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 76 formula 400cid
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 07 Dec 2017 :  09:26:54 AM  Show Profile  Reply with Quote
Hi I?m new to this group I was wondering if anyone could help me out here I bought this car and I went threw the engine I went 30 over and Installed the edelbrock performance rpm intake and cam and performance rpm carb 750cfm and also put new valve springs and retainers timing gear set all on the original heads how much hp and performance should I be getting out of this set up and also should I go with better cast iron heads or aluminum ones

Robert

Bill Boyle
Horse Feathers (Charter Member)

USA
4834 Posts

Posted - 07 Dec 2017 :  09:50:01 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Robert, welcome to PSP forum.

The Edelbrock Performer RPM cam you indicate was installed with your low compression iron heads is not a good selection of parts. Considerably more static compression is needed to benefit from that 231/240 intake duration cam and valve lift of .470" with 1.5 rockers.

Your engine is not producing strong low or mid range torque with the original low compression iron heads of 1976. That cam and RPM dual plane intake requires at least 9.5 static compression if not higher. But, the higher the CR the more difficult it is to tune the engine so it doesn't ping. Edlebrock aluminum heads would probably be your best bet to drastically improve power. In fact, Edelbrock claims that such a combination would produce 422 hp using 60599 aluminum heads.

As far as hp presently, my guesstimate would be 275-300 net hp because of mismatched cam and heads.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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tjs44
Cochise

USA
422 Posts

Posted - 07 Dec 2017 :  12:59:38 PM  Show Profile  Reply with Quote
The carb was also not a great choice,the factory QJ is much better.The intake is also not as good as the factory.Tom
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 07 Dec 2017 :  2:08:51 PM  Show Profile  Reply with Quote
Bill what would be the best thing to do next and what rearend should I put and still drive it a a daily diver

Robert
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Steve C.
Crazy Horse

1691 Posts

Posted - 07 Dec 2017 :  2:22:37 PM  Show Profile  Reply with Quote
Before you consider tearing things apart call Tim at Bullet Racing Cams about a custom hydraulic flat tappet cam to build some cylinder pressure. Tell him everything about you current compression and parts in use. Ask him about his lobe number H264/310 (216 @.050) on the intake side. He will suggest the proper exhaust lobe. Then have it ground with a 108 lobe separation.


.
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Bill Boyle
Horse Feathers (Charter Member)

USA
4834 Posts

Posted - 08 Dec 2017 :  06:37:26 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Robert you sent me an email and told me your Formula is running a 2.73 rear gear. With the low compression heads on the 400 plus the Edlebrock's version of the 041 camshaft, the car is not performing and accelerating well, IMO. My guess is that your engine is sporting large valve 6x-8 heads, that provide a whooping 7.6 to 1 static compression ratio. Not good for performance even with an aftermarket cam that builds cylinder pressure.

Robert--depending on how you want to use the car, there are options available to get the right combination of parts together.

If you want to stay with the big 041 styled cam, you need to do one of two things regarding heads. Either buy a pair of Edelbrock heads, either D-port exhaust style or round-port exhaust style (A careful look at chamber size and exhaust ports are important on both styles.) or find a set of high compression OEM iron heads and have them fully machined including a modification to the chamber size as well as porting. The cost of working up old iron heads may cost as much as out- of- the box Pontiac 400 E heads. Your budget is alway a factor and must be balanced with performance needs.

Other performance factors come into play such as the piston rods and pistons. How many miles on this engine? Robert, does your engine still have stock OEM piston rods and pistons still in the 400? Has it been bored out? These are things pertinent to building a strong dependable high performance engine. The low cost of good aftermarket piston rods and forged pistons today pretty much eliminates the need to rework old rods to reuse and put new forged piston on them.

What about the bottom end? If the piston rods and pistons are still stock how many miles on this 400 engine? What is the condition of the rod and crank bearings? I wouldn't spend thousands of dollars on heads, camshaft, intake, carb, springs, valves, gaskets etc and mount them on a worn bottom end to find out 1000 mile later that the engine spun a bearing. Maybe that crank needs new bearings or needs to be turned. Something very practical to consider.

