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I am putting together a 350 chevy engine to go into my 1972 chevelle. I am looking to get 330+ horsepower. The engine is a 1976 4-bolt and the lower end is in great shape. The heads I am planning to use are stock 58cc (1.84 intake, 1.50 exhaust). I was going to go with an edelbrock performer manifold, a 650cfm carb and a beefed up cam (say a 270). Am I on the right track ?
 

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jjpodlas said:
I am putting together a 350 chevy engine to go into my 1972 chevelle. I am looking to get 330+ horsepower. The engine is a 1976 4-bolt and the lower end is in great shape. The heads I am planning to use are stock 58cc (1.84 intake, 1.50 exhaust). I was going to go with an edelbrock performer manifold, a 650cfm carb and a beefed up cam (say a 270). Am I on the right track ?

Ya, I'd suggest you look to CompCams Extreme Energy series flat tappet hydraulic XE256H.....212-218 duration with 447/454 lift on 110 centers.....or even one step smaller XE250H. Stock heads should support that and perform well with your combo.

Be sure to get cam, lifters, gears, springs as a set from Comp. :thumbup:
 

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My family (uncles and stuff) personally like Schneider cams; founder of the company used to be partners with Crower, but they split around 1960. Besides, everyone and their grandmother runs comp cams, msd ignition, and flowmasters. Be different from everyone else. :thumbup:

www.schneidercams.com
 

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xntrik said:
Ya, I'd suggest you look to CompCams Extreme Energy series flat tappet hydraulic XE256H.....212-218 duration with 447/454 lift on 110 centers.....or even one step smaller XE250H. Stock heads should support that and perform well with your combo.

Be sure to get cam, lifters, gears, springs as a set from Comp. :thumbup:
xntrik, I'm not sayin' you're wrong, but it appears that he is using 305 heads on a 350. I don't know what the original compression ratio was, but in '76, I'm guessing somewhere around 8.5 due to the crummy gas in those days. I'm also guessing the '76 heads would be 75 or 76 cc's. A change to 58 cc heads could put him over 10:1 and cause detonation problems with a short cam. Help me out here please.
 

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techinspector1 said:
xntrik, I'm not sayin' you're wrong, but it appears that he is using 305 heads on a 350. I don't know what the original compression ratio was, but in '76, I'm guessing somewhere around 8.5 due to the crummy gas in those days. I'm also guessing the '76 heads would be 75 or 76 cc's. A change to 58 cc heads could put him over 10:1 and cause detonation problems with a short cam. Help me out here please.

You're right. That could be true. But of course we don't know if he is using those dismal 8.0 dish top pistons.

Isn't it fun to try and spec something with little or no information? :thumbup: and sometimes the builder doesn't have a clue as to what to look for.
 

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A '76 350 would have right at a 12cc dish, even the L-82, assuming a .041" thick head gasket and .025" deck height he would be right at 9.5 to 1 with 58cc heads, with a mild cam that closes the Intake valve around 60* ABDC his DCR will be 7.88. I was originally going the same route with my '76 but one thing led to another and............ well, you know how that goes.

You can get those HP numbers with better heads and a milder cam and have better low end torque if you're willing to step up to a later model 350 so you can run a factory roller cam. A 9 to 1 350 with the Marine roller cam and stock vortec heads will put you right at 330 FWHP @ 5,000 RPM with a truck load of TQ from an idle through 4,000. It will idle like a sewing machine though, no lopey cam to impress the drive in crowd and it will only rev to about 5200 or so before it noses over but by then it's all over on the street anyway. Slip in a ZZ4 cam and the HP and RPM range goes up but bottom end TQ goes down, it still has more than enough though. Just something to consider, the Marine cam pops up on eBay fairly often for about $70 for a crate motor take out. I'm building that exact combo for my pickup, talked to a guy with one just like it and his put out 247 RWHP on a chassis dyno with a 700R4 and 3.73's, that translates back to just a hair over 350 flywheel HP. DD2000 gave me almost the exact same numbers for mine.
 

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"with a mild cam that closes the Intake valve around 60*"

A mild cam will close 27* to 33* ABDC @ 0.050" tappet lift, not 60*. If using the KB calculator and adding 15, you're still around 45*. I'm not arguing with you, I'm just trying to help the fellow by getting all the facts on the table.
 

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Hippie said:
A '76 350 would have right at a 12cc dish, even the L-82, assuming a .041" thick head gasket and .025" deck height he would be right at 9.5 to 1 with 58cc heads, with a mild cam that closes the Intake valve around 60* ABDC his DCR will be 7.88. I was originally going the same route with my '76 but one thing led to another and............ well, you know how that goes.QUOTE]

that also assumes the engine was never rebiult, of came from a nother vehicle.
 

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techinspector1 said:
"with a mild cam that closes the Intake valve around 60*"

A mild cam will close 27* to 33* ABDC @ 0.050" tappet lift, not 60*. If using the KB calculator and adding 15, you're still around 45*. I'm not arguing with you, I'm just trying to help the fellow by getting all the facts on the table.
I used Pat Kelley's calculator and seat to seat timing from some of the milder cams I have been plugging into it not the timing at .050" plus 15* the KB calculator uses but it's good you clarified that. Thanks. :thumbup:


techinspector1 said:
that also assumes the engine was never rebiult, of came from a nother vehicle.
Yes and we all know what happens when we assume. But until he tells us otherwise.......;)
 

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Discussion Starter #10
the engine has never been re-built. Do most agree that compression ratio will be ok with the 58cc heads ?
 

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I would never build an iron head motor over 9.0:1 without setting the squish (piston crown to head clearance @ TDC) to 0.035" to 0.040". In my opinion, you're asking for trouble, but hey, that's just my opinion.
 
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