simonb.

hello from austria!

i am rebuilding a 350 from 1977.
it has the 3A heads. i dont want to make a race-maschine, just a solid cruiser
with (a little) more power than my old 307 had!

i will bring the block and the heads to a proffessional engine shop to do a 3 angle valve job and messure all the bores//bearing tolerances etc. and if necessary i will let it bore and get new pistons.

i have the fel pro gasket kit with the blue head gaskets.

how much should i mill the heads to get a better compression ratio?
i dont want/cant to buy better heads, because here in austria its impossible, getting the heads you want....

i have removed the air tubes and did a little porting., also i have the comp cams 260h kit with springs, timing chain etc. and an edelbrock performer.
200r4 and 3.08 posi rear.

the hole thing comes in my 76' buick skylark, so not a heavy car!


thanks for tips, simon!

olds 307 and 403

If he bores it oversize, get flat top or small dish forged pistons as replacements. Those heads suck on the exhaust side and are known to crack. If the heads are use able, mill them .020" if that motor is equipped with shim gaskets from the factory. I have heard conflicting info on the factory head gaskets on the 77 and later SBO.

simonb.

dont know if it was equipped with shim gaskets from factory, because there where blue felpro gaskets mounted. so i ordered a complete gesket kit from fel pro, as i wrote.
how much should i mill, when using the thik fel pro gasket?

and where do those heads break ,,normally,, ? mine are still useable.

thanks.

olds 307 and 403

Supposedly the exhaust side. Mill them .020".

Lars

Zero deck the block and do the heads 20

simonb.

thanks guys! will the performer intake fit correctly, after milling 0.020?

the engine is at the mashine shop now and i am waiting for the parts:

speed pro flat top 0.030'', comp cams 260h kit, all bearings, gaskets, oil pump.

should the crankshaft be balanced new with that flat top pistons, or will it not be necessary?

dont know the weight difference between the speed pro and original pistons.

greetings.

Lars

take a few days and read 2 threads, "pulling the motor" and "home porting techniques" 3A heads have some issues that can be resolved whilest there off. sounds like your gonna soop er up. this is the time to do it. and yes the performer will bolt on with 20 milled off the heads.

boese1978

you will need to have the rotating assembly balanced with the new pistons.