What kind of horsepower can I expect?
 

I am rebuilding my 350 in my '72 this fall. What can I expect with a freshly rebuilt motor with a new quadrajet carb and intake manifold with true dual exhaust?

300-325hp @ the flywheel assuming 9.1 compresson,stock heads (no porting), preformer intake and headers

Really? That much? I know it is hard to guess at what the horsepower would be, but I am just looking for a rough estimate. I was thinking between 200-250 HP. But if rebuilding it with performance intake and exhaust would give me that much, that would be excellent...

I'de guess about 250 with headers based on magazine dynoes of Chevy's goodwrench engines with headers and Q-jet. If using ram horn manifolds knock off about 10 to 20 HP.

The stock 70 chevelle L48 engine was rated @ 300(I think?)
the 72 was 170hp but that engine was unchanged except for the gross/net HP rating and single exhausts.....same lower end as 70 so im assuming 25 hp for the mods.....

the goodwrench engine you speek of is 8.5 to 1 (I think and the heads arent as good).....correct me if im wrong

Remember about that time they switched from gross to net horsepower ratings. That would explain the drop from 300 to 170.

I have a book of engine buildups, and they tested the Goodmark GM Crate engine at 234 HP bone stock, I believe. That worked out to 7.4:1 compression ratio, btw.

Brian

I think you might be a little confused. I am rebuilding the 350 in my '72 C20...

That's kind of a general question.How much do you want to spend.Keep the compression down to 9.1-9.5.You can get a set of vortec heads for 500 and rockers for 170.A good set of headers to help with the flow.Decide how much you want to spend and what you want from the engine.Talk to the cam manufatures,they have a lot of time invested in their cams and a lot of data to go with them.Let them know what you want and how you are buildingthe motor.Even a basic stock engine will benifit from a cam,intake and exhaust.

If you want horsepower, it's all in how you build the top end. Do some mild porting on the heads, port match the intake, run a decent cam and you'll be set. :D

The stock specs for those engines were 255 hp gross or 165 hp net.