compression?

[Toylet]

hey all~
i have a 1980 350 engine from a truck, and believe it's compressions is 8.5:1...and runs beautifully...I have a set of 1967 283 heads in the garage that are in pretty good shape...will installing those heads help me edge a few more ponies out of the 350? The 283 had a compression ratio of 9.25:1...pumping out 50 more horsepower than what i have now (145 vs 195)...am I having a pipe dream...any input is graciously appreciated.


Toylet

[amac209]

port them out and throw in a cam. should wake up the truck a bit. i'd also get a edelbrock intake and k&n filter. if you have a decent Q-jet carb without too much emissions crap i'd keep it most people don't know a q-jet will flow 750CFM you should be able to get all this stuff for about $350. i assume you have 72cc heads now and the 289's are 64cc should make a difference any boost in compression makes a big difference.

[quaddriver]

Originally Posted by Toylet

hey all~
i have a 1980 350 engine from a truck, and believe it's compressions is 8.5:1...and runs beautifully...I have a set of 1967 283 heads in the garage that are in pretty good shape...will installing those heads help me edge a few more ponies out of the 350? The 283 had a compression ratio of 9.25:1...pumping out 50 more horsepower than what i have now (145 vs 195)...am I having a pipe dream...any input is graciously appreciated.


Toylet

well, post a casting number, but im betting that the 283 heads have small 172/1.3 or 1.5 valves, they dont have seats for non lead gas, they will likely raise compression to the 11:1 range on a 350

it would be better to find a set of mid/late 80's swirl port 350 heads if you are keeping the carb, or get a set of L31 vortecs

[Toylet]

hhmm...the heads are at home, so i can't get a casting number...but valves are the 1.71 and the 1.5.
So i can't use those heads due to the valve seats being meant for leaded gas? is there any way around that..such as milling them?
thanks
toylet

[quaddriver]

Originally Posted by Toylet

hhmm...the heads are at home, so i can't get a casting number...but valves are the 1.71 and the 1.5.
So i can't use those heads due to the valve seats being meant for leaded gas? is there any way around that..such as milling them?
thanks
toylet

the valve seats can be replaced, and at the same time, opened up for larger valves - 1.7 is too small for a 350 revving over 4000, but given the cost of this and given that the chambers are likely so tiny it will raise compression past a point you can deal with - there exist many heads on the market new or used that will be cheaper, raise compression slightly and have better ports and larger valves.