One thing is certain, that 2.73 rear gear is an anchor chain holding back acceleration. It needs to go and be replaced with 3.23 gears or lower (3.42, 3.55, 3.73 for instance, depending on usage). The rear end must have a working posi unit.

The 041 Edelbrock styled camshaft likes low gearing. (3.73 or 3.90) Those gears are not for lengthy highway driving, as the engine rpm will be high at highway speeds. A high gear like 3.23 is decent for highway and street--a compromise--but is best suited for a smaller camshaft with less duration.

[Robert in my vintage 57 Chevy Wagon, it used a 4.56 gear but the car was a drag strip car only. Running 3.90 gears in your Formula will work with that 041 camshaft, E-heads, new rods, pistons, bearings, etc., but it will not be too street friendly.]

Tell us more Robert.


"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 09 Dec 2017 :  10:17:10 PM  Show Profile  Reply with Quote
When I put in the can intake carb I did the the whole bottom end polished the crank new bearings new rods and pistons .30 over the guy told me going . I p over would put my compression at 9:5:1 I want to use the car as street and cruse I?m it and have the power to take off and light up the tires while taking off

Robert
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 09 Dec 2017 :  10:17:45 PM  Show Profile  Reply with Quote
The heads and bottom don?t even have 2000 miles

Robert
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Bill Boyle
Horse Feathers (Charter Member)

USA
4834 Posts

Posted - 10 Dec 2017 :  05:58:31 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Robert--
Since your engine was "rebuilt" a short while ago, it's just a matter of what you want to do with heads. Get a set of D-port E heads, fully prepped ready to go and install them. There's a choice of 72 cc or 87 cc heads. Aluminum heads can handle more static compression than iron heads without causing detonation, so you may want to go with the smaller chamber. Your current exhaust, whatever it is, will bolt up to the D-port heads because they bolted up to the low compression heads you have on the engine. If you have full length headers that will be optimum. If you don't, you should. You will need a good exhaust system with E-heads.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 10 Dec 2017 :  10:04:47 AM  Show Profile  Reply with Quote
Nice info and yes I do have long tube headers hooker series 3 to three inch pipe and flow masters on the rear end can I swap out the gears on the existing one or get a a whole different one

Robert
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Bill Boyle
Horse Feathers (Charter Member)

USA
4834 Posts

Posted - 10 Dec 2017 :  1:06:23 PM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Robert--The best answer I can provide is to have a differential shop inspect your rear end and let them advise you on what needs to be done to upgrade the ring and pinion gearing, to something like 3.23, 3.42, or 3.55 (if available). Get a written estimate on total cost (parts, labor and tax) to do the job.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 10 Dec 2017 :  3:22:50 PM  Show Profile  Reply with Quote
If you have time can u text me at+13237124229

Robert
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Brian R
Crazy Horse

USA
1675 Posts

Posted - 11 Dec 2017 :  10:20:39 AM  Show Profile  Reply with Quote
Considerations before choosing the cam:

* Heads - flow, final compression
* Rear-end
* Curb-weight
* Transmission gearing
* Intake
* Use - race/street performance/highway

Robert - everything said prior to this post is dead on.

Mainly just wanted to warn you on rear-end ratio. I have 3.55's and wish every summer that I went 3.23's because I do a lot of highway driving. A stout Pontiac will have plenty of tourque to spin the rear's with 3.23's and be a bit more highway friendly.

Your car: Stock tranny? If so, probably a TH40. Great tranny but only 3 gears. If you plan on leaving it alone, this is a factor in rear-end choice too. If going with an over-drive tranny instead and your use includes highway, the 3.55's or 3.73's will be great.
If you never plan on highway use, these are not factors.

Bottom line is consider all when choosing a cam as then and only then can you match all for optimum performace.

