how much would a 350 or 400 have with the same setup and maybe a little porting and more cam?
how hard are 400s to find?

 

How much would it have.. of what ?

 

this was meant to be a reply sry.

 

Considering most engines can easily get 1 HP per cubic inch and still be streetable, a 400 will get 50 more HP than a 350 with a similar setup just because of the increased displacement.

GM stopped producing 400's in 1979 or 1980. Since there haven't been any new ones made in over 20 years they're getting hard to find but not impossible. You can still find them in pickup trucks and vans from the late 70's.

The biggest improvement to a 400 is heads. Fatory 400 heads are junk. GM never produced the 400 as a performance engine. You can buy the engine cheaper as a short block if you pull the heads off at the junkyard and leave them there. Or you could find a set of target master 993 casting heads and bolt them on before coming out of the junkyard with the engine. The heads will only need the steam holes drilled into them before they could be used.

 

What are target master 993 castings? I have 993 casting heads that i pulled from the junkyard on my 350 long block, are they the same? It was a 73 350 block and probably 73 heads.

 

Target Master is the GM replacement engine. They're just easier to find. If it's a Target Master 350 then you can be sure it has 993 castings. The 993 castings are good heavy castings. They're 76cc smog heads but the castings are much better than other smog head castings. The 76cc chambers will unshroud the valves plus you can easily have 2.02/1.94 valves installed. Increase compression ratio with a different piston instead of the smaller chambers.

Most of the 400's have 882 castings and just about every one of them will be cracked because of the thin walled casting. The chances of finding a cracked 993 casting is low.

 

I thought the 993 heads were an advertised 75 cc chambers.