I sent the following message out a few days ago, but haven't seen it
show up yet. Apologies if any of you get it twice.
> I've learned a _lot_ of things from you people, and I know lots of neat
> little things about the way my MGB works. But I'm still unsure of the
> exact function of the vacuum advance. Folks say that it helps
> driveability and emissions at idle, but can somebody explain the
> physics? Is it simply a more complete burn while at idle?
>
> Anyway, I pulled the dizzy yesterday and confirmed what I suspected: My
> vacuum advance unit was frozen. Lots of WD40 and tugging later, it
> moves, but I had expected it to move a lot easier. Actually, I had
> expected to be able to suck on the vacuum hose and watch the little guy
> go back and forth. As it is, it takes a very firm push to move it.
>
> So what's normal? Is my unit shot? Do new units move easily? How much
> vacuum does the 18V make at idle? Will a functioning vacuum advance
> cure my backfiring on overrun (my thought is no; it's probably a frozen
> gulp valve...)?
>
> Once I get it working, how many degrees of vacuum advance should I
> expect at idle?
>
> --
>
> Todd "so many questions..." Mullins
> Todd.Mullins@nrlssc.navy.mil On the lovely Mississippi (USA) Coast
>
> '74 MGB Tourer in pieces this week
>
> "A life lived in fear is a life half lived."
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