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Discussion Starter #1
I have a 1976 Pontiac 400 that has a fresh rebuild, 400 ho cam, Holley 650 on an Edelbrock Performer manifold, new headers and 2.5" exhaust w/ crossover. I currently have the stock 6X heads that were reconditioned, and fitted with roller rockers. The car is a 4 speed.

I was thinking that I was going to keep it pretty basic, and I still don't want to get to radical, but I need more power. Any ideas on what I can do?

I would guess I should go with a set of heads? If I do dip into the engine again, what kind of build would get me into the 350-400 hp range?

Thanks in advance for any suggestions.
 

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personally I would have went with a different cam, your carb sounds a little small (I don't have enough info on the car or engine tell you for sure), and the performer intake is more of a stock replacement intake (I have read of two real world tests where the performer actually lost hp over the stock cast iron intake). but if your engine is fresh, I'd leave it alone and start looking for power somewhere else, like your rear end.

btw, if your engine is a '76, your 6x heads are not stock. pontiac heads are very very good (especially 6x, 4x and 5c) and you are going to have to plunk down alot of cash to get slightly better heads. your money is better spent somewhere, almost anywhere, else.
 

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Grumpy Old Goat Herder
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I agree with wyomingoutlaw. The best bang for the buck, and most noticable gain, would come with a set of gears. I have run 4.56s on the street, but they're no fun on even a short trip. If you use the car for short trips, once in a while, I'd put 3.90s or 4.10s in it , but use a pretty tall tire.
 

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If you cruise the major hot rod magazines' sites you will find technical articles about 400 Pontiac builds and tests.

Junkyard Jewell, Pontiac 400 is an excellent article.

Your horsepower goals should be easy to reach and perfectly streetable with the proper cam and induction.
 

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Grumpy Old Goat Herder
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Without knowing your whole combo, it would be hard to give the best recommendations, but I understand (have never used one) that the Performer RPM works very good for a street/strip set up. Call your choice of cam manufacturer for a recommendation when you know how it will be set up (weight, gear, carb, etc), or one of the more popular Pontiac engine builders.
I can send you a couple of sites if you give me your email address or just email me, but be sure to put Pontiac in the subjec line, so that I can pick it out of my suspect email.

Bill
[email protected]
 

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Grumpy Old Goat Herder
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Summit part # EDL-7156; Performer RPM satin manifold. #71561; polished.
Page 12 in the latest catalog.
 

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WDCreech said:
Summit part # EDL-7156; Performer RPM satin manifold. #71561; polished.
Page 12 in the latest catalog.
Really I went Edelbrock site and that was all it showed for Pontiac.

I just went again, and clicking on change performance, RPM, it comes up not available........ duh?????? W>T>H>
 

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Grumpy Old Goat Herder
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It's been out for a couple of years, now. I haven't used either, but from what I've read on the Pontiac forums, the Performer won't do any better than a factory manifold. but the RPM will, especially in mid to upper rpms.
 

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i had an RPM intake on my 455 powered 69 custom s over 15 years ago. its been around awhile. now to your motor. a 400 pontiac should make 400 hp without breaking a sweat. i had stock 6x heads as well but on a 455. the comp 525 305 cam. but better cams are available now. holley 850. hooker super comps and 3 inch bullet mufflers. 2800 rpm ATI converter. 4:10 gears and 30 inch tires. car ran a best of 11.53 with 1.53 60' the car weighed just over 4000 lbs with me in it. your motor should make 400+ easy with the RPM intake, bigger carb, proper timing curve, the right cam, good headers, free flowing exhaust. and free breathing intake tract. i'd first make sure your timing is good for your combo. the carb is too small for sure. the rpm intake should be in your future plans. one other thing, what is your compression. what pistons did you use. and what was said before about the 400 poncho heads is correct. they are some of the best stock heads ever made in my opinion. the oldsmobile heads arent shabby either.
 

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Discussion Starter #13 (Edited)
I did have the distributor recurved after the build. The car dynod at 243.5 max hp and 300.9 max torque.

Its a 76 Trans AM, so I believe the wight with me in it would be around 4100.

I just found that I actually have a Holley 4160, 750 cfm, vac. sec. on it - maybe I could just change the jets out and be ok? I am definitely interested in going with the Performer RPM manifold, and looking into a better cam.

I am not sure of the compression or pistons right now....I have to look into it. I believe my headers and exhaust are good.

When I had the heads reconditioned, I didn't have any port work done. Is that something I should look into also?

I really appreciate all the help guys.
 

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stock 6x heads will support 400+ horse power. spend your money elswhere. 3:73 gears should be just right. i'd say intake, cam and cold air to the motor and 400hp should be yours. remember attention to details. bolting together parts doesnt a good running motor make. the parts need to work well together and must be tuned right. very important will be cam selection. i havn't run a pontiac in over a decade so i'm not familiar with whats new for pontiac motors. but i'm sure any reputable cam company will be glad to help you out. ive had my best experiences with crane and lunati. but any name brand cam co. will help you pick the right cam. since you have a gearbox cam selection will be different than for an automatic car. i know one thing for sure. once you do get that 400 poncho right, that'll be one blast of a car to drive. you'll be steering it with the loud pedal alot. as for the carb, i'm not a fan of vacuum secondary carbs but others make them work well. perhaps someone else can help you get that holley right. one more thing....i know this may sound stupid, but ive run into it before. i bought a 72 z-28 cheap because the guys newly built motor was a dog and he was disgusted with it. turns out the throttle cable was only opening the carb about 3/4 of the way. always check to make sure the blades are aLL THE WAY open when ya stomp it. i took the previous owner for a ride in the car just a couple hours after buying it, and adjusting the cable, he was sick.
 

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psmvchaser said:
I did have the distributor recurved after the build. The car dynod at 243.5 max hp and 300.9 max torque.

Its a 76 Trans AM, so I believe the wight with me in it would be around 4100.

I just found that I actually have a Holley 4160, 750 cfm, vac. sec. on it - maybe I could just change the jets out and be ok? I am definitely interested in going with the Performer RPM manifold, and looking into a better cam.

I am not sure of the compression or pistons right now....I have to look into it. I believe my headers and exhaust are good.

When I had the heads reconditioned, I didn't have any port work done. Is that something I should look into also?

I really appreciate all the help guys.

Was that engine power or chassis dyno power? That torque sounds awfully low to be engine power dyno.

Pulling 4100 pounds with a low compression engine is very cam limiting.

750 vacuum secondary is fine for your engine. Never a pure mechanical secondary.

Changing jets is only beneficial if your fuel mixture is incorrect.
 

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I have heard good recommendations for the Summit 2802 cam. This is the cam I am installing in my 1975 Pontiac 400 with 6x-4 (93 cc) heads.

bt
 
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