Lucas PI Fuel vs Triple Webers

[jeremyrgunn]

Hey everyone, I have the stock carbs but i'm looking at what everyone is using on the TR6 motors now-a-days. I know the european cars came with the Lucas PI sys but seems to be difficult to find in the states and are supposedly tempermental. So i'm looking into ideas or should i just stick with the stock carbs and rebuild em?

Cheers!

-Jeremy

[jim3000s]

Have you considered fitting modern throttle bodies? Jenvey, or similar. These would be a direct replacement for triple Webers.

[Slow M]

jeremyrgunn said:

Hey everyone, I have the stock carbs but i'm looking at what everyone is using on the TR6 motors now-a-days. I know the european cars came with the Lucas PI sys but seems to be difficult to find in the states and are supposedly tempermental. So i'm looking into ideas or should i just stick with the stock carbs and rebuild em?

Cheers!

-Jeremy

As above, or:
Triple SUs, by Richard Good,
Six Mikuni single throat motorcycle carbs.

Also, there are a number of derivative designs, similar to Webers.
DellOrto, Solex, and SK all made their own version.

Also, you could do a single TB, on a shared plenum.

My top choice is Italian Webers.

What modifications have you made, or are you planning to make? What year is the car? Does your state have pollution testing?

Best,
B.

[Renaldo]

I have dual Mikuni carb conversion on my 2500M and they've been terrific.

Reliable, easy to tune, and more power.

Triples, no doubt would give you more oomph.

Ron

[RCK974X]

From direct experience, on 2500PI saloons, albeit a long time ago.

I wouldn't bother with a Lucas PI system, unless you get a complete one very cheap, with spares included.

In its day it was OK, but even then its reliability was suspect, and it needed tuning every 3 or 4 months, as wear of components was a problem, especially the parts which controlled fuel mixture. If you have the special tools you can adjust to a point, but it's still nowhere near reliability of carbs or a more modern EFi system.

The high pressure fuel pump for example, (approx 110 PSI) was simply a modified wiper motor with a different top, and frequently gave trouble. Nowadays you can swop it for a Bosch CIS (K injection) type pump which works a lot better.

I swopped all 3 of my PI saloons to carbs, even the ordinary 1 1/2" twin carbs aren't all that much worse for power, 1 3/4 were better, and there are various manifolds about, as above.

[madsvlund]

If you choose to go for modern EFI, do I have ignition and fuel map's for the 2500 engine, suited for VEMS ecu. And you can quite easyly convert the original SU's to EFI. I'll find the links later, but you can get an injector kit, that fit's inside the SU, so you keep the stock apperance but get the economy and drivability of EFI.

This TR6 was converted last year

[Slow M]

Mads, what's the copper pipe, under the fuel rail?

Best,
B.

[Mr Tiger]

Hi Jeremy,

Any chance you could post a pic of the compensator/linkage for the carbs please?

It's one original part I'm having difficulty sourcing and I'm not too sure how it all fits together.

I've got twin HS6 SUs with K&N filters on mine at the moment. Not running right yet but I live in hope.

Thanks,

Chris

[madsvlund]

Slow M said:

Mads, what's the copper pipe, under the fuel rail?

Best,
B.

That's for the heater and expansion tank circulation. It have later been replaced with a tube of stainless steel for the looks :-)

[jeremyrgunn]

Slow M said:

s above, or:
Triple SUs, by Richard Good,
Six Mikuni single throat motorcycle carbs.

Also, there are a number of derivative designs, similar to Webers.
DellOrto, Solex, and SK all made their own version.

Also, you could do a single TB, on a shared plenum.

My top choice is Italian Webers.

What modifications have you made, or are you planning to make? What year is the car? Does your state have pollution testing?

Best,
B.

I don't have to worry about pollution testing, the car is a '71 vixen. I have made 0 modifications thus far, planning for spring. However I'm looking to keep the car period specific with slight modifications such as EFI etc.

[jeremyrgunn]

madsvlund said:

If you choose to go for modern EFI, do I have ignition and fuel map's for the 2500 engine, suited for VEMS ecu. And you can quite easyly convert the original SU's to EFI. I'll find the links later, but you can get an injector kit, that fit's inside the SU, so you keep the stock apperance but get the economy and drivability of EFI.

This TR6 was converted last year

I would be very interested in the injector kit that fits inside the SU's that sounds about what I would like to see happen.

[jeremyrgunn]

Mr Tiger said:

Hi Jeremy,

Any chance you could post a pic of the compensator/linkage for the carbs please?

It's one original part I'm having difficulty sourcing and I'm not too sure how it all fits together.

I've got twin HS6 SUs with K&N filters on mine at the moment. Not running right yet but I live in hope.

Thanks,

Chris

I will take a picture when I get home tonight and post it up.

[madsvlund]

A few options for SU TBI conversion (throttle body injection)

http://www.pattonmachine.com/TBI-Components.htm#Ro... 4
http://www.pattonmachine.com/TBI-Pricing.htm

An option could be to skip the GM ECU and go for a megasquirt or VEMS instead, in case you want to be able to tune it you self. (I have TR6 MAPS for the VEMS)

Another option (not stock look)
http://www.extrudabody.com/servlet/the-319/Kit-cln...

http://www.borlainduction.com/2700-series.html