Solex carburators

[Richard Hoffman]

I'll take a look through my spares and see if I have a condensor.  This may
be the last piece that I haven't replaced.  Forgot to mention that  the coil
is new as well.

Here's compression readings from front-to-back: 200, 202, 205, 205. The
manuals all list recommended compression between 200 and 220 psi.

The valve gap is somewhat hard to set, as the recommended setting is .002"
and my feeler gauge doesn't go that low.  If that were off, then my
compression would suffer, wouldn't it?

Here's a thought, tell me if I am WAY off.  This car uses a hydraulic cam
chain tensioner that functions off of engine oil pressure.  If this were
faulty, the valve timing could be affected, correct?  If the valve timing
were incorrect, then the intake valve could be open when the spark fired,
causing the backfire.  I personally don't know how to set valve timing, and
the timing cover is almost impossible to get to with the motor in the car.
I'd like to avoid pulling it.

Here's the tricky part: the car will run smoothly at around 3000 rpm.  If I
give it a miniscule amount of throttle, it will slowly and jerkily build
revs and then voila! it runs smoothly.

This thing has been a real corker for me, as it ran SO well for a week after
the rebuild and now nothing I do makes it better.

Thanks for all the help!
Richard
----- Original Message -----
From: "Per Lindgren" <lindgre at online.no>
To: "Richard Hoffman" <billzcat1 at hotmail.com>
Cc: <quattro at audifans.com>
Sent: Wednesday, August 06, 2003 1:53 PM
Subject: Re: Solex carburators


> This doesnt sound right, Richard. I have zero experience with old Audis
> but lots of experience with old VWs (and an old Mazda) but I have never
> seen backfiring up through the carb that is caused by the carb itself
> being out of tune. There has to be a reason for the spark or ignition
> flames to reach the air/fuel mixture outside of the closed intake valve.
> Have you checked the valves for the correct gap? Have you run a
> compression test to see if there might be a burned valve seat? Or
> perhaps a bent valve? Thing like these causes the combustion to run out
> of the cylinder and pop inside the carb, but usually it is because the
> timing is off.
>
> PerL
> 87 Cq
> A couple aircooled VWs
>
>
> Richard Hoffman wrote:
>
> >Hello, I am getting tired of dicking around with the carb on my 100LS. I
> >rebuilt it and the car ran positively great for about a week, then slowly
> >ran worse and worse and started backfiring up through the carb.  I've
> >already verified that the timing is correct and the vacuum and mechanical
> >advances work on the distributor.  Points and dwell are properly set.
Choke
> >is working correctly and is also properly set.  Plugs, wires, cap, and
rotor
> >are new.  Fuel filter, lines, and pump are new and the gas is good and
> >clean.
> >
> >My 100LS club only has about 10 members, and one of them said they had
the
> >exact same situation because the Solex carb is so picky about being set
up
> >correctly.  Does anyone A) have any other suggestions or B) know a solex
> >carb specialist where I could send it off to be properly set up?
> >
> >Thanks in advance!
> >Richard
> >90 CQ 221k
> >70 100LS 47k
> >
> >
> >
> >
> >
>
>