i recently purchased a 82 camaro z28 with a 400. i have a set of world sportsman 2 heads with new double valve springs. rated to 600 lift. they have been milled to 62cc chambers and have 202 / 160 valves. i was wondering on some ideas for a build up for this motor and am looking for around 450 to 500 hp. any suggestions will be greatful.

 

If the 400 has flat top pistons, the compression ratio will be way too high for pump gas using 62cc heads. (over 11:1++) (race gas).. If the pistons are dished (18-22cc) you'll be fine. you want 10:1 compression for pump gas.

What pistons are in the 400? Do you want to get a flat tappet or roller cam?

Sportsman II heads are good quality heads but the out of the box flow is not near what it could be. They need full porting. Remove a valve and look at that huge valve guide boss blocking flow in the bowl. Compare to pics of ported or cnc heads.
Out of the box flow varies from 224 to 240cfm depending on the valve job. Can go over 300cfm with proper porting.
You're looking for 260 cfm or more.

For 450hp use a cam with about 242/248 duration @.050" (.520+lift) and a performer RPM intake
for 500+hp use a 255/260 duration @.050 cam. (.550"+ lift)
and a victor Jr intake. minimum 750cfm carb.

 

i haven`t got into the engine yet. the guy i bought it from said it had flattop pistons. i was planing on running a 3000 stall with a built trans. and have the power band of the cam from 2500-6500. i really haven`t choose a cam yet.

 

Flat top 400 pistons and 62cc heads will give you way to much compression ratio for pump gas. you'll need to get friendly with your local race gas dealer or run it on Methanol. You could swap pistons or use different large chamber 76+cc heads. What heads are on the motor now?

Do you want a "race gas" motor?

 

it has a set of 350 heads on it now. i plan on takeing them off. i will probably have to change pistons since i want only around 10 to 10.5to1 compression. so i can still run it on the street.

 

look for around 9.5:1 dynamic compression