Jump to content
Sign in to follow this  
Rem18

Metering Unit Overhaul

Recommended Posts

I admit that I have been a so called expert hahahaha on the PI system since the age of 9 when my father picked up his new CP TR6 directly at the factory at Coventry in 1970.

Sitting in the back of the smelly car accompanied by the whine of the Lucas pump I learnt a lot from the start.o

By the age of 15 I was already tinkering, trying to cool pumps and checking injectors.

By 21 I was well into vacuum gauges and fuel pressures.

So

While waiting for some parts to arrive I thought I would open up a metering unit I have swapped out.

It was leaking fuel from the datum cover.

I have always tuned the PI on the fly (I cross the Alps a lot and Colle Della Bonette at 2650m is Europe's highest and the PI splutters). I rarely choose a pass of less than 2,000m and you need to counter the rich effect of the vacuum.

So for once I thought I would have a go at the unit myself instead of sending it back to the UK.

As It was leaking I was convinced it was a Diaphragm.

But both the unit and distributor ones are fine.

 

So I would like to hear from someone who has overhauled a unit as I would like to try and see myself.

FYI

Unit had Red springs in it and already there I suspect thats thats not right. The unit always ran rich at idle even when I tuned it down and I think that is due to those springs being for the Tr6 CP which has the idle screw.

I would also like to hear from someone who has an idea why fuel was leaking out of the datum cover if both the diaphragms are ok? The unit also turns over ok and hold vacuum with track movement on suck etc.

 

If it wasnt such a pain taking the unit of and on due to the dreaded third bolt I would love to road test settings other than the top screws.

The Lucas manual says to take it all off via the pedestal, but I have always been worried going that route due to end float stories. Although the manual doesnt seem concerned.

Thanks

Tony

Share this post


Link to post
Share on other sites
Guest ntc

There is an old saying with the Pi system if you do not know what you are doing you will fail.

Share this post


Link to post
Share on other sites

Well Neil True

But I did say I had a lot of years experience on PI right from nearly when it was introduced.

I started at 9.

I have never been let down by it (except once when out TR6 stayed stored for 18 months)

In fact I have only ever been towed once in nigh on 50 years of Tr6 and 5 and as I said that was due to long term storage.

I even got home on a blown layshaft bearing.

Been tinkering for all those years and done about 200,000 miles on it all over the alps (used to run a 50 alpine passes in 5 days jaunt every year on the Tr5 and never got stuck).

I am a terrible mechanic probably but I have always got on with the PI.

Have you done 200k on it all over the mountains without ever being towed? hahahahhaha

 

Anyway still interested in having a go.

Worst scenario I will send it back to the UK to get it overhauled, if I dont get on with it.

This one lasted 25 years so it might be a few weeks before I need to carry another as a spare...

Still asking if the diaphragms are in tact why was it leaking fuel from the datum cover?

T

Share this post


Link to post
Share on other sites

Leaks from datum cover are always from diaphragm seal, check very closely

and I am sure you well find some perforation in the seal.

 

Harvey S.Maitland

Share this post


Link to post
Share on other sites

Heh Thanks Harvey.

Thats Part 48 in the exploded for the distributor right not the control diaphragm?

I did look and couldnt see perforation but maybe it is micro or moved out of place or something, I will try putting a light behind it.

But anyway I would like to overhaul the entire unit and test it on car, to learn more.

Can anyone suggest where I can buy overhaul parts and if its enough to clean everything up in petrol and just wd40?

I would appreciate some info about the spings too. As I said my TR5 had this unit and it has red springs. I am pretty sure that means it was a TR6 unit setup and would explain why I always had the mixture screwed right out and never needed any choke to start as it ran rich at low rpm.

Be great if someone could also confirm if removing via distributor is not as complicated as I have heard (manual doesnt make an issue but I have heard about timing problems after. Would be a lot easier replacing each time.

Thanks

T

Share this post


Link to post
Share on other sites

Maybe Neil things I am crazy but it looks and the manual says its easy (and I dont think they would if it was hard) I have already had it open and closed and I much prefer to work on a clean table things than a dirty garage in the hot or cold.

Seems straight forward if I can get the parts. The distributor turns, so if I can get an overhaul kit and if I could find an easy way to get the unit on and off I am sure I could road test it and then get some exhaust gar readings after.

My feeling is that each car is different and a bench tested unit is only a starting point, you need to test the mixture according to engine performance, vacuum, fuel, altitude and all sorts. So I am an advocate of road tweeking fuel and ignition.

