Welcome to our resource for MG Car Information.



TR parts and Triumph parts, TR bits, Triumph Car Spares and accessories are available for TR2, TR3, TR3A, TR4, TR4A, TR5, TR6, TR7, TR8, Spitfire and Stag and other TR models are available from British car spares and parts company LBCarCo.

Triumph TR6 - poor driveablity

This problem is more pronounced when the air temperature is cooler but do have the problem in summer:

From a standstill:
1.if I take off and let the clutch out (revs under 1000) and try to accelerate, the car hardly moves and is majorly sluggesh. If I floor the accelerator still nothing happens until I hit 2000rpm and then the car takes off.

2. If I feather the accelerator (quick rev) and then let out the clutch out from a stop the car is fine.

3. if I been driving and then come to slow traffic and the revs are between 1000-2000, and then need to accelerate I have a terrific lag until the engine comes up to speed over 2,000.

4. driving under 2000Rpm the car is very jerky and passengers don't want to ride with me and it feels like I just learned to drive standard...I can't drive it smoothly no matter how much money someone offers me!

HELP before I take a shotgun and blast the car

No shotgun needed...ya know you will get it solved here.
When driving for a while does it take time for RPM to drop when you come to a stop?
Check dash pot oil level? Also maybe because it is cold (the goose has left the building) your dash pot oil may be a little on the thick side causing a very slow response to the carbs. One carb may be reacting better than the other to throttle. With air filters off, push the air valve assembly up. It should drop kinda quick with a little "thump" as it bottoms out.

One thought for you.
Rick C
Rick Crawford

Hi Rick,

Answers to your questions

The RPM drop when I come to a stop after driving a while almost immediately.

The oil in the dashpots are Auto Transmission fluid so I don't think that the cold affects it as much.

Dashpot level is the recommendend 1/4" resistance when puting in the dipsticks

Hello Steve, you might wish to check your ignition system... particularly the advance in the distributor; it should have no lateral movement and only smooth radial movement. Also chek that the advance springs are in tact and havn't broke/stretched over the years. To much advance or an unsteady spark caused by a "floating" advance plate can be cause of your problems... an easy check and , if needed, fix. Additionally, examine the point block for excessive wear, dist. cap and rotor for arcing, HT leads for connections esp. from coil.
My two cents,
Cheers, Rob

Ps. why am I consistently listed as a non-member?... I've jumped the hoops and have a password, etc.
Rob Gibbs

Have you checked the carb diaphragms for holes?
Brent B

...remember, 90% of all "carburation problems" are in the ignition system :o)

I'm not so certain that statement applies to ZS carbs ,however!

Rob Gibbs

High performance cam, perhaps?

my cam is anything but high performance as is everything else in the motor!

Hi Steven,
Does the car start up ok when cold ? I'm assuming you don't have electronic ignition. First make sure your timing is you have good engine vac at idle ? pull the rubber line off that goes to the distributor and the engine idle should increase and you should feel suction the end of the hose.

If that is all ok then I'm sure the problem is in the carbs....
Does the RPM go up and down by itself at idle ?
Mixture too lean and timimg off will give poor performance when pulling away but "disappear" at higher speeds.
Assuming they are good and balanced...check for faulty bypass valves first then then the temp compensators
Hope that gets you going in the right direction
Charlie Ballard

I took off the vac line to the distributor long time ago because of irratic idle, I have a later car so there is no vac advance but rather vac retard which is only on for pollution controls. I have also removed the EGR valve and all the hardware for that as the car with the stuff on hit a wall at 4000RPM and struggled above that. No it free revs all the way to redline. Funny thing is I do not experience the hesitation when reving with clutch in but when the engine is under load when pulling away it is a pig until 2000rpm

The car starts up ok as long as I do not have too much choke and does sputter until it is warmed up or that I clear the engine by feathering the gas pedal.

I do not experience the hesitation when there is a bit of choke on so Charlie might have a point of the mixture being a bit too lean.

Re Timing, seems that the car only idles and drives ok when there is a fair bit of advance ~ 20 to 26 degrees which is way off the factory specs.

