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Triumph TR6 - backfiring

the car started to miss when reved up and backfiring

Check points, plugs, then wires. When gas/air goes through the cylinder during a "miss" it can ignite in the exhaust - a backfire. Also, it's always more helpful if a problem is described well.
Brent B

My 72-6 was running fine until one day i decided to work on valves.I disconnected the spark plug wires as the manuel suggested and reconnected using manuel specs.Things were back to normal i thought until the engine started to cut out and backfiring until it would not run any more.My 6 starts faster cold,when it warms the motor can not catch up to starter.Just one more problem,on a test the points are not touching rotor yet the car starts? Im new at this but i have fallen in Love

Billy... you need help, we're all glad you're in love but you do need help! What did you do to the valves... do you know for certain how to adjust them? It sound like you may have had insufficient clearance on an intake valve(or two) and perhaps have even burnt them. I am somewhat confussed on your second and third statements:

"My 6 starts faster cold,when it warms the motor can not catch up to starter.Just one more problem,on a test the points are not touching rotor yet the car starts?"

If the engine turns over very fast when hot it would indicate low compression perhaps , again ,caused by faulty valve adjustments. Ability to start when cold may be due to decreased expansion of the valve train and therefore better valve seating. Whatever you do, DO NOT start it until the valves have been properly set. Better loose than too tight! You will destroy the valves and perhaps a great deal more if you persist in opperating it in that condition.

Finally, breaker points are not supposed to touch the rotor nor the distributor cap. The rub-block on the points should, however, be in constant contact with the cam.

Best Wishes , Rob
Rob Gibbs

Are you sure the plug wires got back on in the right order? It's 1-5-3-6-2-4 going counter-clockwise. It's easy enough to make a mistake - ask me how I know!

JB Fetner

Billy, if you think the rotor is supposed to touch the contacts in the distributor cap (that might be what you mean there), The spark just jumps across there from the rotor to each plug wire. Feel free to ask away, but some of your questions are confusing. Read as much as you can in service manuals or even books from the library or stuff online about how the internal combustion engine does its thing. A friend that has a bit more experience playing with cars will be helpful, he'll lovingly tell you how full of crap you are a few times to motivate you to learn for yourself.

We love to explain what we know about these cars and their eccentricities. And there are parts of them, like the carbs, that work different than most others. And there are things that could be dangerous if you don't know there's a problem (like the differential mounts). We all started just like you, fell in love with a cool car and wanted to make it work, or work and look better. The best advice is probably to be careful not to hurt or kill yourself. Again, most of us have had close calls with stupid things we've done, don't want anyone else to make the same mistakes.

So ask anything you want, just don't get offended if we say we don't understand you at first. You'll get better.


As Ron suggests, if you worked on the rocker arm/valve clearances and adjusted them too tight, when the engine heats up, the rocker arms contact the valves too early and open them causing backfires. It can also lead to loss of compression due to partially open valves.

The rocker arm/ valve clearances should be adjusted when the engine is cold. The spec for the 69 TR6 is 0.010 inches and I believe that it is the same for all the years.

Good luck with the readjustments.

Mike Petryschuk
69 TR6
Michael S. Petryschuk

Sorry, I meant "as Rob suggests". not Ron. My apologies Rob.

Michael S. Petryschuk

This thread was discussed between 18/06/2006 and 22/06/2006

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