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Old 09-07-2010, 06:24 PM
dgcantrellsr dgcantrellsr is offline
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If they are (very old) replace them,new one's are not that expensive. And while you got them off check for valve guide slop. Also may have lobes going on camshaft.


Quote:
Originally Posted by fred56
I was out today and on the way back my SBC started clacking(rocker arms?) and as soon as I went to an idle it stopped clacking. What it seems to be doing is back firing/missing out the exhaust. I checked the timing/wiring/vacuum leaks and what I have come to the conclusion is that one or more of the exhaust valve springs are getting weak. At idle it purrs like a kitten but at 2000 rpm and up it pops/misses thru the exhaust not the carburetor. If the springs are weak can you compress(move them at all) them a little by hand? It seems to me that the springs are weak. They are very I mean very old. How can you measure spring pressure without taking them to a machine shop?
Thanks - Jerry
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