I recently pulled the heads off and fixed a valve seat that was bad. I had the heads machined and trued up the block to match- within .001/inch. No problem there. When I put it all back together, fired right up! Only thing is I now have a Super loud exhaust leak. I checked and the stock header was cracked - as they are prone to do, being cast iron and all, so I replaced them with a set of stainless. I fired it up and...no change! Still a loud leak. I checked all bolts, repositioned the header and collector 2 or 3 times now with no change. I replaced the manifold gaskets twice- all with no change. It sounds like it is coming from the drivers side manifold area but it is hard to tell for sure.

I can't find where it is at and at idle it goes almost completely away. Under load it is way loud.

Any tips or advice would be greatly appreciated

Thanks

CJ

 

I'd try a small mirror tool that extends on a rod/handle. Use a flashlight and look for discoloration from a leak. It might be a defect in the stainless headers, maybe where the flange mates to the head. Check the old gasket from the last replacement for signs of a poor seal.

Hate to say this, but headers tend to have more problems than the cast manifolds. Keep an eye on spark plug wires, and how they are/were shielded from heat.

 

Thanks for the info. I'm thinking it's more than an exhaust leak ( in addition to, actually) leaning towards piston slap also.

 

Try adding Lucas oil stab -- If the noise is noticeably less, that likely indicates excess clearances somewhere like rod bearings or piston/cylinder.

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