I concur with the suggestion that it's a vacuum leak or possibly
carburetion (not a valve problem). Agree compression sounds OK. But what
vehicle is this, anyway? An MGB should have a valve clearance of .014...
Michael Graziano had this to say:
>Oh yeah. At idle, (1k rpm) the engine is stumbling a little. Not stalling,
>just running a little rough. And when you goose it quick, there's a slight
>hesitation and a cough (though the carb, that's when I scared myself). The
>plugs are clean (no oil, and no black sooty stuff, in fact, they were a
>little white the last few times I pulled them). ANd my compression is OK.
>All within 5 except one within 10 psi (approx. 125 to 135).
>
>Could a valve be burnt? And maybe I'm still testing for intake manifold
>leaks incorrectly. What is a tried and true procedure that some of you
>folks have tried?
>
[snip]
>I checked and readjusted the valves this weekend. A few questions arose. I
>think the valve gaps were in OK shape. They were supposed to be set at
>0.010 inches. I found some that were as far open as 0.013. Does that make
>a significant difference? Is it OK to reuse the gasket as it was in good
>shape, and I used some permatex black gasket glue to help with the seal. I
>have a new one that I bought for the job, but misplaced it.
>
>Also, the intake was still backfiring. I rechecked for leaks on the intake
>manifold. Nothing found (doesn't mean nothing there). I enrichened the
>mixture a little. Now the exhaust smells a little like gas, and it still
>backfires throught the carb. Nearly scared the S#$% out of me when I had my
>hand outside the carb barrel and it backfired.
>
>I've got the timing at 10BTDC, from Bentley's and Haynes. Should I advance
>it more or less as the next test (or should I test something else first).
>And if I advance it, is that more towards 12BTDC or 8BTDC.
>
Advance would be toward 12BTDC...
--
Max Heim
'66 MGB GHN3L76149
Runs great,
looks particularly bad since some SUV clown backed into it.
If you're near Mountain View, CA,
it's the red one with the silver bootlid.
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