Good luck
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 11 Dec 2017 :  12:20:33 PM  Show Profile  Reply with Quote
After hauling my bird home after years of storage I open the hood and I saw the stamping on the heads which are 6s heads meaning they are 101cc heads and is it to much for the parts I have installed already is there any way we can make these heads to 72 cc

Robert
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cortcomp
Coyote

USA
5354 Posts

Posted - 11 Dec 2017 :  12:50:54 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Can't answer the first part but there's no way you're shaving 100cc heads down to 72cc.
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tjs44
Cochise

USA
422 Posts

Posted - 11 Dec 2017 :  6:04:03 PM  Show Profile  Reply with Quote
if its a 30 over 400 I get that you will need about 81-82 cc heads with zero deck and a 41 gasket to get you about 9.5.Tom
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 11 Dec 2017 :  8:48:50 PM  Show Profile  Reply with Quote
Is there any good iron heads that Pontiac made or is Edelbrock RPM heads

Robert
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tjs44
Cochise

USA
422 Posts

Posted - 12 Dec 2017 :  09:11:19 AM  Show Profile  Reply with Quote
What is the primary use and goals of your engine?Stickily street driving?Some strip some most street?Just strip?Everything is a compromise,too much cam and they are not as much fun to drive,too much CR and you have to mix race gas.It takes the total package to make all the parts work together.Not one thing can be done to your combo right now to make it all good.Tom
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 12 Dec 2017 :  12:00:19 PM  Show Profile  Reply with Quote
I?m looking to be able to drive it and **** around with it excuse my language if you get what I mean

Robert
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Brian R
Crazy Horse

USA
1675 Posts

Posted - 14 Dec 2017 :  08:56:45 AM  Show Profile  Reply with Quote
6x-4's are smaller chamber and a good candidate.

The 6x-8's you have are smoggers all the way
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Brian R
Crazy Horse

USA
1675 Posts

Posted - 14 Dec 2017 :  09:01:34 AM  Show Profile  Reply with Quote
The 6x-4's will need bigger valves. 2.11/1.77

The seats are already hardened - some miner polishing and porting will yeild a nice performance head. With a 400 punch .30 over, I believe you end up with a 406. Zero deck the block too.
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 14 Dec 2017 :  1:06:12 PM  Show Profile  Reply with Quote
So the 6x-4 heads are similar to the edelbrock heads

Robert
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Bill Boyle
Horse Feathers (Charter Member)

USA
4834 Posts

Posted - 14 Dec 2017 :  6:25:43 PM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Edelbrock aluminum heads have smaller chambers than any 6X-4 iron head. As BrianR stated, they come with 1.66" exhaust valves and one way to increase exhaust flow is to move to the larger 1.77" exhaust valve. However, in order for you to run that head you need to pull that Edelbrock cam and put in another one that builds cylinder pressure. Running the low compression 6X-4 head even with port work will still not be close to ideal--you need a minimum of 9.5 static compression or better and you can't get there with the 6X-4 head. If It was possible I wouldn't have shelved them for a high compression iron head to work with on my 400.

If you looking for a high compression iron head, look at 62 heads and have them ported. That's what I did. You will be close to 10 to 1 static compression (unless the chambers are made larger) with those heads and they will provide plenty of pop for that big cam. Machine work will be expensive to set them up--an alternative--the aluminum D-port E heads. Either way, it's not cheap.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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Rcastellanos069
Tribal Scout

USA
11 Posts

Posted - 15 Dec 2017 :  8:08:34 PM  Show Profile  Reply with Quote
Nice info just don?t know where to go how much hp and tq does your set up on the 400 have

Robert
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Bill Boyle
Horse Feathers (Charter Member)

USA
4834 Posts

Posted - 16 Dec 2017 :  07:49:07 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Robert asked: "how much hp and tq does your set up on the 400 have"

No official dyno numbers on either torque or hp.

Upgrades made the last go round: 62 ported heads, chamber work, Scorpion 1.65 roller rockers, Comps 276AH cam, lifters, 2.5" exhaust, ignition timing, upgrades to carb were all done to reach or exceed 1 HP per cubic inch of displacement. I'm pretty certain the engine is there. I'm no longer racing at the strip or auto crossing the car. The car will eventually be exhibited at car shows.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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