I loved the sound, too. But now it is gone.
British Columbia runs a compulsory emissions testing programme in urban areas -
and my car failed. I was most indignant but then I talked to someone with a lot
more knowledge than I. When I listened this is what I learned:
The car idled roughly and while it would always start, it started inconsistently
with sometimes more, sometimes less choke. He told me that high vacuum pressures
occur at idle and even higher vacuum pressures on overrrun. If I had any inlet
manifiold leaks this is when they would show up and they would result in
missfires with unburnt fuel carried out the exhaust valve which then caused the
crackle and pop.
Spray your inlet manifold, and carbs, carefully with something like WD 40. Two
things can happen: the idle smooths out nicely, briefly, due to the lubricant
sealing the leaks for a moment, but, more likely, the aerosol propellant and
volatiles will be sucked in and cause the engine to speed up. Either means that
you have an inlet air leak.
My inlet system had about 6 leaks (vacuum lines gone hard, loose vent lines etc)
but some where also caused by grounding the exhaust system!
Alan
---------------------- Forwarded by Alan Inglis/BC Research/CA on 06/01/99 10:18
AM ---------------------------
"Andy Webster" <trunkie@hotmail.com> on 06/01/99 01:00:51 AM
Please respond to "Andy Webster" <trunkie@hotmail.com>
To: spridgets@autox.team.net
cc: (bcc: Alan Inglis/BC Research/CA)
Subject: Re: 1275 Tech. Question
I love that sound! I wish mine made it. I always thought it was something to
do with having a hot(ter) camshaft with lots of valve overlap, but that was
just an assumption.
Andy
>From: Mark Endicott <endicott@nashville.com>
>Reply-To: Mark Endicott <endicott@nashville.com>
>To: Spridgets <spridgets@autox.team.net>
>Subject: 1275 Tech. Question
>Date: Mon, 31 May 1999 19:55:08 -0500
>
>Once again I would like to ask a question of the list. I have noticed
>that my Midget has a significant exhaust crackle and pop while
>decelerating, it is most noticeable while coasting in top gear on a long
>downhill run. I assume that there is more unburned fuel in the exhaust
>system when the engine is generating the same rpm from gravity without
>the need to produce as much power. My question is this exhaust crackle
>and pop causing any damage to the engine, and is is possibly timing or
>carburetor set up that is causing this. It is becoming more noticeable,
>especially when the engine is not yet up to normal operating
>temperature.
>
>Along the same lines, my car has a very cold nature, even in the summer
>the engine seems to take four or five miles to smooth out and run well.
>Yet it starts without hesitation on the first spin of the starter with
>only a little choke on the first starting and none the balance of the
>day.
>
>The air pump is gone and the exhaust ports are plugged, no noticeable
>air leaks in the exhaust or manifolds. Runs fine otherwise.
>
>Thanks Again
>--
>Mark
>1970 Midget
>Nashville, TN
>
>http://members.home.net/mendicott/midget.html
>http://www.NashvilleTN.org/NBCC
>
>
>
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