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Triumph TR6 - Timing Again....

I've been trying to fine tune the timing but I am getting disasterous results. I use 4 BTDC as a start point and retard the timing (turn the distributor in the opposite direction of the rotor direction: clockwise) and run it. But still, the backfiring persists. Today it got so bad that I had to find a position where it would run smoothly but then I could not take it over 2000 rpm.

Other notes: it was a very hot muggy day. The engine has been running at 3/4 hot on the temp guage. Rain was involved as well.

Help!!

I have the distrib off now and will tear it apart tomorrow. Perhaps the low tension line inside the distr. head? Is it electrical? The carbs seem okay and the plugs are the proper brown/white colour. Fuel consumption is not so good (18-19 MPG highway). Will investing $180 in the electronic ignition system restore my sanity?

Any thoughts would be appeciated.

John (Calgary): From your previous note, I assume that you retard (turn clockwise)?
Bryn

Have you invested 30 bucks in a timing light?
Brent B

Yes, 4 BTDC by the timing light.
Bryn

Advance/retard. Clockwise for advance, right? So to take it from persay 4 BTDC to 8 I turn the distributor clockwise. I'd better make certain I'm not completely out of line here.
Bryn

Yep - CW is advance.

I ran about 6 deg BTDC on mine, vacuum retard only (is that module good?), but didn't like the upper end response.

Centrifugal only, ran about 8 BTDC.
Brent B

I've been running my 70 at 12 BTDC with timing light 850-900 rpm, retard plugged while timing.
Ian Kinaid

Hi Bryn
I think you might have an electrical problem with your ignition as timing doesn't usually cause backfiring unless it is miles out.
I don't think there is any point in setting the timing with a strobe to a book setting as the petrol nowadays is different volatility from when our cars were originally made.
What I do is set it it roughly till the car is running reasonably smoothly and then take it out to a quiet road and keep advancing it slightly till the engine pinks [knocks?] under load in a higher gear then retard it slightly. This gives reasonable performance and economy but obviously needs the ignition & carburation to be working correctly
Hope this is of some help
Ron
R. Algie

Bryn--You're probably tiring of folks' suggestions, but here are a few more:

--Replace the distriubtor's rotor. Bad rotors have messed with me on several occcasions. I carry a half-dozen of them in the boot at all times.
--Verify good fuel delivery to the carbs by cranking with carb hose detached.
--Are you sure one or both of your carb needles hasn't disengaged from the adjustment screw and bottomed-out on the bridge? Verify by trying to go full rich with the hex; if you never stop turning CW, that's what happened.
--Do you have new or old ignition cables? If they're green, get rid of them now.
--Running at 3/4 on the temp gauge is not normal unless idling for an extended period of time during hot weather.
--Does removing the vac hose to the distributor retard capsule increase the idle (it should)?

Keep us posted.

Rick O.
Rick Orthen

I'm in the middle of diosassembly and I suspect the vacuum r4etard isn't quite right. How much moveemnt should I see when a vacuum is applied? And would a malfunction vacuum retard affect misfiring under load? (I think not as it was installed to reduce fule consumption during deceleration?)
B
Bryn

Okay, I think I've almost got it sorted. The engine was overheating and as a result, the points were screwed up (thus the backfiring). I adjusted them back to .015 and its running better. Still misfiring occasionally particularly when its cold but getting better. I'll go for the pertonix next year.

So now; why the overheating? I'm going to replace the thermo and flush the engine. The timing might still be off. Time for new thread.
Bryn

Bryn
Get a dwell meter. They are inexpensive and make a huge difference when setting points. The feeler guage method only gets you in the ballpark. Your car will run much better with the correct dwell. I wouldn't waste money on magnetic/optical/lazer beam/nuclear reactor/phaser gun trigger sets. With the miles we put on these cars points will last a long time. Just learn how to set them correctly. Anyone know where I could get lighter advance springs for the distributor? I saw some on the Cambridge Motorsports web but I am too cheap to pay for oversea shipping on them.
p Hazelfeldt

Bryn--Word to the wise: get the cooling in order before anything else. You may be in for an up-close-and-personal peek at the engine's bottom end if you don't. For the ultimate in protection, plan on having the rad recored for $200. or so.

Rick O.
Rick Orthen

The only time I've ever had a major overheat problem, (coupled with lack lustre performance) was in a Rally prep'd 1275cc Mini (a very long time ago!) We fought with it until somebody finally figured out the distributor mechanical advance was all messed up, it wouldn't advance properly at speed. Swapping out distributors solved both the issues at once. We still ran a stock rad and cooling system with no problems. I'd sure look carefully at the distributor and advance/retard systems in place.
Sid Turner

This thread was discussed between 07/07/2003 and 10/07/2003

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