the XE268. Not worth the trouble or cost to swap them out. Just my Opinion.
If you picked up 10-15 hp you would not even notice that in the seat of the pants dyno.

Current car-1981 TA Pace Car. 461 stroker
1979 TA 400 4spd -sold

Matt
1981 Pontiac TA Pace Car
461 with 6x8 stock iron heads. 3.08 gears

Edited by - Matt H on 21 Jan 2018 11:46:06 AM
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Matt H
Cochise

USA
339 Posts

Posted - 21 Jan 2018 :  11:50:21 AM  Show Profile  Visit Matt H's Homepage  Reply with Quote
quote:
Originally posted by Matt H

Phil 400- I know this is a older post but I don't think you will pick up much more hp going with the xe268 over the old 268H. I ran that same cam 268H in my 400 4spd years ago. I tried several other cams over the t years. I tried the XE 256 and the famous 744 cam, also the Crower 60916 cam. I ran the 268H for 10 years. It ran a best of 14.4 @ 97 mph. Car was a WS6 1979 400 4-spd PWH 400 with the 6x4 heads, stock Qjet , performer intake, 268h compact. Hooker 4109 headers. Factory 4spd, 3.23 gears.

The 268H compcam ran better than the 744 by far,. It was 7 tenths faster. In the 1/4 mile. Never ran the xe256 at the strip. It felt real strong bottom end and midrange. i don't think the 268H gave anything up to the XE 256. The 268H was strong on the bottom end and real strong midrange . If I had it all over to do again I would have stayed with the 268H cam. It was a waste of time and money swapping out the cams. With my set up it was also a waste of time to go from 3.23 gears to 3.73 gears. I ended up going back to the factory 3.23 gears.

Unless your doing some head work I would stay with the 268H cam over the XE268. Not worth the trouble or cost to swap them out. Just my Opinion.
If you picked up 10-15 hp you would not even notice that in the seat of the pants dyno.

Current car-1981 TA Pace Car. 461 stroker
1979 TA 400 4spd -sold



Matt
1981 Pontiac TA Pace Car
461 with 6x8 stock iron heads. 3.08 gears
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Lee
Sitting Bull

171 Posts

Posted - 22 Jan 2018 :  12:46:09 PM  Show Profile  Visit Lee's Homepage  Reply with Quote
Phil, have you seen my thread on the low-lift cam I installed in my 455?

IMHO, not much to gain with higher lift on unported stock D-ports. But a MUCH greater chance of premature (or near instant) cam failure with aggressive high-lift HFT's.

CURRENT: '73 T/A clone, starting to get less boring!...
67 Firebird (sold) 11.27 @ 119.6 Feb. '05 issue HPP
69 Falcon wagon, 10.51 @ 130mph Feb. '10 issue PHR (sold)
72 Cutlass Convertible, first car, owned since '82, now with a 6.0 LS, mild, putting just under 400 hp/tq to the wheels.
www.LNLPD.com
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phil400
Crazy Horse

Canada
504 Posts

Posted - 23 Jan 2018 :  07:25:16 AM  Show Profile  Reply with Quote
Matt, I agree the 268H pulls real hard down low and thru he mid range, but is all done around 4300rpm I'm planning another short block to safely tuck my my match # block aside and simply just transfer my 6x-4 heads over the new shortblock, the heads were gone thru some years ago so I know they can handle .450 lift. I'm on a tight budge poniac parts are not plentiful nor cheap around here. looking at all my options.

Lee, yes I have and I totally agree with you, probalem is all the all the shelf cams have more lift built in.

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive.
77 T/A sold
85 Monte Carlo SS sold
83 Mustang GT sold
"Let me tell you what Melba toast is packing"
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 23 Jan 2018 :  07:56:20 AM  Show Profile  Reply with Quote
I'm sure Bullet Racing cams could do a custom with the lobe lift that will suit your needs. Ask for Tim.

http://bulletcams.com/Masters/Hlobes.htm


.

Edited by - Steve C. on 23 Jan 2018 07:57:19 AM
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 23 Jan 2018 :  09:20:37 AM  Show Profile  Reply with Quote
Curious...

Are you limiting your valve lift because of the valve springs currently in use ? And shouldn't the heads in use flow up thru .500" lift ?

.
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Lee
Sitting Bull

171 Posts

Posted - 23 Jan 2018 :  10:18:03 AM  Show Profile  Visit Lee's Homepage  Reply with Quote
Phil, correct, you won't likely find a decent mild/low-lift Pontiac cam available off the shelf. I get better pricing on Comp Cams, but Bullet just had a MUCH better choice of lobes in the durations I was looking for, so I had them custom grind the cam I'm using.

