Don't expect big power from these heads. Poor port flow. Poor chamber shape.
Every other had chevy made is better. If you want power rob the valves and put in another head that has some potential.
Or sell them to someone else that does not know better, to fund getting a aftermarket head.
A world of difference.
It is not worth paying someone to port these heads. If it cost you money to get these heads ready
find a better head.
They will improve with generous porting but pretty much starting with any of the other head castings will
give much better end results.
The Xe274H likes compression
Find a head with a 58-64cc hi perf combustion chamber.
I get good results porting the 4416 head. The small combustion chamber is much better.
and the ports a nicer to start with and end up better too. (1.94x1.60 full port)
The 083 heads from a L98 TPI motor are not bad at all once ported with 2.02 valves.
Vortecs, camel backs, etc.
Some of the other smogger heads are not too bad with generous porting and big valves
441 487 920 etc. 882 and 462624 are the worst of the worst. really bad ex port.
Look and compare the ports to other high perf SBC heads and you will see.
This is a low perf head. The good news is someone will likely buy them just cause they have big valves.
Good for someone that is restoring a 76-80 era corvette L-82 motor.
The lame factory horsepower power rating of these L-82 motors is a good clue why these heads suck if you want power.
Last edited by F-BIRD'88; 10-14-2012 at 09:32 AM.