How can i identify if the engine has 9,5 or 10,25:1 compression by the engine code? The 4bbl has 10,25 and 2bbl 9,5:1 but if is has no intake or if its switched? heads are #5.

 

You can't without removing the heads and identifying the pistons.

 

I have tried read thru all litterature i could find in this subject but it only made me confused when no one could describe how determine comp ratio.
Thanks for guiding me in the subject!

I am searching for 68-69 standard high comp engines with 10,25 cr #5 heads.
Earlier i have bought an 69 engine with #5 heads but when it landed in my garage the cylinder one and three was rusted so badly it was stuck!
After 13! months the company sent me an 70 cutlass engine but it was an 2bbl so i belive that one being an 9,5 comp ratio (and another cam) and now he will send me one more engine but he want it to be right this time.
I see now that it can be a problem....
High compression at low cost was my goal, my intention was in running it on E85, 104 octane, and still keeping my EFI with some modification and using an lambdasond and and guage to that.
changing 180 hp to maybe 280 (net)would be nice.
the original motor suffered from drowning in fuel by foulty EFI and the bearings were worn down. I suspect it when hearing the noice on acceleration and that it was double amount of oil in pan and the oil smelled like and gas tank.