TR2/3/3A TR3 running rough

[tad]

The car runs smoothly up to about 3000 rpm, then acts like it has water in the fuel...coughs,misses and backfires, till about 3800 rpm and it smooths out again. Ideas.... please.
Thanks!

 

[TR3driver]

My first guess would be excess shaft wobble in the distributor, perhaps combined with the point gap being off.

Remove the dizzy cap, and see how much you can change the point gap by moving the rotor/shaft away/towards the points.

Or, a better test is to hook up a timing light and watch what happens to the timing mark as you run the engine up to the range where it has problems. If the mark starts dancing around, you know you're on the right track.

Also worth checking the sediment bowl ... it might really be water

 

[eschneider]

The car runs smoothly up to about 3000 rpm, then acts like it has water in the fuel...coughs,misses and backfires, till about 3800 rpm and it smooths out again.

- so below 3000 it's ok, and above 3800 it's OK?
- Is this under gradual / constant throttle?
- Stock SU H6 carbs? DGV weber? DCOE?
- Is this a sudden thing? Had it been running well prior to a recent tank of gas or work done?

Sounds weeeeeird, especially if it's stock SU carbs.... If it's webers I'd say something is amuck (pun intended) in the transistion circuit ("idle" jets)

I would definitely pursue TR3driver's advise - but my gut is saying ignition wouldn't be the culprit if all is well over 3800 RPM.....

With sincere sympathies to your misfortune, this will be an interesting thread to watch. Keep us posted!

 

[tad]

Thanks for the advice (and kind words).
I'm taking the car in today for routine work and will have the fellow try your suggestions. BTW, when I described the problem, he immediately thought of points/distributor.
I'll let you know.

 

[Mickey Richaud]

Hello, Tad -

Noticed you're in Dowelltown. I'm not too far from you; "Tinkerman" is even closer - in Crossville.

 

[TR3driver]

but my gut is saying ignition wouldn't be the culprit if all is well over 3800 RPM.....

Haven't you ever had a vibration that goes away above a certain speed? Same principle applies to the dizzy shaft ...

 

[eschneider]

but my gut is saying ignition wouldn't be the culprit if all is well over 3800 RPM.....

Haven't you ever had a vibration that goes away above a certain speed? Same principle applies to the dizzy shaft ...

Wooden-ta-thunk it in a distributor.... but I'm staying tuned in hopes of learning something for free and without pain.