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| | | | Joined: Mar 2008 Posts: 283 'Bolter | | 'Bolter Joined: Mar 2008 Posts: 283 | My 235 (which is allegedly original) in my 56 smokes at traffic lights, generally after a run, but not noticeably during. Friends who seem to know tell me that is most likely from weak or deteriorated valve seals. Engine compression runs 140-150 so the lower end they say is most likely okay, just rebuild the top end. Any thoughts?
Dale | | | | | Joined: Jul 2004 Posts: 5,708 'Bolter | | 'Bolter Joined: Jul 2004 Posts: 5,708 | Dale,
My thought would be worn out valve guides more than defective valve stem seals. The stock 235 had very mediocre seals to begin with. I think this is what your friend was alluding to.
It could also be a bad ring or rings that don't show up when roaring down the freeway as the smoke is dispersed. Your compression values are great, but a score down a cylinder can allow oil into the combustion chamber.
A top end rebuild with knurled guides or new guides would probably solve the problem, but be aware that sometimes a new top end will exacerbate any wear in the ring area and you might end up with a real smoke bomb. This doesn't always happen though so It is probably worth the effort.
Stuart | | | | | Joined: Mar 2008 Posts: 283 'Bolter | | 'Bolter Joined: Mar 2008 Posts: 283 | Many thanks Stuart you have pretty much verified what the fellow at the cylinder head shop I visited today indicated. He said the original seals weren't much anyway and that the guides were much more suspect in his mind. He said the same thing on the rings that you did, nice that you have good compression, but you can still leak through an oil ring, and/or have cylinder wall damage that could cause smoking as well. Won't know until the cylinder head comes off of course, so will start at that end and see where it leads. Thanks for what you offered Stuart - it started me on the trip to the cylinder head shop (the guys there were great too and showed me a lot of examples of what to look for) and it definitely has me going in what I think is the right direction now.
Dale | | |
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