<VV> Plug gap

Tony Underwood tony.underwood at cox.net
Sat Nov 6 13:09:33 EDT 2010

At 11:24 PM 11/5/2010, Stephen Upham wrote:
>I decided to look at the plugs because of what seems like excessive
>gas smells while running.  There are no detectable gas leaks anywhere
>in the lines.

I seriously doubt that a gas smell could be caused by plugs unless 
several were not firing and gasoline fumes were going out the 
exhaust.  If the engine isn't misfiring, you have another issue 
besides plugs.

>The gap on the plugs is at .030.

Slightly narrow... the gurus at GM said .035 but it shouldn't make 
much difference.   Depending on how much spark you have, and the 
demands of the engine (compression and cylinder filling capabilities) 
you could get away with less gap than that, or more gap, and not 
notice a difference in the majority of driving.  Some of the smog 
years engines were using very hot spark and plug gaps up to .085 in 
order to light a miserably lean mixture.

Your plugs at .030 are likely fine as-is.

>I have almost
>everything new(ish) on the rebuild including plugs, distributor cap,
>Seth's plug wires, Pertronix I, Flamethower coil,


You could, just to hedge your bets, open the plug gaps to about .04 
or maybe even a little more, and take advantage of that hot coil and 
snappy ignition.   It could make the engine run smoother in 
situations where a stock ignition could misfire.   With your ignition 
and coil, it wouldn't when used with a wider plug gap that would 
light a mixture that the stock ignition might balk from.

Still... I don't think your gas smell is being caused by anything 
involved with your plugs.

>and rebuilt carbs.
>The advance is 29 degrees BTDC.  I'm using 93 octane.  Should I widen
>the gap and/or look elsewhere?

Is that 29 degrees *initial advance*?   If so, I think that's too 
much unless you're running open-chamber smog heads (which suck, by 
the way).  Even then, it's pressing the edge to run that much initial 
advance.   I'm surprised it's not pinging.

Now:    WHERE is the gas smell most evident?  Is it coming from the 
engine exhaust, from inside the car through the heater/air ducts, or 
is it coming from outside the vehicle?    Is there an electric pump 
on this car?   If so, is IT leaking?   I'm wondering if you have an 
unspotted fuel leak someplace instead of an unburned mixture thing 
working its way out the exhaust, although that's still possible but 
not very probable.


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