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Old 05-31-2012, 07:52 PM
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need help choosing the right head specs

Hey guys i've got a 1979 350 small block chevy and i'm in the market for some new heads and need some suggestions

the engine has the standard bore, stock pistons(dished), stock heads, mild cam which is just slightly more agressive than stock, double roller timing chain, performer eps intake, 600cfm edelbrock carb, block hugger headers, true dual exhaust with flowmaster mufflers(no cats)


looking to get a pair of heads that will raise my compression out of the smog era numbers and to have good throttle response and mid range torque and to have around 300 hp nothing too crazy

so with all that said any heads that would be a perfect match ? best combustion chamber size, intake runner size ?

edit just some extra info - engine is mated to 5 speed manual transmission and 3.73 rear gears

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Last edited by xzero117; 05-31-2012 at 08:13 PM.
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Old 05-31-2012, 08:30 PM
How fast is fast enough?
 
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195cc or smaller runners, 1.94" intake valve, 64cc chamber, preferably iron.
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Old 05-31-2012, 08:35 PM
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Quote:
Originally Posted by ap72
195cc or smaller runners, 1.94" intake valve, 64cc chamber, preferably iron.
why iron ? seems like nowadays all the aftermarket brand heads come in aluminum and iron versions are rarer and not in stock as frequently as their aluminum counterparts
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Old 06-01-2012, 07:18 AM
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There is the erroneous perception that aluminum heads make "more" power. In fact, all things beng "equal" (flow, compressoin ratio, etc.) IRON heads make more power by NOT "soaking" as much heat out of the combustion process as aluminum, helping maintain the efficiency of the "burn". I often read "you can get away with more compressoin with aluminum without detonation". Somewhat true. "Get away with" is the error. You MUST run higher compression with aluminum to achieve the same power level. A prominent magazine did a test using Iron Eagles and Pro-1s, ported by the same man to the same specs. Chamber volume was equalized. The Iron Eagles made about 3-4% more across the range. After milling .030" off the Pro-1s to increase compression about 1/2 "point", they (aluminum) equalled the output of the iron.

From a machine shop's POV, aluminum is easy to "deal" with. That is, you get more for your "porting dollar" with aluminum. Aluminum is easier to repair in the case of a catestrophic failure. Aluminum is lighter (significantly). Add all this "up" and you can understand why aluminum is more popular. "Popular" and "better" aren't always synonimous...

FWIW

Jim
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Old 06-01-2012, 07:55 AM
How fast is fast enough?
 
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Quote:
Originally Posted by Mr. P-Body
There is the erroneous perception that aluminum heads make "more" power. In fact, all things beng "equal" (flow, compressoin ratio, etc.) IRON heads make more power by NOT "soaking" as much heat out of the combustion process as aluminum, helping maintain the efficiency of the "burn". I often read "you can get away with more compressoin with aluminum without detonation". Somewhat true. "Get away with" is the error. You MUST run higher compression with aluminum to achieve the same power level. A prominent magazine did a test using Iron Eagles and Pro-1s, ported by the same man to the same specs. Chamber volume was equalized. The Iron Eagles made about 3-4% more across the range. After milling .030" off the Pro-1s to increase compression about 1/2 "point", they (aluminum) equalled the output of the iron.

From a machine shop's POV, aluminum is easy to "deal" with. That is, you get more for your "porting dollar" with aluminum. Aluminum is easier to repair in the case of a catestrophic failure. Aluminum is lighter (significantly). Add all this "up" and you can understand why aluminum is more popular. "Popular" and "better" aren't always synonimous...

FWIW

Jim
That and with your dished pistons you'll be low on compression, going iron will slightly help that but its not a huge difference.
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Old 06-01-2012, 11:14 AM
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There was a very good recent thread about the Edelbrock E street heads.
Replaced stock 441's. Poster really really likes the performance gain.
(1 full set ET) Thats good bit.
The price is right and they are made in America.
I would install with a thin felpro 1094 gasket
to max the compression gain with dished pistons.
A head bolt retorque is a must, but easily done
after a few heat cycles.

I would consider changing the dished pistons for flat tops
while you got it apart. ...or
I might consider milling a bit (.030 .040) off the heads
to make th chambers smaller (58cc)
Once you get the heads you can also step up the cam
to real good effect now.
I suggest a Isky 270H Mega Cam #201271
or Crane Energizer 278 H-10 #10013
Both really good moderate street friendly performance cams for a car like yours.

Your intake is fine. If you get a chance try a 750cfm carb
99% of the time they perform better and make more power.

stock dished pistons 64cc heads .015" gasket 9.2:1

"" "" 58cc heads .015 gasket 9.8:1 (thats where you want to be)

Now you got a motor for the New Millennium

Last edited by F-BIRD'88; 06-01-2012 at 11:33 AM.
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Old 06-01-2012, 11:15 AM
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With the mild combo you got all you need is a set of Vortec heads and a Vortec intake. A set of RHS Vortec heads will fill the bill perfectly for your combo. You'll be amazed at how much power it'll pick up. Use the GM head gasket with .028 thickness couped with the 67cc chambers of the RHS heads will put your compression ratio right around the 9:1 mark which is ideal for your combo and it'll run fine on 87 octane pump gas.
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