Anybody have any casting flaws in their manifold? Cracks? Holes?

I'm trying to nail down a problem and I think I've narrowed it down to this as being a likely possibility. But before I pull off the manifold, I wanted to see if there's been anything like this before.

 

TTT....

 

Dont forget, aluminum is much more porous than say the equivelant piece in cast iron.

Number 2 still giving u fits? Possible u have a warped deck on the intake or head? Try flatbarring it and seeing what the max warpage is....

Might want to give the propane trick a try too.

Should be able to seep inot the intake if it was porous/defective.

Also a smoke maching for late model evap testing will work if u jam rags into the exhaust and fill any remaining holes/breathers/tb/etc.

PIA but I've done it once ir twice to hunt leaks.

PS Did u completely swap out the distributor or rebuild your orignal. Just had something similiar happen on a friends car and one cylinder was dropping out. It was because they bent the distrib base when they pulled the motor. Too much clearance made the #2 cyl misfire.

later
Jeremy

 

Yeah, the distributor is brand new, not to mention that I've tried two other distributors just to be sure.

With the propane test, how would the engine respond if their was a leak? A rise in engine RPM? A smoothing of the miss?

 

Should rise or smoothen out some.

Same principle as carb spary looking for a vacuum leak. Just sometimes the propane is a lot more active in finding hard to find things sometimes.

No gaurantee, but its worth a shot I hate stuff like your experiencing as bad as you do.

later
Jeremy