MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

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 - Cr on a 1971?

Is is going to be 8.6:1 as the head numbers suggest an early carb tr6 (it's a new block and in the wrong car so chassis number is a bit irrelevant!

Alastair

PS. what is the point of vacuum retard? How does it improve emissions?
aj mcmurray

I wrote that very poorly, please accept my appologies :-)

Alastair
aj mcmurray

Alastair, I hope that your first thread is not an example of they way they speak the Queen's English over there! (and they think that us North American's butcher the language!!).

Answer to your question is: vacuum retard is a way of improving emissions but over time it becomes more of a nuisance and causes lumpy idle. I removed mine and never looked back in addition of taking off the EGR crap. Now in other parts of the world you may not get away with it as your car might have to be emission tested to be licenced for the road. Here in Toronto cars prior to 1978 are exempt.

Regarding compression ratios this is the progression:

8.5:1 1969-1971; 7.75:1 1972-1973; 7.5:1 1974-1976
steven

Hi Steven
Did you simply disconnect your vacuum retard and plug the hole at the carb and dist. or was there more to it ? I drive a 75.
Thx
Charlie
Charlie

Charlie
Consider using a small round rod or anything that fits inside the pipe and plug both ends. This allows u to plug it but keep the pipe in place for originallity.
I do not have EGR
Rick C
Rick Crawford

Im glad to hear a good reason to disconect my vac. line, but what about the centrifical weights in the distributor?
Mike Smith

Mike,
Are you asking if the weights can be removed/disabled, like the vacuum retard?
My answer is NO! They advance the ignition as the revs rise, to respond to the shorter time that the piston spends at the top of the compression stroke. The flame front of burning fuel travels at a relatively constant speed, so at higher revs it must be initiated earlier to provide the "oomph" at the right time to push the piston back down again effectively. The precise shape of the advance curve with revs is a function of the mass and shape of the weights and their retaining springs, and is an ever-popular discussion point among performance freaks.

John
JohnD

All,
Sorry, I meant to add:
If you do disable your vacuum retard system, make sure that the contact breaker carrier is securely fixed to the baseplate. Otherwise it will flop about and make ignition timing more random than ever. A screw through to the base will suffice.
John
JohnD

If you disconnect the vacuum advance capsule, don't forget to set the static timing to approx 10-12 degrees BTDC before determining the optimum setting.
The device was used to advance ignition timing when throttle is closed ( eg on over run, or tickover ) to give the weak mixture longer to burn. UK engines never used it.
Peter Cobbold

This thread was discussed between 12/08/2002 and 25/08/2002

Triumph TR6 index