STLCRZY

Guys , what you think- how much compr. we have with a 350 with 8 heads and flat tops and 040 head gasket?

Heads and block would be milled to be clean....give me an idea.. 9:2:1 or maybe more ???

cutlassefi

Bore X bore X stroke X 12.87 will give you cylinder cc's. The rest you can do from there.

olds 307 and 403

Use this.
https://www.uempistons.com/index.php...ge=calculators
With the old Speed Pro's and no milling, it will be just under 9 to 1 compression. Get the machine shop to use a bowl hog on the exhaust side, there is a lip right under the valve. already has 1.625" exhaust valve. Use a 2" or 2.07" on the intake with the same treatment.

STLCRZY

https://www.uempistons.com/index.php...ge=calculators
okay i´m a little unsafe with the numbers , so maybe someone can help.

Cylinder Head Volume (cc)
8 HEADS (stock not milled) = 79cc ??

Piston Head Volume (cc)= 0

Gasket Thickness= 0,040

Gasket Bore= ??
(about .060 larger than the cylinder bore diameter,is this correct?)

355 0,30 over-Bore Diameter= 4,087

Deck Clearance not milled= ??

Stroke = 3,385
====
Rod Length = ??

olds 307 and 403

Piston to deck is usually .025" with Speedpro Forged pistons and Felpro's gasket bore 4.230" and 79cc is the spec, I have measured 77-78cc but 79 should work. Use decimal points, not comma's. If you want more compression with just clean up milling, Rocket Racing offers a .028" thick head gasket. With a .006" clean up on the heads, you will lose one CC in combustion chamber size. You or your machinist will need to measure everything to be accurate but 9 to 1 should be close to what you end up with.

STLCRZY

So with 0,006" mill on the heads and the 0,040 head gasket i would have nearly 9,9:1...??....too much!!

STLCRZY

really don´t want to mill the intake to fit.

correct me if i´m wrong - with a 0,003" mill on the heads and nearly 73 -74cc i have a roughly 9,4:1 compression ???

Fun71

I have no idea where you got 9.9:1 as I get 8.78:1 using the numbers olds 307 and 403 posted.

olds 307 and 403

You figured that with 70cc which is a big cut, you must mean a .060" cut. I would get early heads if you want that high of compression. A .006" cut= 1CC of chamber volume. So if your heads are currently 79cc, that .006" cut will reduce them to 78cc. The cut would be .030" to reduce to around 73cc, depending where you are now.

STLCRZY

Yeep you are right

Any cam recommendation with nearly 9:4:1

Engine goes in chevy caprice (307 olds)
mild ported 73cc Heads with 2.07" Intake/ 1.625"
Performer Intake
Stock Conv.
No headers
Highway gears
Carb..not sure for now if stay with EDE ??

olds 307 and 403

You need a cam bigger than the 204/214 for sure. Talk to Cutlassefi, he just sent me out a custom cam for my 9 to 1 350. Mine is a 214/214 on a 110 LSA as an example. Tune the Edelbrock as they seem to be way off.

STLCRZY

are those valves the right one:

INT:
https://www.summitracing.com/int/par...1775/overview/

EX:
https://www.summitracing.com/int/par...ake/oldsmobile

or

https://www.summitracing.com/int/par...ake/oldsmobile

olds 307 and 403

Yah, those should work. Your heads already have 1.625" exhaust valves.

coppercutlass

I have a cam and lifters and cloyes timing chain. cam was used in one of my previous builds but good wear pattern , new lifters and cloyes timing chain . if you are intrested 125 bucks plus the ride. Its a howards 512/512 lift cam 227 /233 duration on a 110 lsa. I intalled them on the engine on the stand but i got a solid lifter cam and going with a billet cloyes chain as that engine will see much more sever use.

olds 307 and 403

Copper, that is a big cam for what he is doing, crappy highway gears, stock stall without headers in a heavy Caprice.

coppercutlass

Must have missed that part lol. Yeah too big for th e usage but this can you could run it with 9. 4 to 1 compression but not with that set up.