Metering Unit

[jemgee]

I have not had to touch the PI system since I bought the car in 2003. According to the bills from a previous owner one injector was replaced in 1998 so I guess the whole system has done very well. Over the weekend I have expereinced a problem on no 4 cylinder with a very weak pulse so I have decided to replace the injectors and feed pipes completely from Prestige.

 

As the MU is of indeterminate age I might as well bite the bullet but I am now faced with the choice of which Prestige unit £154.95 or the upgraded one at £277

 

Does anyone have any advice as to which to go for?

[Dave Worne]

Hi Jemgee.

 

If you look back, you'll see many references on the forum. I've used 'Katie Raven-Smith' in the past for a rebuilt M.U.

 

You can e-mail k_raven_smith@yahoo.co.uk.

 

I have no tie up with the above, I was satisfied with what I had for the cost.

 

 

Dave

 

 

Now with the 4A & the 6 (wifes) both on the road.

[Les Pettitt]

Hi Jemgee,

I went for the upgraded one on the basis I will keep the car until too old to drive and then pass it on to one of my sons. My MPG immediately improved from around 20-22 to 27-28 mpg on fitment of new MU. Only downside I can report is that the new MU makes a mechanical clack, clack noise but this in only really noticable with the hood up.

Regards

Les

[Jersey Royal]

Hi Jemgee,

I went for the upgraded one on the basis I will keep the car until too old to drive and then pass it on to one of my sons. My MPG immediately improved from around 20-22 to 27-28 mpg on fitment of new MU. Only downside I can report is that the new MU makes a mechanical clack, clack noise but this in only really noticable with the hood up.

Regards

Les

 

 

Les,

 

As a matter of interestwhat is the difference between the two MU, apart from the cost?

 

What causes the mechanical clack noise?

 

Regards

Guy

[jemgee]

The rotor inside the upgraded unit is brand new remanufactured to Malcolm's design - the base unit reuses an original which will have some wear on it. Details are on his web site

[jonlar]

http://www.prestigeinjection.net/metering%20Unit2.htm

[Jersey Royal]

The rotor inside the upgraded unit is brand new remanufactured to Malcolm's design - the base unit reuses an original which will have some wear on it. Details are on his web site

 

 

I see so the upgraded one has special seals and remanufactured rotor.

 

What about the clack clack, is that optional ?

 

All for an additional hundred odd quid.

 

Not being funny but surely something cant be right with Les new unit.

 

Regards

 

Guy

Edited May 10, 2007 by Jersey Royal

[Phil Kirk]

I went for the upgraded unit and I am very pleased with it. Must admit I have not heard the clack clack sound...maybe because of the sports exhaust I fitted!!

Phil.

[Les Pettitt]

Hi Guy,

I spent the day with Malcolm when he fitted a new Bosch pump, new MU, new injectors and he worked on my prv. I didn't notice the noise when he took it out for a series of test drives but only when I went to drive home (at a sedate pace compared to the second gear outings at high revs with Malcolm while he was trying to cure a resonance problem). I was so bothered about the noise I turned around after a couple of miles and went back to Malcolm's house. He came out and listened and didn't think there was a problem. I can only say it has worked perfectly the last few years but it does make a knocking noise that was not present in the original one. Unfortunately I don't do a high mileage so can't say whether it decreases with time and wear as I have probably only covered 1500 miles since it was installed.

Regards

Les

[Jersey Royal]

Hi Guy,

I spent the day with Malcolm when he fitted a new Bosch pump, new MU, new injectors and he worked on my prv. I didn't notice the noise when he took it out for a series of test drives but only when I went to drive home (at a sedate pace compared to the second gear outings at high revs with Malcolm while he was trying to cure a resonance problem). I was so bothered about the noise I turned around after a couple of miles and went back to Malcolm's house. He came out and listened and didn't think there was a problem. I can only say it has worked perfectly the last few years but it does make a knocking noise that was not present in the original one. Unfortunately I don't do a high mileage so can't say whether it decreases with time and wear as I have probably only covered 1500 miles since it was installed.

Regards

Les

 

 

Hi Les,

 

Strange thing is my MU has recently started making the same noise, i would describe as a ticking noise. Doesnt bother me at present as can only hear it at tick over. I have replaced the MU on my car some while back , cant recall who the supplier was as i didnt fit it.

 

I have spoken with Gary at TRGB and he says some do that after a while , but is not a concern. I also do not do a great mileage in the car on an annual basis, so untill some one tells me i have a problem, its staying as is.

 

Regards

 

Guy

Edited May 10, 2007 by Jersey Royal

[Andy Moltu]

I gather most of the TR traders get their bits from KMI & some from Prestige I think.

There are only few specialists who do Lucas injection stuff these days - which has essentialy left the market to the two above as far as metering units are concerned.

 

As has already been mentioned in this thead there are a few small suppliers like K Raven-Smith who seem to supply far cheaper than the others. A higher price doesn't always equate to higher quality.

 

Seemingly all of the TR parts suppliers do their "own Bosch pump" kits however Bosch only do a limited range of pumps that are suitable & essentially make a big mark up on a cheap pump, filter & hose fittings. Whilst this may seem to be going off the point it illustrates an example of a collection of bits that you or I could buy for less than £150 from Bosch dealers & hose assemblers that suddenly acquires a £300 price tag when the words TR, classic & car are put together.