It would certainly make a spare unit if I can clean it up.

This is the overhaul page in the manual for who is interested?

http://www.lucasinjection.com/Lucas%20Mk2%20manual%20page%2021.htm

Share this post


Link to post
Share on other sites

Talk to Malcolm Jones at Prestige Injection. He can supply seals etc.

and give any advise you may need.

 

 

Harvey S.Maitland

Share this post


Link to post
Share on other sites

Talk to Neil Ferguson 07977001571

Stuart.

Share this post


Link to post
Share on other sites

Thanks guys.

I am going to have a go at it myself next month.

 

Would still like to hear about any experience whipping unit off via distribuutor pedestal as it would sure be easier on the hands..;)

Share this post


Link to post
Share on other sites

Thanks guys.

I am going to have a go at it myself next month.

 

Would still like to hear about any experience whipping unit off via distribuutor pedestal as it would sure be easier on the hands.. ;)

Thats why I said talk to Neil, he will tell you what you need to know.

Stuart.

Share this post


Link to post
Share on other sites

Yes but Neil you are being vague again.

If it's with the pedestal then it's 5m.

If it's via the three bolts without pedestal it's a pain.

I have always understood there are implications if you remove via pedestal.

Are you saying you can bolt off and on taking the lot on without any possible affects to timing?

Can someone confirm that it's fine taking the whole lot off?

Share this post


Link to post
Share on other sites

Not having hands the size on Neil's daughter I find one of these (the only picture I could find) really cheap socket wrenches fits in and replaces the rearmost two of the three bolts relatively easily.

 

http://www.ebay.co.uk/itm/1-Set-1-4-Inch-Screw-Nut-Ratchet-Wrench-Spanner-6-Sockets-10-Screwdriver-Bits-/142426852918?hash=item21294d4e36:g:2mAAAOSwjvJZULnT

 

Alan

Share this post


Link to post
Share on other sites

Exactly Alan.

So your saying best off without pedestal?

Is there really a risk a putting something out via pedestal?

As for Neil's daughter can she pop round and do my wire wheels too?😜

Share this post


Link to post
Share on other sites

I take mine off with via the pedastal - no issues, a lot easier, just be careful, lift very slowly and leave the gasket in place without any damage.

 

best Bill

Share this post


Link to post
Share on other sites

Ahh Bill thats what I was wanting.👍

Not only is it easier but it means you can get at the pedestal seals too and generally look at fuel and electric gear in one.

 

So there is no real risk regards upsetting end float and stuff, which is the reason I have always avoided before.

T

Share this post


Link to post
Share on other sites
Guest ntc

I said both and you have to remove the drive dog (yes thats the one that drives of the cam also drives the dizzy and oil pump) and yes you do have to time it if you get it wrong as it rotates as you remove.

Share this post


Link to post
Share on other sites
Guest ntc

If you know what you are doing and work out the logic,no everything is easy to get at and a lot quicker.

Edited by ntc

Share this post


Link to post
Share on other sites
Guest ntc

At least once it should be done like that to get at the pedestal seals.

Yep once you have done it,got it right you would do it like that everytime.

Share this post


Link to post
Share on other sites

Rem18

 

I recently replaced my MU (refurbished by Neil Furgeson), first setting engine to TDC, then removing MU and pedestal after removing the dizzy.

Replacing it all, I attached the 'new' MU to the pedestal and installed that assembly to the engine, checking I had the MU timing correct as per the manual. It needed a couple of attempts to get the drive engaged correctly the my satisfaction...

It all went back well and once the fuel got through to the injectors (that took longer than expected!) it fired up and has ran really well...

 

Cheers

Ian

Share this post


Link to post
Share on other sites

Hi Ian

I am used to all the rest, just never tried with pedestal off.

Your right it does seem ages before injectors prime (best to hold virtically).

Hope you replaced the pedestal seals at the same time?

T

Share this post


Link to post
Share on other sites
Guest ntc

Rem18

 

I recently replaced my MU (refurbished by Neil Furgeson), first setting engine to TDC, then removing MU and pedestal after removing the dizzy.

Replacing it all, I attached the 'new' MU to the pedestal and installed that assembly to the engine, checking I had the MU timing correct as per the manual. It needed a couple of attempts to get the drive engaged correctly the my satisfaction...

It all went back well and once the fuel got through to the injectors (that took longer than expected!) it fired up and has ran really well...

 

Cheers

Ian

Hi Ian

I guess the oil pump drive made it take a little longer? there is a way round that ;)

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.