4.7 stroker header leak frustration

[superstingray77]

4.7 stroker jnstalled in 99wj and runs good. One major frustration, header leak I have tried to fix. Header is a quality built 1/2 inch laser cut with fully welded seams both inside and out, flush surface. Dual cat design, 4 O2 sensors, 2 pre and 2 post cat. The leaks are on cylinder 3 and 5 at the bottom of the ports. They are made for 99 up w the 0331 style head. However the ports on the header match the pre 0331 larger ports. I can't see how this would cause a leak as the head is flush and so is the header flange 2 of the bottom bolts are a real treat to reach even so I think I got them tight. I have changed the gasket from an mls to a felpro and damned noise stayed the same, really having a nice new cammed up motor sounding like a putting junker. Any thoughts should I ditch the header for another model?

[SilverXJ]

For what year is the gasket you are currently running for? When installing it did you use any copper RTV on it? Are you 100% sure that none of the header pipes are making contact with the intake manifold?

[superstingray77]

Hey Silver,
The intake went on last without any clearance issues, nothing touches it.
The gasket is the 99-up gasket with a reproduction Alabama 0331 head thats ported with larger valves etc.
I have a bad 62xx casting off a 96 Cherokee here that used for comparison and the 99 up gasket seems to work fine for coverage and plenty of sealing area....
I almost gave in to using the RTV on it but didnt, perhaps i should but figured that would be a bandaid and just blow out after a few weeks. Any experience with that stuff holding long term? I was debating an old trick I use building olds motors where the center cylinder exhaust ports only use 3 bolts (like the jeep) to the flange in place, I would use 2 header gaskets glued together, however with the intake involved I was afraid of possible seepage/fuel soaking over time wiping out the intake portion.

I can post pics of the gaskets but not certain how to do it here.

[604rail_king]

I was just going to suggest double up the gasket with some rtv. I wouldn't be concerned remotely about fuel seepage.

[SilverXJ]

I would try an earlier gasket since the header ports are larger to match the earlier head. The lower sealing part of the later gasket may actually be sitting inside of the header flange ports. I frequently use a light coat of Copper RTV on the gasket.

[superstingray77]

Silver, I thought the same thing, i would have mod the intake ports on the older gasket, i purchased one to match up and it lines up blocking about 1/8-1/6th of the port at the top. easily trimmable.