i am building a 355 engine for my firebird

its going to be bored .030 over

this will be the kit going into it

• http://www.summitracing.com/parts/FEM-MHP126-300/
• stock crank and stock rods
  this cam
• http://www.summitracing.com/parts/CCA-CL12-254-3/
  and this intake
• http://www.summitracing.com/parts/EDL-7101/

noisey gear drive

with either 624 heads or 882 heads both will be redone and matched at 2.02 intake and 1.60 exhaust with these springs http://www.summitracing.com/parts/CCA-986-16/

it will be topped off with a 750 holley double pumper

what do you all think this will roughly put down hp and tq wise for both options the 882s or the 624s and what would my approximate compression ratio be?

 

882 and 624 were the heads responsible for the legendary 160 HP 2-bbl and 180 HP 4-bbl motors of the 70s.

Expect to get numbers somewhere around in there.

IOW, expect to lose every race you ever participate in, even against 305s and 6-cyls.

Not sure why you think it's a good idea to concentrate on that other trivia and ignore THE ONE THING most limiting the potential of your project by choosing THE ABSOLUTE WORST POSSIBLE option for heads, with maybe the exception of TBI heads.

 

i just found a set of 461 heads that i will be going with.

so what are the approximations now doc

 

If you have one of these cars (3rd gen F bodies), won't fit your car

 

odd. i know someone who built an 84 camaro with double hump heads on a chevy 400. i guess i gotta go with a set of aftermarket heads or scrap the body and buy something it will fit in since the PRICE OF HEADS IS SO F(&*^*%^&CKINg high...

er i mean i suppose i shall look for a set of l98 heads

 

Yup; the double-humps WITH BOLT HOLES will fit the car. (Any of em will fit THE MOTOR) 461 however is the old early 60s design that lacks the provision required for minor details like... an alternator .... in these cars. or for that matter, most any car built since about 69. And of course the old stuff lacks the hardened seats as well, meaning they tend to live VERY short lives when fed modern fuel.

Yeah L98 heads would be a FAR better way to go.

 

Those are the flow numbers for 882 heads. They fall on their face after .400 lift. With a good 3 angle job, hogged and blended, 2.02 and 1.60 SS valves. They will transfer the curve a bit more forward. So you can take advantage of up to roughly .500 lift and they wont hit a brick wall at .400 lift. I also use a high rise manifold to offset the brick wall effect that the heads might have left over.
75/58 @ .100
125/108 @ .200
175/135 @ .300
204/141 @ .400
205/142 @ .500
206/142 @ .600

I got the head work done on my 882 heads for a seriously cheap price, I matched a cam as well .480 280/270. The biggest issue is finding the compression you need stock pistons wont due. Im Using KB forged with eagle rods, I cant remember the specs off hand. I also had a clean up deck done on the heads. I am right around 9.58:1 CR.

Everything is done to push the power curve towards the top end. I haven't had the car dyno'd yet but I can tell you that I am 99% confident that its producing just under 400hp.

 

Cam is abit too big for a 355 with that intake and those heads. The heads being weak will require more cam to make power but I think is a bad match. Why not find some junkyard vortec heads?

 

Agreed, unnecessary cam for the head and intake combo. Intake stops making good power before the cam runs out of steam. The power curve of that cam is more heavily weighted towards the top end. You need something that will benifit you mid range much better. .480 or less and 270 duration.. Keep the LSA 112 or more if you like street driving. I run a 108lsa and its a bit choppy for the street.

Not to mention if you run that cam with pressed in studs you will eventually wind up with your rocker studs pulling out and valve-train wrecked. Pressed in studs reach their limit around .480 yes some people run more but some people also had their studs pull out with less. you can make the decision.