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Triumph TR6 - pinking on longer trips

My 76 six has started to run roughly after highway driving lasting more than an hour. It runs fine in city driving, but once I have run at 3000 to 3200 rpm for about an hour, the engine starts to run roughly and miss when accelerated. I have read that engines that were built to run on leaded gas can exhibit this trait on unleaded as the valves heat up. Was the 76 built with heads that can tolerate unleaded fuel or should I be using an additive? If so, any recommendations. I suspect it also could be a timing issue. I set the timing with a timing light after removing and plugging both ends of the vacuum advance(permanently). In that configuration, what is the best timing setting? Thanks for the help. This board is a great resource.

Mark Hauck

For all the opinions regarding leaded/unleaded gas & heads consult the archives. I believe the TR6 was built for leaded gas and the head/valves should be upgraded when rebuilding the engine, but not as a priority issue. I use the timing light for information only and set the timing based on performance tests.

If my '71 had the problem you describe, I'd try a fuel additive, but I suspect something else because you start your explanation with "... has started to...".

EC Smith

Pinking or pinging is more a noise than a misfire. I would suspect a rich mixture, does it smoke (sooty black)? How do the plugs look? Just a guess at this point. You can try advancing and retarding a little to home in on the timing. It would be nice not to need additives, try to find the source of the problem first. May be as simple as clean points and a little grease on the dizzy cam, or a new condenser.

Thanks for the responses. The engine clearly is misfiring as I can feel it hesitate and lose power when I attempt to accelerate. I will play with the timing first as I reset that after installing an ignitor pointless ignition. I will also check the plugs. I will post an update after further investigation.
Mark Hauck

Starting to sound like an advance problem.

For whomever cares, I thought I would update this link to let you know what I found. I pulled the plugs (Champions I installed in April) and found that they were covered in black soot indicating an over rich fuel mixture. I now plan to rebuild the carbs over the winter. In the meantime, I installed new Bosch Platinum plugs. My six has never run sweeter. Amazing change. I will still rebuild the carbs, but you would never know they need it now.

P.S. I saw on another link that someone recommended gapping the plugs at .40, instead of at the factory recommended .25 if you were running the Petronix electronic ignition. I am, so I tried the larger gap with the new plugs. The engine would not even turn over! I went back to the .25 gap setting and it started right up and runs like a dream. Just thought I'd pass that along.

Mark Hauck

Congrats on your success on sweetening the TR! My TR4 was running like crap for a while today, too. I think the soot finally got burned off and it ran great the rest of the day. Or a piece of dirt made its way through the jet, who knows. Fixed itself before I made it back from the gas station, which left more time to inhale red sanding dust, ugh.

Try a gap of 30 or 35 0n the plugs. Also,the mixture can be adjusted with a special tool available from all suppliers (Z S adjusting tool...less than 10 bucks).
Rick C
Rick Crawford


You've gone down the same road as I, more or less. I had a Crane XR-700 which is roughly equivalent to the Petronix. It couldn't run right at high gaps, but ran fine at .030 go, .035 no-go settings.

You'll need a higher energy system to use bigger gaps. I ended up with a XR-3000, with a 0.040 go, .045 no-go. Lucas Sports coil here. The higher energy unit makes a big difference! There are comparable units for Pertronix, I think, and those users will chime in. Also, the MSD units are good, too, from what those users say. Bottom line is that a good high energy ignition will make a difference.

Brent B

This thread was discussed between 03/08/2004 and 25/08/2004

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