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TR2/3/3A TR3 Missing [running rough not stolen!]

Royal_58

Senior Member
Offline
Just came in from the garage trouble shooting the TR3's rough running engine.

The engine is missing at low RPM (900 to 1500)consistently High RPM (3500+)intermittently
Cold high RPM smooth
Warm high RPM rough <span style="text-decoration: underline">sometimes</span>
Acceleration is always smooth

The step by step actions are listed below. I'm making a change one at a time to ID the problem. I'm stuck on the ignition system and will try the carbs next.
1. Replaced wires- no fix
2. Replaced MGB cap with correct cap - no fix
3. replaced Rotor - no fix
Next steps:
1. Replace points
2. Replace coil
3. Move to carbs.

QUESTION
The plate that the points are mounted to wiggles. It moves up and down making the little red plastic cam follower face change from being parallel to the cam to being at an angle.
[img:left]C:\Documents and Settings\Duke\My Documents\My Pictures\58' Triumph[/img]
Is this correct? Seems that should be a constant "flat" against the cam.
How can this movement be taken out of the points if it not to be there?
Any suggestions on where to go next?
 

TR4

Jedi Knight
Offline
Re: TR3 Missing

Have you checked the timing? Also check to see if there is one of the spark plugs that may not be firing properly.
 

Banjo

Yoda
Country flag
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Re: TR3 Missing

Phew! from the title of the thread I thought your car had been stolen....
Anyhoo... I think you're on the right track. Do the points and condenser (although a bad condenser usually kills acceleration). the plate tends to have some play in it, usually it dosen't move that way when in use. don't let that get you bent out of shape.
Make sure that the flexible ground wire from the moving part of the points plate to the dizzy body is in good shape, in not, that can cause intermittant ground issues as that plate moves back and forth.
good luck Guv'na
 
OP
R

Royal_58

Senior Member
Offline
Re: TR3 Missing

Sorry about the title, I'll try to change that.

Timing checks OK and the 4 spark plugs look the same in color, originally had some differences in the #2 cyl but with the changes it seems to have resolved some of those. I'm still thinking there are a couple of issues here I'm trying to purge. New plug wires have made the high RPM roughness intermittent. Others have told me the carbs need cleaning. I'll try that while I'm waiting for the back ordered coil.

Going for a drive, maybe it'll work itself out :smile:
 

TR3driver

Great Pumpkin - R.I.P
Offline
Re: TR3 Missing

What does the timing mark look like under the timing light, as you rev the engine up? If the point plate is wobbling around, it will show up as spark scatter.

There needs to be some play in the upper plate, so the vacuum advance can turn it; but not a lot. Remove the assembly from the dizzy, disassemble, clean and lube; then you can see how to bend it slightly to reduce the clearance if necessary. While you are in there, inspect and lubricate the mechanical advance as well, including where the cam turns on the inner shaft.

Banjo's remark about the ground wire is on-target as well. I like to check both wires (both the ground and the hot wire to the side terminal) by connecting an ohmmeter, while I gently tug on the wire, to ensure it's healthy under it's insulation (never did understand why they put insulation on a ground wire).
 
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