Esteemed Listers:
What causes a '76 TR6 to stumble while accelerating after warming up?
Here's the scenario:
* Car starts easily and warms to operating temperature normally (temp
gauge works fine).
* For the first 15 minutes or so, it runs almost perfectly (only very
occasionally do I feel a slight misfire as I accelerate)
* After about 15 minutes, or if I shut the car off and restart it, the
engine is considerably rougher, missing as I engage the clutch at lower
rpms. Even in the upper gears, if there is any load on the engine
(accelerating up hills, etc), it stumbles much more noticeably than it did
after just warming up. Accelerating through higher rpms, the problem seems
to go away, but the next time I accelerate from a red light, it stumbles
again.
* Bottom line: the problem is almost unnoticeable for the first 15
minutes or so after warming up regardless of rpms or engine loading. It's
very noticeable after that at lower rpms under load.
The engine is original with a legitimate 53,000 miles on it. Compression is
about 115 to 125. It has new plugs, condenser, points, plug wires and sport
coil. Valve guides leak a bit and the carbs leak dashpot oil (through what
I assume are bad O-rings). Timing and valve adj are per spec, but I opened
the plug gap to about .30 to take advantage of the sport coil
Anybody experience this before?
Thanks.
Ian
CF57345UO
|