My carbs were built up from random bits that came with all the other
boxes and I had the same problem until I took a look at the Moss
blow-up of the H type carb and noticed the oddly shaped cover cap (PN
370-130) that fits on top of the float bowl on the H4 and which
incorporates slots for venting the bowl. It really makes a lot of
difference. The engine idles better and doesn't load up nearly as much,
although it still does under some circumstances (Albuquerque is
notorious for the length and density of its stop lights).
Another improvement was switching back to the Healey version of the
chamber bolt and hardware. The set-up I was using was for an MGA. The
Healey must direct more heat toward the carb, because the rubber seals
had a very limited life in use on my car. (Ethanol may have had an
impact too.)
Bill Lawrence
On Apr 26, 2004, at 8:52 PM, James Shope wrote:
> need some more help from you 100 guys. i have become the resident
> mechanic on
> the only 100-4 in our car club. i had mentioned the problem we had on
> the hot
> day of the rally. the motor kept loading up and lots of black smoke.
> a
> better heat shield was mentioned a a possible cure. if fabricated on
> and put
> it on and also cleaned and reset the carbs, making them little bit
> more lean.
> the car ran great until the temp got to above 190 on the guage and OAT
> here in
> vegas was about 87degrees. went into home depot and when i came out
> the car
> would hardly run for about 30-45 seconds then finally smoothed out.
> happened
> again at next stop. went directly home and fiddled around a bit with
> mixture
> as it seemed as if it was flooding or possibly too lean as it would
> misfire
> and backfire until smoothing out. when cleaning the carbs i had
> noticed that
> there was no vent system or overflow tube for the carbs and just
> figured
> someone forgot to put them back on. however, my book and the moss
> catalog do
> not show an overflow tube for the carbs, only for a 100-M. i am
> wondering if
> possibly the heat under the hood is forcing the fuel into the
> manifolds since
> it can't expand and overflow out the top when it get really hot under
> the
> hood. could i be on the right track here or should i start looking at
> something else. any help will be appreciated. healeymanjim
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