I recently aquired a used 455 motor with J heads heard the motor run and the price was right. Motor was in a 1948 truck with 400 transmission. Still have the orginal motor from the 1972 cutlass don't want to let Summit spec out parts (SEE OLD POST WHAT A MESS MY SON BOUGHT INTO). Looking for about 400 to 450 hp mostly driven on street. (342 Posi rear end) would like to save orginal motor anybody with a 21 year old son knows why he's heavy with the foot. Plan is to install 455 with 400 transmission know about driveshaft and switch for transmission. Any help from guys in the know would be helpful.
Thank You Have a Happy New Year

 

Just a heads up. The J heads are known for junk. They are smog heads with low flow. Not sure if they can get to 400-450 hp. Interested in aluminum heads? 10:1 compression, aluminum heads and a mild cam should put you there.

 

That might be a low compression motor ,so I would say you need pistons maybe deck the block
I would look for a better set of heads I think you could reach your goal with a stock set but in the long run it might be worth looking into pro comp heads

 

Hey Mike,


Pm'd you.