Backfiring then quit

Recently overhauled my 77 MGB engine. have 2000 miles on it. On a trip last weekend at about 4000 rpm's it started to backfire and got progressively worse as I went on. pulled the head off thinking that it is the head gasket, no anti freeze in the oil, the gasket was all intact, carbon build up in cylinder 3 & 4 was excessive and also in # 1 .I torqued the head twice, first on buildup then after 100 miles was on it. Any Ideas would help...
Skip
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Skip Charette wrote:

Check if the inlet manifold is tight. Mixture lean and sucking air.
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weekend at about 4000 rpm's it started to backfire and got progressively worse as I went on. pulled the head off thinking that it is the head gasket, no anti freeze in the oil, the gasket was all intact, carbon build up in cylinder 3 & 4 was excessive and also in # 1 .I torqued the head twice, first on buildup then after 100 miles was on it. Any Ideas would help...

The car was backfiring and you pulled the cylinder head off?? That's a little extreme. Head gasket issues are usually indicated by blowing white smoke out of the tailpipe, not backfiring..... Backfiring can be caused by a number of things - take a look at this, found it by using Google - http://en.allexperts.com/q/Classic-Antique-Car-2542/exhaust-backfire.htm
Dan D 2 MGB's Central New Jersey USA
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