I'm looking for some advice re a heat problem which affects idle and
acceleration in my 76 TR6. Here's the scenario:
1) Cold start and normal highway driving are fine. Normal running is
fine under most conditions.
2) When I'm stuck in traffic and hot air builds up under the hood I
start to get uneven idle and, when I try to accelerate from a stop, the
car jackrabbits and the engine behaves like it's starving for fuel.
3) This behavior appears once the temp gauge creeps over the 1/4 mark
while idling. If I'm running on a very hot day and the temp creeps up
while air is flowing no problems appear, thus my conjecture about hot
air buildup under the hood.
4) When I turn off the engine when hot it is very difficult to start
again, until it cools down below the 1/4 mark on the gauge.
5) Carbs are balanced and mixture is correct and set when warm. The
carbs were cleaned and checked out a year ago so should be ok.
Diaphragms are intact.
I checked vtr.org and found an article related to calibrating the
temperature compensators on the carbs which described most of my
symptoms. I followed the instructions and calibrated both of them to
start opening at 115F and fully open at 140F but no change in operation
occurred.
Obviously, because the tuning is done with the hood open the air temp
never approaches stop and go conditions so I can't replicate the problem
standing in the driveway.
Here's what I'm considering:
1) Blame it on the temp compensators again but validate by loosening
the adjusting nuts so they operate at a much lower temp. This way I
should be able to replicate the problem standing in the driveway. If
this works then I'll tighten them down so that I don't approach their
opening temp until way beyond the 115F current setting.
2) I'd like to think an electric fan would help but I don't think the
engine operating temp is excessive as it never goes beyond the 1/2
mark. If I did use one I'd have to trigger it at a low enough temp so
that it ran at the 1/4 mark.
3) Plug the passage being metered by the TC's to eliminate them from
the equation and start troubleshooting elsewhere.
Any advice would be appreciated as I don't want to waste anymore time
than necessary on this. Can't drive the lbc to work right now because
of this problem which is becoming frustrating with the beautiful weather
we're getting in Toronto...
--
Mike Himelfarb
Manager, Office Network Services
Shoppers Drug Mart
(416) 490-2754
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