View Full Version : TR6 TR6 Sputtering

08-11-2003, 02:19 AM
I've been struggling with a problem with my 76 TR6. It has developed a sputtering when warmed up and not under heavy acceleration. I would call it hesitation but it has gone far beyond that now. New points, plugs, spark plus wires, coil, air filters, ... I haven't attacked the carbs, yet, as I don't know if I will cause more problems than I'll correct.

In trying to correct, additional questions have surfaced as to the timing and the plug wires. Setting the static at 10' BTDC gives an idling dynamic timing of 2' ATDC, instead of the desired 4' btdc. Is there some adjustment I am missing? Which should I use?

And one last oddity. The #1 cylinder(front) spark plug wire attatches to the innermost post of the distributor - nearest the engine. Bentley's and TRF's diagrams show the #1 attatching to the outside forward post. Is it possible to have the plug wires off 180' on the distributor and still have the car run?

Any help would be appreciated

08-11-2003, 03:47 AM
Hello Trevs,

I presume you are checking the dynamic setting with a strobe?. Does it have a timing advance knob on it, which is not set correctly?. Normally you would expect the timing figure at idle to be larger than the static, i.e. more degrees before TDC as it will advance from very low revs, more so if you have not disconnected the vacuum line to the distributor. You could try and check your timing at 3,000 rpm, my UK spec PI engine has a static of 8 plus a total advance of 28 giving a 36 degree BTDC setting. Don't be afraid to try different than book settings until you find what suits your engine, especially as the fuel nowadays is not the same as when Triumph built the car.
Regarding the plug wires, yes it is quite possible to put the distributor in a 'non standard' position, the engine couldn't care less if the timing and order is correct.

good luck,

Alec graemlins/cheers.gif

[ 08-11-2003: Message edited by: piman ]</p>

08-12-2003, 02:17 AM
The timing is being checked with a strobe which does not have the adjustment ability. I did try to vary the timing by+/- 6 to 8 degrees with minimal impact. The roughness (which is extreme, close to making the car undriveable) remains.

This condition only is present once the car has reached operating temperature. Keeping some choke on does not cure it for the warmed engine, if that gives someone any more clues.

Am I looking at carburettor ails? This car has the dual strombergs.

08-12-2003, 04:51 AM
Hello Trevs,
sticking with the timing, the distributor should not retard the timing, which is what you have if static gives 10 BTDC and stobing gives 2 ATDC, what does the timing do if you rev the engine, it should go further advanced.
My only thought, and I honestly don't know if this could happen, is that a distribtor has been fitted that rotates opposite to what the TR engine should have. The vacuum plate would certainly retard the engine, but I don't know about the mechanical advance. If the engine ran correctly before then this can't be what the problem is.
Could you be mixing up your befores and afters?.
Looking from the front of the car, any before mark will be to the right of the TDC mark on the damper.
The other suggestion is to check the colour of the plugs, to get a clue on mixture.

Alec graemlins/cheers.gif

[ 08-12-2003: Message edited by: piman ]</p>

08-12-2003, 02:12 PM
The specs I have for teh car shows a static of 10 degrees btdc yielding a dynamic of 4 degrees. These values come from both the owners manual and a sheet out of moss motors web site. If the rotation was wrong, I'm sure all **** would be breaking out, as I do have the plug order correct (or at least as spec'd.

I am referring to btdc as to the right when facing the car. This would be to the distributor side as opposed to the carburettor side. When removing the vacuum hose from the distributor, the timing goes further retarded by about 4 degrees and the rpms rise to about 1200.

08-13-2003, 02:53 AM

Thanks for your input. That setting sure seems far off from the specs, but if it works, who cares.

I'll try that, then wait for the back-ordered distributor cap before going on to the carbs. The part has been back-ordered from TRF for a month. Seems like a pretty standard part to not stock, but it also seems that TRF has been less than relioable on much of the items I've ordered recently. I hope this does not mean they are getting out of the business.

Gary Pope
08-13-2003, 03:30 AM

When you take the vacuum pipe off the revs will go up, because it's sucking in too much air. The advance plate in the distributer will not be sucked back anymore an so will return to its resting position. I believe most people just keep the vacuum pipe off and plugged and set the timing somewhere between 12 & 20 BTDC. You will have to experiment to see what works for your car.

I also wanted to point out that because the No1 plug pole on the distributer is one more off than
the book picture, suggests that the distributor is used to being advanced further. The vacuum unit would hit into the cylinder head if you try to advance it with the poles in the position of the book.

Rob DeScherer
08-13-2003, 10:18 AM
You should be able to get a distributor cap at any good auto parts store. There is no need to wait for TRF. Try NAPA or Pep Boys. They may not have the Bosch part, but they will be able to get you a good, aftermarket part that will match exactly. Both places have been able to get the cap for my 74 TR6.

08-13-2003, 11:33 PM
Given that your initial question was about sputtering have you made any inroads to fixing that?

I doubt that your timing setting would produce the sputtering fault - so see most of these responses as side issues.

I once had many bizzare faltering problems at anything over 4K RPM and tried replacing so many things - to in the end find that it was a faulty condensor in the distributor.

Problems that only show themselves when hot could still be electrical. I've heard of coils, condesors and even plugs that fail when at certain temperatures but work at others. But it looks like you've replaced most things.

You need to try and observe what else is happening when the problem occurs.

When its warm why not try holding the throttle open to maintain revs at the dodgy point (if there is a worse point) and then wander around the engine looking for things to fiddle with. Like removing plug leads and replacing one at a time to see if something ignition based is failing on one cylinder.

What about fuel delivery issues when warm v's cold? Has there been a change anywhere in fuel lines that may have caused vapour lock to occur when hot?

It sounds like a mixture thing to me.

If something was rich all the time it would start great when cold - and seem to run fairly easily even with the choke pushed back in early. I imagine under heavy acceleration a rich condition would also not show any problems.

But if it were too rich it would idle like a bitch - cruise like a bitch and probably idle too high.

What colour are the plugs?

I don't know enough about the stromberg's to comment on what to do with them. But if you had SU's I'd say that your jet height was a problem or that a needle was sticking when hot.

I'd go back to basics on the carbs and do a full reconfig as per the manual.

08-14-2003, 01:39 PM

I believe this sputtering problem has always been a known trait of the TR6, and I can remember going through all of this with mine a few years back. After an assortment of replacements and tweaks, I never did completely get rid of the problem. Some days it was worse than others, in fact some days it wouldn't do it at all. I do know that when I would pull the choke out slightly (after fully warmed up), it would help.....but then other days it wouldn't make any difference. Talk about temperamental!!


08-14-2003, 02:45 PM
I had a sputtering problem with my 74TR6. It occurred from 1k to 2.5K RPM. I tried all the things you have tried. It ended up being the distributor itself, specificly the distributor shaft. There was a slight undetected wobble that caused the misfiring. Replacing the distributor with a spare provided by a friend cured the problem. Might be worth a try.
I have also disconnected the vacuum retard and plugged the carb. The retard feature has no performance factors, just emissions issues.

Carmine graemlins/driving.gif

08-15-2003, 02:26 AM
Thanks for all the help guys.

I went through the ignition all over from scratch, and found the garage where I had them put in the points and set the timing had gapped the points way too spread. I didn't measure, but it had to be closer to 0.030. Tightened that and all is good with the world.

Every once in a while I need to get dope slapped to remind me why I work on the TR on my own rather than letting the local garage screw it up.

08-16-2003, 05:47 PM
I will repeat something that I had posted a few days ago about a poorly running TR6, ALWAYS set your points with a dwell meter.