I'm honestly surprised at how well this cam is working for me! I expected it to make 250, MAYBE 260hp at the wheels. Hitting 270 with the crappy exhaust system was a shock to me! I hope to dyno tomorrow, to test the new 3" exhaust system - I am afraid to even make a prediction!

BTW, my heads were set up for a Comp 268H. The 268 and the lifters were in great shape, so I knew I'd be safe if I kept the lift under .450".

CURRENT: '73 T/A clone, starting to get less boring!...
67 Firebird (sold) 11.27 @ 119.6 Feb. '05 issue HPP
69 Falcon wagon, 10.51 @ 130mph Feb. '10 issue PHR (sold)
72 Cutlass Convertible, first car, owned since '82, now with a 6.0 LS, mild, putting just under 400 hp/tq to the wheels.
www.LNLPD.com
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phil400
Crazy Horse

Canada
504 Posts

Posted - 23 Jan 2018 :  5:20:50 PM  Show Profile  Reply with Quote
Steve, the heads have already been gone thru And can handle .450 as is. I don?t want to spend all kinds of money getting longer valves or whatever in order in get .500. These are stock not ported, with 30 degree seats. Seems the gains going from 450 to 500 lift isn?t worth the the money, especially since this isn?t a race engine and wil driven many hard street miles,

I?ve read many times Pontiacs have excellent low lift flow, is this wrong?

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive.
77 T/A sold
85 Monte Carlo SS sold
83 Mustang GT sold
"Let me tell you what Melba toast is packing"
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 23 Jan 2018 :  6:58:47 PM  Show Profile  Reply with Quote
Thanks phil400, I was just curious.

There is a popular Crower spring that will allow additional valve lift installed at 1.600" for $127 at Summit. No other changes. This if your springs have lost pressure with use. Also I've noted of late Paul Carter's comments about 30 degree seats needing additional spring pressure.

Just conversation.


.
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phil400
Crazy Horse

Canada
504 Posts

Posted - 23 Jan 2018 :  7:34:32 PM  Show Profile  Reply with Quote
Steve no offense taken. I've read alot of your posts on this site and PY, you know your stuff. All apreciated.

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive.
77 T/A sold
85 Monte Carlo SS sold
83 Mustang GT sold
"Let me tell you what Melba toast is packing"
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 23 Jan 2018 :  7:39:36 PM  Show Profile  Reply with Quote
I just Google up stuff that I think will be of interest !

Harvey Crane used tappet duration rated at .004" lift. Depending who you talk to at Crower they rate their hyd flat tappet cams at .005" or .006". It will make a difference, so it's not technically correct.

.

Edited by - Steve C. on 23 Jan 2018 7:42:50 PM
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phil400
Crazy Horse

Canada
504 Posts

Posted - 24 Jan 2018 :  07:14:51 AM  Show Profile  Reply with Quote
With the crower 68404s and the stock keepers and o-ring valve guide seals how much lift could one theoretically run?

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive.
77 T/A sold
85 Monte Carlo SS sold
83 Mustang GT sold
"Let me tell you what Melba toast is packing"
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 24 Jan 2018 :  10:03:40 AM  Show Profile  Reply with Quote
It will depend on the actual installed height, and that should be verified, do not guess. But assumed at it's rated 1.600".

As I understand it.... 1.600" -minus 0.950'coil bind- minus 0.060" safety margin if used = 0.590" lift in theory. That said, I don't know about other pertinent factors involved like the Valve Spring Retainer to Valve Seal Clearance, etc.

How Much Valvespring Coil-Bind Clearance Is Safe?

http://www.hotrod.com/articles/how-much-valvespring-coil-bind-clearance-is-safe/

However IF you are considering a custom cam with increased 0.200" duration and higher lobe lift I would get the spring pressure recommendation from the cam grinder after he is told about all the specs for the cylinder heads in use, like valve weight and the intended application, is it street only or often banged on at the race track which might require a bit more pressure. Also the intended RPM involved, etc.

.

.

Edited by - Steve C. on 24 Jan 2018 10:08:24 AM
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phil400
Crazy Horse

Canada
504 Posts

Posted - 24 Jan 2018 :  12:30:36 PM  Show Profile  Reply with Quote
Ok, I'm not planning to run anywhere near that much lift so good know, thanks.

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive.
77 T/A sold
85 Monte Carlo SS sold
83 Mustang GT sold
"Let me tell you what Melba toast is packing"
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