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Advice on my heads?

2K views 15 replies 6 participants last post by  zfuel 
#1 ·
Hello. I have a 290 hp crate gm 350 sbc with a broken crankshaft. Rather than just patch it up I have opted to do a full rebuild. I want to put a little more performance into the engine without going too crazy; my target is somewhere around 320 hp or so. The heads on this engine are 1.94" intake 1.50" exhaust with 76cc chambers. Are these adequate heads or should I change them? Thanks
 
#3 ·
Real HP is in cylinder heads. Having said that, those valve sizes will support your goal. The weakness of factory heads is in the port work. In today's world it's easier and usually cheaper to buy aftermarket heads than to have a guy do port/chamber work on your heads. Your goal can be met with pistons that bump up compression to about 9 to 1 and a 270 or so duration cam with a decent intake manifold/headers. With decent heads the number jumps up to 400/425 HP without breaking a sweat.
 
#10 ·
I personally would use one of the extreme energy cams with longer duration favoring the exhaust, but your combination of parts will easily hit 325 HP. I also prefer the performer RPM air gap style although the air gap thing appears to be more form than function....but I live where it's pretty hot in the summer.
 
#13 ·
several years ago we pulled a 350 from a 78' Z28. Rebuilt with new bearings, rings, light cylinder hone, decked block .013 to square it, milled heads .030, mild 278/288 split duration Summit cam and Edelbrock RPM intake with a 600CFM Eddie carb. That motor put out 362HP at the crank.. Got great gas mileage and perfect street manners.

Thats a very budget minded build.. We spent less then $600 only reason we spent so much was one head was cracked and we went ahead to have it repaired.. i did however reshape the guide bosses in the runners..
 
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