I know everyone has an opinion on what the cc these heads came from the factory stock, but I had mine milled and was wondering how much 15 thousanths took off?



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1992 Texas DPS B4C 1LE FE2 5.0/5spd:
TPIS Tricks
Intake and Plenum Ported
Fully Ported Corvette Heads
NOS FI Fuel Pump
K&N's Adj. Fuel Pressure Regulator
Alston SFC's
Energy Supension Hyperflex system
MSD 6AL
SLP 1 3/4" SS Headers
3.73's with 275/55/16's out back...blew those now 2.73 one legger
My complete back seat
encompases my RF tunes...

Currie 9" on the way with 3.70 gears

Adam

 

15 thousandth's. J/K. Well if you have a verneir or an inside micrometer you could find the diameter of the inside of the chamber and then do a volume calculation with .015 to find cubic inches and then convert to cc. I am not sure what the conversion to centimeteres is.

James

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If the women don't find you handsome they should at least find you handy. Red Green

 

92,
How much did 15 thousanths take off ?

Oh, about .015 inches.

Hey man, you asked - so..........

But really, here's the gig. I do not have exact specs for that head, but I can provide a reasonable facsimile. On the old cast-iron 66cc Chevy small block head (high performance), which has the same combustion chamber design (quench) it is:

.15cc's of volume for every .001 milled. So, if you milled the 15 thousanths, you decreased chamber volume by 2.25 cc's.

For a real-world impact scenario using this effect on a 350 Chevy with 9.5 to 1 compression (measured), it would increase it to 9.7 to 1.

This equates to a 1% horsepower increase.

And oh, 1 cubic inch = 16.387 cc's.


BOR

 

Thanks Box! You saved me having to get out math books! I'm fixen to build a 350 and want to have decent compression, but not too much, just in case if I want to add a SC! I want to take the guess work out of the scenario and I plan on cc'ing the heads and measuring exactly what the compression ratio is! Again thanks for your time.

Adam

 

If its the aluminum vette heads, they are 58cc stock. I dont think there is any disagreement about that one either.

The cc to milling amount listed still applies the same.

 

max,


so what about the people who say they have vette heads that range from 53 to 64 cc....

never atually measured mine thats all....
let me know if you have any real proof about these heads....and the same as far as milling does...

I'm not trying to be an *** just want some solid #'s



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1992 Texas DPS B4C 1LE FE2 5.0/5spd:
TPIS Tricks
Intake and Plenum Ported
Fully Ported Corvette Heads
NOS FI Fuel Pump
K&N's Adj. Fuel Pressure Regulator
Alston SFC's
Energy Supension Hyperflex system
MSD 6AL
SLP 1 3/4" SS Headers
3.73's with 275/55/16's out back...blew those now 2.73 one legger
My complete back seat
encompases my RF tunes...

Currie 9" on the way with 3.70 gears

Adam

 

I can tell you that my vette heads, after deshrouding the valves and polishing the entire chamber, still only measured 53cc.
Roy

 

Roy, one of three things (or combination) ... either you measured wrong, the heads have been milled or your heads are not the true L98 aluminums. The majority of 4.00" bore based engines (302, 327 and 350) got 64cc (performance) and some got the 76cc (emissions). Only the 305 and the aluminum L98 corvette heads (not the B2L cast irons found in F-bodies) were 58cc.

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George P. Lara
1994 Z28 LT1 T56
1984 Z28 High Output
Member: SCCA, SCFB, SC3GFB

 

Interesting, I never heard of a discrepancy with the cc on those heads. The ones I had varied slightly as production castings usually do, but they were all around 57-60cc. I did some other work to the chambers and milled them and ended up with a final cc of 61.

 

Nope, didnt measure wrong, And the heads were bought over the counter from GM in 88. We double checked the measurement because I was expecting somewhere in the low 60s for cc. I did install new manley undercut valves in both the intake and exhaust and it may have been that they sat a little higher in the chamber, and dont have the same concave shape of the stockers, but I didnt expect that large a discrepancy. I was actually happy for the small CC as it helped bring the dished pistons I was using up to where I really wanted it anyhow.
Roy
Roy