TR6 Excess Fuel Lever (ELF)

[70tr6pi]

Hello,

I own a beautiful 1970 TR6 pi that I recently purchased . Car runs and drives beautifully. problem that I have is that there is no one here in the USA who knows anything about the pi system. You ask, why did I purchased it? Well after driving the US none pi models and then driving this one, it was like day and night. I dont care how many carbs one hangs from the side of the engine.

 

Person I purchased the car from, had the metering system checked and (I guess) refurbished 4 years ago by Prestige (Mr. Malcolm Jones). A while ago, choke cable to the EFL broke and I ordered a new one from England (Moss).

 

Will someone answer the following questions please?

1. When pulling on the choke cable (during cold start), how far back the EFL should be pulled back, when the choke cable is fully engaged/pulled back? ¼, ½, ¾, or all the way back.

2. How should the EFL be adjusted with respect to the Cold Start Cam (CSC)?

3. Should the CSC to be engaged, while the EFL is completely off before the choke lever is fully depressed, or should they move in unison?

4. To set the Ideal properly, per Bentley repair manual, adjusting the throttle body valves (butterflies) gap to 0.002 in (0.05 mm). However, I was told to set the ideal, set the gap to zero (0) and than adjust the ideal by turning Air Valve.

5. How often does one need to adjust, repair, etc the metering unit?

 

Thank you all for your help. I appreciate any additional pointers that any of you may have.

 

Sincerely,

 

Sam

[Peter Cobbold]

Sam,

Welcome to the forum and Lucas' PI.

There is a short answer that many of us used when our cars were daily drivers: disconnect the cable that operates the buttefflies.Starting procedure from cold was: pull on the excess fuel (choke), blip the throttle a few times, push the efl home and drive off, being ready to pull the efl and blip if the engine stumbled.

 

In ten years and ca 250k miles the MU never gave problems. Butt that was daily driving and no ethanol fuel. Nowadays there are several specialists to turn to. In 1978 even Lucas had lost interest, but it never went wrong. Just as well......no forum back then.

I would try to avoid fuels with more than 5% ethanol the max allowed in UK. And if you plan to leave the engine unused for months add an inhibitor to the fuel and run it through the MU upon lay-up.I no longer run PI so am not familiar with the best brand of fuel dope,

 

Peter

Edited September 10, 2017 by Peter Cobbold

[aardvark]

Hello Sam - good choice with the CP TR6

 

Answers to your questions;

 

1. Should pull back fully. Choke amount depends on where you live (how cold). My car needs full choke only to fire up then push in half way. Push choke in as soon as possible otherwise it will flood.

 

2. My car has the throttle body cam disconnected. I adjust the throttle via my foot! Technique is exactly how Peter explained. BTW the twin choke cables are horrendously expensive £80 ish whereas a single choke cable is around £10 if I remember rightly!

 

3. I'd disconnect it. You only really need the EFL connected to the choke cable.

 

4. Yep gap to zero and set the idle via the air valve. The TR5 needed the throttle valves gapping because it didn't have an air valve.

 

5. Once the MU is set up then it shouldn't need adjusting at all. They were supremely well manufactured. Don't be tempted to mess about with the springs unless you know what you are doing either!

 

Have fun - its a great car!

 

Cheers

Dave

[70tr6pi]

Gentlemen, thank you. I will readjust my cable to the EFL.

 

How is the mixture controled and adjusted? Is that something that is set and adjusted on the MU and I should avoid messing with it, or can I adjust the mixture my self (a novice do it at home mechanic)?

 

How would I know if my car is running rich or lean? Besides checking the plugs and the tail pipe.

 

How may I compensate for altitude?

 

Once again, thank you very much.

 

Sam

[Mike C]

Personally I leave the MU mixture/manifold pressure adjustments to an expert with the correct test bench/tools/spare part selection. If you want further info on the Lucas PI system Vitessesteve has it collected on his webpage here:

 

http://vitessesteve.co.uk/LucasStuff/Lucas_Petrol_Injection_Manuals.htm

[Peter Cobbold]

Sam,

Best way to monitor mixture is a wideband AFR meter - the UEGO sensor goes in the exhaust. Several suppliers eg AEM , about $150.

Read the meter as you drive.

 

 

Metering Unit can be adjusted with that AFR information, others have done it, eg TimD. However do not try to lean the cruise mixture. It has to be set rich to avoid pinking upon flooring the throttle because there's no throttle pump:

https://supertrarged.wordpress.com/2013/06/12/the-lucas-pi-lean-spike/

 

There were long threads a few years back about altitude compensation. There's no off the shelf answer as far as I recall.

http://www.tr-register.co.uk/forums/index.php?/topic/5680-altitude-adjustment/

http://www.tr-register.co.uk/forums/index.php?/topic/31042-pi-versus-altitude/

http://www.tr-register.co.uk/forums/index.php?/topic/51621-pi-metering-unit/

 

Peter

Edited September 11, 2017 by Peter Cobbold

[Tim D.]

Thanks Peter... Yes with an AFR meter you can easily get the MU spot on. My AFR has been one of the most useful tools I have ever built. You can see real time on real roads where your mixture is and then how it changes when you make an adjustment.