 

Lots of testiculation is tied in with the alledgedly complex Lucas PI system which makes it untouchable for us mere mortals!

[Richard Crawley]

I believe the uprated M/U also uses a rotor/shuttle made from self lubricating steel to counteract the very low lubrication properties of unleaded fuel. I bulked at the large price difference for an uprated M/U & run a Prestige standard unit which, apart from an initial problem, has worked fine for 3 years now. The rattle you can hear (almost like a diesel engine) is made by the shuttle; some units seem to make more noise then others & are usually more noisy as the revs die down after blipping the throttle or when the motor is on a trailing throttle but it’s not a problem.

 

The Lucas PI system is far from complex & is actually very simple but you do need to fully understand the principles & the effects of what you’re doing before you start fiddling with it. Twiddling by misguided Sunday afternoon mechanics more used to carbs was the main reason it got such a bad name when first introduced on TR’s in the late 60’s.

[Andy Moltu]

The low lubricity of unleaded fuel doesn't seem to have been a problem in practice. In the early days of unleaded fuel there were concerns about it's effect on old fuel systems however much of the early problems were doen to the formulation of unleaded petrol rather than the absence of lead per se. (The lead was a cheap way of boosting octane & also protected soft exhaust valve seats but probably didn't lubricate much elsewhere) Early unleaded juice had a lot of benzene & other volatile elements which dissolved some seals & pipework as well as perhaps having an effect on mechanical wear.

 

I gather modern unleaded fuel contains less benzene than leaded 4 or 5 star fuel did.

 

The most convincing arguament for the new rotor is if the old one is worn beyond reasonable adjustment in the reconditioning process. In the end adjustment, seals & springs won't compensate for excess wear.

[JohnC]

self lubricating steel

Hi Richard,

Never heard of this, but I'd love to learn more. Do you have any info? Based on many letters and some articles over the years in TR Action from Dr MS Bingley, I'd assumed that lubricity issues were (ahem ) b-s. I've only done relatively few (trouble-free) miles on my PI unit with unleaded-compatible seals, but I've seen no ill-effects whatsoever.

Cheers,

John

[mike ellis]

The confusion about the lubricating effects of leaded petrol seems to arise because it is often assumed that the lead lubricates everything it comes into contact with. The fact is that it is never present as lead per se. It is added as Lead Tetraethyl/methyl to boost the octane rating and after combustion becomes lead oxides (harmful deposits which cause pre-ignition) or lead bromide which is volatile and lubricates the exhaust valves as it is swept out of the combustion chamber. The lead bromide is formed by reaction with ethylene bromides which are added to the fuel to reduce the formation of lead oxides, the lubrication was very much a side effect but a very useful one nevertheless.

 

Much was made of this in '60s advertising - remember Shell with 'ICA', this referred to Igniton Control Additive which was the ethylene bromides. In the same period US advertising for unleaded fuel denigrated leaded fuel for producing harmful deposits of lead oxide.

 

Hope this clarifies things a little bit.

[Richard Crawley]

Hi Richard,

Never heard of this, but I'd love to learn more. Do you have any info? Based on many letters and some articles over the years in TR Action from Dr MS Bingley, I'd assumed that lubricity issues were (ahem ) b-s. I've only done relatively few (trouble-free) miles on my PI unit with unleaded-compatible seals, but I've seen no ill-effects whatsoever.

Cheers,

John

Quiet some years ago when leaded fuel was first withdrawn from mainland Europe, I recall stories circulating about M/U’s seizing when used with U/L fuel; I think it was mainly in Germany. At the time, I also recall reading an article about experiments with new rotor/shuttle assemblies using high Graphite or Silicone steel which are, to a certain extent, self lubricating; it’s a long time since I studied Metallurgy & I’ve forgotten most of it but I believe high Chromium steel also has similar properties. I’ve not read any more since the original article & have not heard of any problems of seizing in the UK. I also have no idea if the current remanufactured rotor/shuttle assemblies use similar materials or if the problem (if there ever was one!) simply disappeared when Benzene & other such noxious substances was greatly reduced in more modern U/L fuel.

[Les Pettitt]

Hi Richard

Many thanks for the explanation of the rattle. Mine is exactly as you describe, more prominent on tickover or as the revs die down. It was just a bit disconcerting to fit an uprated MU and find it made a noise when my 30 year old original unit never did. It is not really norticeable in normal driving with the hood down but it is comforting to know that I am not the only with this rattle/clack/tick and you have come across it before.

Regards

Les

[boxer]

Hi Jemgee.

 

If you look back, you'll see many references on the forum. I've used 'Katie Raven-Smith' in the past for a rebuilt M.U.

 

You can e-mail k_raven_smith@yahoo.co.uk.

 

I have no tie up with the above, I was satisfied with what I had for the cost.

Dave

Now with the 4A & the 6 (wifes) both on the road.

where will i find website or phone no. for k.raven smith

[k_raven_smith]

where will i find website or phone no. for k.raven smith

Hello there,

k_raven_smith@yahoo.co.uk or 07977001571

Katie

[jemgee]

Spent most of the day with Malcolm who has changed injectors, hoses, MU, and petrol feed pipe, and fitted an underslung throttle kit I acquired last year.

Timing adjusted and pump pressure checked OK so the beast really was on song coming home. Thoroughly recommended.