William, I'm chiming in a little late. You seem to have gone over a lot of
ground? I cant think of too many other temperature related things you havent
already checked. But have you checked your valve timing? Your valve
clearance may be marginal and getting worse as the engine heats up. I am
suspicious of the Pertronix, but if hte engine behaves similarly with the
points, then I guess I'd leave it alone for now.
John Lumia - 1976 TR6
William wrote:
In December I took my '74 TR6 off the road to replace
the water pump, clean and coat the WP housing, and
install new aluminum steering rack mounts. I also
painted the fuel lines with aluminum-color engine
paint. Due to travel with work, I didn't get the car
back on the road until a coupla weeks ago.
Prior to taking the car off the road, it ran
flawlessly (even in 100F Houston summer heat).
I now have a problem where, after 5 minutes of
driving, the engine begins to miss. The missing
eventually deteriorates until the car is essentially
lurching down the road.
I've done the following to no avail:
1. Replaced the coil and coil-to-dizzy wire with
"known good" ones
2. Replaced the points with the Petronix
3. Disassembled and cleaned both carbs - everything
looked OK
4. Checked extensively for vacuum leaks
5. Verified both temp compensators open together at
110 F and are fully open at 140 F
6. Replaced fuel filter (cut old one in half, totally
clean inside).
7. "Blew out" fuel lines
8. New tank of gas
9. Checked screen in fuel pump (it was clear)
Other facts:
1. Distributor rebuilt last year by Bob Sarama
2. I can grab all fuel lines and float chambers with
my hands after the problems starts and they are just
luke warm.
3. Vacuum retard is disconnected, timing is at 10 BTDC
4. Pulling the choke while the car is lurching has no
effect
5. The car runs fine stationary in the driveway --
problem only appears under load on the road
6. Problem appears both at constant speed and
accelerating
7. According to Colourtune, plug color, and "lift
damper" test, mixture is spot-on at idle
8. Fuel pump is an AC-repro from TRF, 1 year old.
9. Anti-run-on valve disconnected; float chamber vents
are open to the atmosphere
10. Coolant temp stays pegged at a hair over 1/2
11. If I disconnect the fuel line before the filter
with a full tank, fuel comes out with enough pressure
to squirt me in the eye!
12. All plugs still look OK after problem starts
I'm pretty much out of ideas...any new thoughts would
be most appreciated!
Thanks,
William
|