I do not have electronic ignition

Steven--20 to 26 degrees advance at idle??? That is a fair bit away from the 10 to 15 normally used. Perhaps the cam was not properly indexed when installed some time ago??? A couple of things to do:
--Replace your cap & rotor with the new spares you have in your boot (we all carry them, don't we?). I have had the worst luck with caps/rotors that generate similar symptoms (runs crappy off-idle, great at speed).
--Check ignition cables for cracks etc.
--Shoot throttle shaft bushing areas with gumout to find vac leaks.

Rick O.
Rick Orthen

Hi Steven,
It sounds like your timing is way off and trying to compensating for another problem. I would go thru' all the basics...check all wires,rotor,cap reset points, the best way is with a dwell meter if you can borrow one ? Check the colour of the plugs, measure engine vac (about 17 and the needle should be steady )
I think the dist should be backed off and reset your idle at the carbs and re-balance them. I have a 75 like you and I've been thru' the same type of thing, but now I have it running'll get there !
Charlie Ballard

A quick way to check if timing is your problem: simply loosen the distributor collar and experiment with rotating the dist. in either direction a small amount. Keep the collar tight enought so that it can be moved by hand but yet is not loose enough to move by itself- that way you can drive the car around after making the adjustments -and can continue to adjust without having to keep wrenching it! When timing is right lock it down.No special tools or experience needed. Timing is right when it runs best!

just to let everyone know

the car has new wires, cap and rotor, as with points.

Gaps are right, the cam has never been replaced and the engine has 55,000 original miles.

Carb has been rebuilt and has all new bushings and seals around the shafts.

As far as plugs go they tend to be a bit black (carbon) however the 2 middle plugs tend to be white.

Regarding timing, I used a light and when set to specs the car runs like crap. I basically do what Michael suggests and move it until it runs best. When I checked it after thats how I find that it is over 20degrees.

This hesitation under load from 800-2000 is especially noticeable when the outside temp is colder but do have this problem in the summer. One thing I noticed this past weekend when it was around 0*C that when I try to take off (without reving) and the car struggles I give it more gas, the car momentarly cuts out, makes a pop sound coming from the carbs and then the car takes off.

All other driving speeds the car runs beautifully with lots of pep and power and on a run on the highway from Toronto to Kitchener to put the car in storage I averaged 35MPG.


Wow, 35 miles to the gallon. You must be lean.

Tom might have hit the nail on the head. 35MPG...WOW!
Also, are the 2 carbs synchronized?
Rick C
Rick Crawford

When I first got Grumpy (74 1/2) I could not get off the line without major stumbles like you describe ... backfiring through the carb, missing and then finally away we go. Once warmed up .. no problem ...hence the nickname Grumpy.

The single thing that I did that fixed the problem ... oil in the carb dashpots. Now all it takes is a little choke to get it running and a little less and less to keep it running smoothly as it warms up.

Next spring when you get it out of storage, check out the dashpots, diaphrams and also check all the associated vacuum hoses etc for the pollution control.

Bring on spring!
Sid Turner

Hi Steven,
The weather is way to nice to put it away !! I'm still driving mine..a bit chilly ( top down ! )in the morning going to work but really nice going home.
If your car is in Kitchener ( so am I )and you want to look at it in the near future I'd be happy to stop by and offer what I can .
Charlie Ballard '75 TR6

If I were running 35 mpg lean, I'd be looking to replace the burned exhaust valves.

Rick O.
Rick Orthen

Stop driving under 2000rpm! Sorry, couldn't resist:-)

I own a 71 TR6 in need of major frame restoration. I have the car pretty well down to a rolling chasis and need advice if anyone knows of a qualified frame and chasis shop in Minnesota or somewhere close. I would appreciate any input someone may have.

The body came off fairly easily. I just drum my fingers on the bonnet/(hood) in frustration-then swept it up off the floor!

Thanks for any help you can offer.
Dan Huebert

This thread was discussed between 14/11/2004 and 21/12/2004

Triumph TR6 index