Cheers

Tim

[cp25616]

Sam, the cold start cam is there for a purpose and that is to sustain and adjust the revs when starting from cold. Yes by all means wire up the excess fuel lever on the metering unit but make sure the second part of the cable operates the cold start cam. You don't want to be continually playing "lets keep the revs up" by sitting in your TR with your foot on the throttle when the garage door needs shutting or you have to run back into your house for something forgotten. Its a relatively easy task to synchronise the cold start cam to just open enough for say 1500 to 2000 revs at cold start up and upon pushing in the "choke control" knob after warming then the cold start cam comes off cam and normal tick over revs will be the order of the day.

Remember, and I am not saying this is the case with the ones that have answered above, some people don't have the correct twin cable anyway or its too short (later version) or its broken which does not allow them to wire up the cold start cam anyway thus making do with just the enriching lever on the MU only........ this is not ideal.

If you have the twin cable and its long enough for both functions then please utilise both as you will find it easier to start from cold and keep running at least.

Alan G

[70tr6pi]

I own a beautiful 1970 TR6 pi that I recently purchased . Car runs and drives beautifully. problem that I have is that there is no one here in the USA who knows anything about the pi system. You ask, why did I purchased it? Well after driving the US none pi models and then driving this one, it was like day and night. I dont care how many carbs one hangs from the side of the engine.

 

Person I purchased the car from, had the metering system checked and (I guess) refurbished 4 years ago by Prestige (Mr. Malcolm Jones). A while ago, choke cable to the EFL broke and I ordered a new one from England (Moss).

 

Will some answer the following questions please?

1. When pulling on the choke cable (during cold start), how far back the EFL should be pulled back, when the choke cable is fully engaged/pulled back? ¼, ½, ¾, or all the way back.

2. How should the EFL be adjusted with respect to the Cold Start Cam (CSC)?

3. Should the CSC to be engaged, while the EFL is completely off before the choke lever is fully depressed, or should they move in unison?

4. To set the Ideal properly, per Bentley repair manual, adjusting the throttle body valves (butterflies) gap to 0.002 in (0.05 mm). However, I was told to set the ideal, set the gap to zero (0) and than adjust the ideal by turning Air Valve.

5. How often does one need to adjust, repair, etc the metering unit?

 

Thank you all for your help. I appreciate any additional pointers that any of you may have.

 

 

Gentlemen, thank you. I will readjust my cable to the EFL.

 

What about the mixture control? Is that something that is set and adjust and I should avoid messing with it, or can I adjust the mixture (a novice do it at home mechanic)?

 

How would I know if my car is running rich or lean? Besides checking the plugs and the tail pipe.

 

How may I compensate for altitude.

 

Once again, thank you very much.

 

Sam

 

 

 

 

 

 

 

Once again THANK YOU all for taking time to answer my questions.

 

I bought my choke cable from Moss UK (PN: 214888). Do you gentlemen prefer another parts distributer?

 

Cheers,

 

Sam

[70tr6pi]

PLEASE READ ONLY THE BOTTOM PORTION OF MY LAST POST.

 

SORRY.

 

THANKS AGAIN,

 

Sam

[peejay4A]

Sam, the cold start cam is there for a purpose and that is to sustain and adjust the revs when starting from cold. Yes by all means wire up the excess fuel lever on the metering unit but make sure the second part of the cable operates the cold start cam. You don't want to be continually playing "lets keep the revs up" by sitting in your TR with your foot on the throttle when the garage door needs shutting or you have to run back into your house for something forgotten. Its a relatively easy task to synchronise the cold start cam to just open enough for say 1500 to 2000 revs at cold start up and upon pushing in the "choke control" knob after warming then the cold start cam comes off cam and normal tick over revs will be the order of the day.

Remember, and I am not saying this is the case with the ones that have answered above, some people don't have the correct twin cable anyway or its too short (later version) or its broken which does not allow them to wire up the cold start cam anyway thus making do with just the enriching lever on the MU only........ this is not ideal.

If you have the twin cable and its long enough for both functions then please utilise both as you will find it easier to start from cold and keep running at least.

Alan G

+++1. Trying to keep it running when cold just using the throttle is a recipe for a shunt. Others will disagree.

[aardvark]

+1 disagree. My car is off choke completely within around 2 mins. That's the time it takes to shut the garage, put seat belt on and drive to the end of my relatively short road. Our cars are all different and my experience is only with my car. If I found it dodgey in any way I would not do it.

[Steves_TR6]

Everyone has their own opinion , here's mine

 

Neither of my two tr6's had the 'fast idle' part of the choke cable connected.

 

Both were different but started and ran fine and were completely off choke within 3-5 mins.

 

I am about to experiment with an electronic idle conrol, based on a solenoid air valve, that will increase idle when cold and maybe remove the need to use throttle for those 3-5 mins.... ( and also help with idle when the engine is really hot in traffic and cyls 5/6 dont ge enough air) will report in with progress!

 

Steve

[Rem18]

I live and drive in the alps.

Previously ran a rich MU on idle on my tr5 (it had tr6 springs) it was impossible with constant stalling over 2,000m

With that I constantly cranked the mixture in and out as I went up and down just like I do with the distributor wheel.

You can do it without a meter and use the seat of your pants, but you do need to feel confident.

Always make a note of what you do, so you can get back to where you were.

Remember also it's exponential on the screw.

Lastly it's all rather irrelevant if your vacuum isn't set up right so you need to know your compression too. Also you should monitor the fuel pressure as well, possibly this and the vacum while driving...

I have the choke cam off.

In the end if you are having fun and getting reasonable fuel economy just enjoy!

T

Edited September 13, 2017 by Rem18

[70tr6pi]

Thank you all for your help and comments.

 

Cheers,

 

Sam