blown head gasket

[swampy2646]

i recently repowered with a 5.7 long block in a 1991 maxum 2500 scr. i put an agressive cam(300 hp) with a new high rise intake, a rebuilt q-jet, new risers and manifolds. upon initial test run, the head gasket blew between cyl. 2&4. after 10 mins. the builder claims the engine was running lean. i pulled the head and sent it to a local machine shop to be checked out. i pulled the other head and changed both head gaskets. after having other problems(previous posts) i got the engine running great. last week it started to run a bit rough and sputter. i did a compression test and found : 2 (50 psi) 4(50) 6(90) 8(150) the other side was within specs. i didnt pull the head yet, but im assuming the gasket blew again. is it possible to be running lean, the plugs looked good and there is never any pinging. if so what causes this condition?

 

[kevincave]

Re: blown head gasket

in my experience with chevy small blocks and racing, too lean would burn a hole in the piston.

 

[Bt Doctur]

Re: blown head gasket

Improper torque pattern or ft/lbs, leaking intake manifold joint, 1 side of the carb is lean

 

[swampy2646]

Re: blown head gasket

tripple torqued to specs, brand new intake sealed and torqued, i guess its the carb. unless the block isnt decked right?

 

[searay3]

Re: blown head gasket

not hard to check. Straight edge and a feeler gauge. Check the head too. Lean should show on the plugs. Run it hard, stop, (don't shut down right away or yu may swamp the motor/boat) pull a plug on the suspect side and see.

 

[TilliamWe]

Re: blown head gasket

in my experience with chevy small blocks and racing, too lean would burn a hole in the piston.

And in my experience with a Vortec SBC in a boat, it tulips valves first.
Have the valves in the head checked first.