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Triumph TR6 - Factory PI system conversion.....good or bad idea

Just bought a complete factory PI system that was rebuilt. Any pitfalls on doing the swap or is it a bad idea.
Yeahbaby

Heybaby.....

If you have a standard US spec engine (carbies), just converting the fuel system is a waste of time and money. The UK PI motor differs in many respects, notably the head design, compression ratio and cam.

If the engine is up to spec, you should consider the maintenance and tunig problems you may encounter. Some aspects of the Lucas PI system require very specialised knowledge and equipment to set-up and maintain. Unless that support structure is close by, you would be much better off going for an electronic PI system rather than the mechanical Lucas one.

Regards
Roger
[73 LHD Nevada car converted to RHD Lucas PI - 125 BHP ATW]
Roger H

I will agree with what Roger has said that just bolting on the PI system is not going to give you gobs and gobs of power with out doing some homework first. You need the right head to begin with, the port spacing needs to be correct for the PI throttle bodies to bolt up to. The TR5 and early TR6 cam was alot more radical than stock, but you can easily add an aftermarket cam that will give you what you need. Back to the head, easy enough to have it shaved to bump up the C.R.
All parts of the PI system are easy enough to rebuild ( except maybe the metering unit, but it is easy enough to take apart, change seals etc)
As Roger had mentioned you do need some pretty special equipment ( like a flow bench ) to properly calibrate a metering unit, but if yours has allready been done, you should be good to go. Personally, I like the Lucas system over an electronic one.............purely mechanical...........no stray electrons causing you grief............the rest of the cars electrical system does a good job of that!.
Anyways, i say go for it................and if not, hey, im always in the market for PI spares from my TR250/PI

cheers,

Mitch
Mitch Smith

If you want it to look sort of original the stock unit is ok. If you really want it to go there are many better options.

How about this one?
(with thanks for Alan A.)
DON KELLY

Lucas fuel injection is generally a reliable, simple mechanical system. It was designed for power, not economy and was also used in Brabham racing cars and Maserati (at LeMans).

The achille's heel for use in a production car has always been the need for specialised equipment and knowledge.

It gained a reputation for being unreliable mainly due to 'bush' mechanics tampering with it in an effort to fix something that may be unrelated to the system itself.

Known issues are:

Lucas fuel pump cavitating under high temperature conditions (car stops with little warning - vapour lock in fuel line)

Reduced fuel pressure - poor performance due to inadequate voltage at pump (fixable with direct uprated wire feed via relay).

Hot start problems, usually injector or injector pipe related.

Running rough, usually inlet manifold butterfly synchronisation and/or injector blockage (dirt), 'O'ring seal deterioration or injector blow-off pressures not synchronised or to spec.

If, and I mean IF, the metering unit is properly reconditioned you will most likely not need to touch it. MU shuttle tolerances are important and cannot be adjusted or fixed other than by swapping around different parts from a variety of units. They wear over time and some of the units have had a hard life. I had my unit reconditioned (had to send it out of State and cost well over $1000) and it was great until the engine block got hot. Thermal expansion caused the shuttle to sieze, shearing the plastic distributor drive dog.
I sent the unit back and another shuttle was found (5thou less in diameter) and it has be faultless since.

Bear in mind also there were several Triumphs that had Lucas PI including saloons and 2 litre engines. Each metering unit is different for each model and the colour of the springs in the top of the MU is one way to tell - but it is not definitive. The 150 BHP UK metering unit had RED springs. There were also blue springs used (CR models) and a range of black springs (saloons). The springs control the progression rate of the fuel flow under light load, accelleration and full load, so they are closely linked to performance and the MU should be matched to the cam and distributor for maximum benefit.

Other things to consider are: modifications to the fuel lines and tank (you need a swirl pot or internal baffles or the fuel flow to the pump can be interrupted on left-hand bends when there is less than 1/4 of a tank of fuel); a correctly profiled distributor (virtually impossible to get an original TR5/early TR6); modification of electrics (inertia cut-off switch) and pump feed/relay; new choke and accellerator cable.

The minimum equipment you need access to is a fuel pressure gauge with in-line adapter and a throttle-body air-flow synchro tool.

If you are experienced in things mechanical, then give it a shot, particularly if you have some local backup - the more of them on the road the better.

Cheers
Roger

Roger H

OOPs forgot to paste
http://i123.photobucket.com/albums/o316/donkelly23/ALANASPIManafold.jpg
DON KELLY

That looks pretty slick Don...... (and I can forgive the Triumph logo being from the motorcycle!) I'm only guessing at BMW airflow metering with custom manifolds and bosch injectors????

Is there anyway of getting more details on this?
Roger H

I would love to get credit for that. It is owned by a New Yorker who had it custom built for his PI modification. I have a better photo somewhere in cyber computer. He has just recently fired it up and now has some computer dialing in to do.
Yeababy has already gotten feedback from him on another site.
DON KELLY

A long while ago, I remember a guy named "Tony Gordon" did the conversion from carbs to PI. He wrote a detailed article on the bits needed to do it. Here is the website: http://www.thelittlemacshop.com/trsite/download.html

Berry Price
BTP Price

Berry Price,

Im not having any luck with that link...........does it work for anyone else?
Mitch Smith

Sorry Mitch try this: www.triumphowners.com/resources.cgi?parentID=111424

Click on the "PI conversion notes on the left side. There is a lot of other PI stuff too.
Berry Price
BTP Price

Good stuff, thanks Berry!
Mitch Smith

Mitch - if you don't have this resource already, check out the attached TR6 forum link for hundred of references to sorting the Lucas PI


http://www.tr-register.co.uk/forums/index.php?showforum=7
Roger H

Thanks Roger,
I have been a member of that forum for the past 2 years, and it is a wealth of PI info!

cheers,

Mitch
Mitch Smith

I have been watching this guy move forward with interesting EFI (and supercharging) projects for about 3 years now. Seems a VERY good system.
Gene

Oops! Forgot to post the link!
http://www.sidedrafttbi.com/
Gene

This thread was discussed between 03/04/2007 and 19/04/2007

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