[Healeys] 100-6 misfire and low oil pressure

Alan Seigrist healey.nut at gmail.com
Sat Jul 12 05:29:09 MDT 2008


Phil -

There could be several causes of this, most of them quite minor.  Bad rings
won't cause puffing sounds per se, but just puff blue smoke, so I doubt it's
your rings.

My general guess on this is when you car gets really hot, and if your
carburetors haven't been rebuilt in a while, the brass throttle shaft in the
carb will likely be worn - when it gets hot the gap on the shaft will get
quite a bit bigger and allow fresh air to get in to the mixture, causing the
car to run lean and possibly causing your puffing.  Also, if the idle
changes when hot (usually if it slows down or dies) this is likely your
problem.  The only way to fix it is to have your throttle shaft bushes
redone by an SU carb specialist.

The other potential cause is vapor lock - If I recall the fuel pump on the
100-6 is over the exhaust pipes.  the best fix is to put header tape over
the pipes for the part under the fuel pump - this will help keep your fuel
pump cool on hot days.

Alan

'52 A90
'53 BN1
'64 BJ8

On Sat, Jul 12, 2008 at 12:39 PM, <philritten at aol.com> wrote:

> I recently purchased a 58 100-6. It runs wonderfully on cool days, however
> recently we had a 105 degree day and I noticed that the usually smooth sound
> coming from the tail pipes had a "puff" sound in it on occasion. However,
> the next morning it ran fine and has since. Today, I took it on a short
> drive on the freeway and pushed it a bit. When I got home the "puffing"
> noise was back and the oil pressure had dropped to 20 from the normal 50.
> Any thoughts? Could it be rings?
>
> Thanks
> _______________________________________________


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