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TR2/3/3A chugging TR3

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Jedi Hopeful
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When I am in high gear, and low RPM (1500 to 2000)with very slight throttle movement, I get a chugging. It seems like it would be a spark miss, because it begins and ends abruptly. If it were fuel, it seems like it would have a more gradual onset and recovery.
What is it, spark or fuel?
 
It's random. It sputters a couple of times, and goes away with a few more RPM. As if you cut off the ignition for a few strokes, but there is no missing under any other conditions. the engine is pretty darn smooth 99% of the time.
I've experienced fuel starvation a few times, and that is much more gradual in onset and recovery.
The engine never misses a beat under any other conditions, so I don't know how it could be spark.
 
This is your TR3 with SU H6 carbs, right ?
What have you got in the dashpots ? Sounds like it might be a "lean bog", which is typically much more noticeable at low rpm, comes on instantly with throttle movement and then goes away fairly quickly once you hold the throttle steady again. Thicker oil in the dashpots might be all you need.

Another place to look is excess wobble in the distributor shaft. Might be that, under just the right conditions, it flexes a little more and keeps the points from opening. Kas Kastner once described them as being made of "cooked spaghetti".
 
Carefull not to lug the engine in high gear at around 1000 rpm for too long.....Tr3 crankshafts have been known to break at the 4th journal under those conditions.
 
I'll experiment with the dashpots. These carbs are a new challenge to me. I have motor oil in there now.
As for the distributor, I'm sending it to Advanced Distributors as soon as my wife tells me that there is room on the credit card.
 
Where I was brought up, anything under 2000 RPM in top gear (40 MPH) was considered harmful lugging of the engine.
 
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