Mark, this may be a little late, just got back from vacation.
1) While your rumbling may be due to carbs, it would help to know if you have
an air pump, which were present from 1975 on. If so, then you may have a
tired diverter valve, the thing thats connected between the pump and the check
valve. Assuming you have a vacuum pump, if you try pulling a vacuum on the
diverter valve and you dont see your vac guage respond then this valve is
probably the culprit. During decelleration, the valve is supposed to divert
the air from the pump to the outside instead of sending it to the manifold
where it can ignite with the rich mixture that usually accompanies a closed
throttle. During acceleration it should allow pump air to go to the exhaust
manifold.
2) This sounds like my cars engine, which was recently rebuilt except for the
carbs. In my case I suspect the temperature compensators are gone or perhaps
the floats are gone. In very hot weather after I run it around town and it
gets hot, the car will start, except it starts hard and I usually smell gas
when it finally kicks in, indicating a rich mixture or partial flooding.
Perhaps you may have a similar problem. If you think the your spark is at
fault, try hooking up a timing light and watch the light while it cranks. If
you dont see the light flash, then you may have a bad coil (or a bad
electronic ignition unit if you have one).
John - 1976 TR6
Mark wrote:>
I've got two questions for you that I'm hoping you can help with.
1) When coming down the hills over here, I tend to get a lot of rumbling
(not
really poping or backfiring but pretty loud) and wondering if this is
supposed
to be like this or if something can be adjusted. It's really only when the
car is moving downhill with my foot off the gas pedal.
2) I've got a problem starting the car that is driving me crazy. After I've
driven it for 20 - 30 minutes and it's warmed up, if I stop briefly, it won't
start again until it cools down. This typically takes 25 - 30 minutes and is
causing significant frustration when it's a daily driver. I've replaced the
starter with a new high torque starter thinking it was the solenoid but no
luck (anyone want to by an old lucas starter ;) I've had a couple of people
suggest a heat shield may be needed by the exhaust manifold but it's a stock
manifold and I'm not real sure why this would happen to some and not others.
I've also had it suggested that it might be my ignition that is faulty but
don't know how to check this and I'm getting tired of buying parts without
getting results. One other suggestion was "vapor lock" but I have no idea on
how to check this either. I've got a new Bosch Alternator that I haven't
installed yet and plan to do so this weekend. I don't know if that will help
or not but any suggestions, as always, are certainly appreciated.
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