Gazelle -- Poor cruising speed

"Jonathan Barnes" wrote in message

>
> "Peter Dohm" wrote in message
>
> > I just "discovered" this NG a couple of days ago, and noticed a long ago
> > thread regarding a Gazelle kit car with a 2.3 liter engine and manual
> > transmission which had a very low maximum cruising speed--around 50 mph.
> > The discussion centered on the possibility of changing the final drive
> ratio
> > to require less rpm for a given road speed.
> >
> > I am curious whether the problem was ever resolved; because that really
> > looked like exactly the wrong solution for a two reasons:
> >
> > 1) Nothing is geared that low, and kit and custom cars nearly always
> have
> > oversize tires (compared to the donor) which results in a sort of
> > overdrive--whether you want it or not.
> >
> > 2) It was not uncommon for the early belt driven overhead cam engines
> to
> > advance a tooth or even two on a very hard shift, and that can cause the
> > symptom described. It would not have been uncommon for a less than
> > knowledgeable owner of something like a Pinto to have that happen,
correct
> > the ignition timing, and eventually give up on the car which still ran
> like
> > it was old and tired.
> >
> > It does seem improbable that any of those engines are still running with
a
> > belt old. However, if the present owner never did any serious engine
> work,
> > there is no telling what the previous owner may have done. Possibly
even,
> > very carefully, replaced the belt with the sprockets in exactly the same
> > (incorrect) relationship!
> >
> > Just very curious.
> > Peter
> >
> 2.3 l..... was it a diesel....4000 max rpm....and a petrol gearbox / rear
> dif ???
>
>
> --
> Regards Jonathan
>
> remove AT to reply
>
>
I doubt it. The first response to the original post supposed that the
Gazelle kit had been built on a 2.3 liter Ford Pinto drivetrain and the
subsequent conversation never denied that supposition, so I presume that the
2.3 liter gasoline engine was used.

However, the Pinto engine was among the first to use the belt driven
overhead camshaft and Ford also that engine and some close derivatives in
several other models worldwide. The early engines had a square toothed belt
and spring tensioner, and it was not uncommon for an overly enthusiastic
driver to inadvertently advance the cam when "dumping" the clutch at high
rpm. The usual consequence was that the engine would idle and run normally
at low rpm, but would "run out of wind" partway through what would normally
be its midrange. In fact, it might make the rpm range similar to a diesel;
or even a little lower. Therefore, a Pinto with that problem might had
struggled to exceed 70 or 75 mph; while the less aerodynamic Gazelle might
have difficulty exceeding 50 mph as stated in the original post. Shifting
down would only slow the car down further, since the cam advance would then
strangle the engine even more--as though the driver lift his foot partway
off the accelerator.

As development of that class of engines continued, a locking device was
added to the spring tensioned and the belts now have rounded teeth; so that
the problem is now very unusual except on high mileage engines with badly
worn tensioners. BTW, I had to have the tensioner replaced on a Chrysler
2.0 liter engine along with the belt, because the locking device had failed,
although mine had not yet skipped timing.

So, all of the described symptoms fit and I was curious as to the outcome if
the OP is still reading the group.

Regards,
Peter

PS: I don't know whether square toothed belts are still used on the early
engines that are still running, or whether round toothed belts or a hybrid
are now used.
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