18 replies to this topic

[DClarke1954]

Synopsis:

Old fart wins classic min in a contest and hasn't played with cars since he was a boy.

Car is a "gift-horse" so not inspected too closely, but it looks great but runs like a dog with 2 and half legs.

 

1275 Metro engine implant into Mk3 Classic (allegedly).

Driven off a transporter and placed on my drive under full choke with the engine screaming.

 

Have tried using it but....

Didn't/wouldn't run more than a mile before dying and needing a tow home. 

Wouldn't even start after it broke down (sounded like starter was lugging), symptom of ignition being far too advanced?

Retarded it and it would then start OK but not run with any power and was continually blowing back through the inlet side (no airbox on it).

See Carbon footprint on the carburettor piston.

 

 

Attempted fixes:

All valves checked/set to 12 thou' clearance on a cold engine.

The Mobiletron dizzy with no vac advance was ditched in favour of a brand-new Powerspark 65DM4 and all new HT leads.  New 0.5 Ohm coil (just in case), plugs all gapped at 35 thou'.

 

I set the timing using an innova 5568a timing light to 11° BTDC @1,000 rpm with no vac advance connected. 

It shows 14° @ 2,000 rpm and the distributor was rotated to give 32° BTDC @3,000 RPM (assumed it would be all-in at this point, did I need to go to a higher RPM?)

 

I connected the Vac-advance and took it for a test and it went better than it has done in the 3 months I have had it.  But while it would climb up the hill OK when I got to the top and took my foot sharply off the gas it blew back through the intake side again.   I took it on a gentler run with low gentle ascents and it felt like it was bogging down and it kept repeating this blowing back through the intake side.

Firing/detonating on the intake side suggests:

• its too advanced?
• Knackered sticking inlet valve?
• I'm a complete putz (don't answer that).

Anyway, its my toy/fun car and not my daily driver so its not desperate but I would appreciate the group's collective wisdom/help.

 

Thanks in advance for any pointers help.

 

Dan.

 

[68+86auto]

Your mistake is that you are making a lot of guesses. Test, don't guess.

 

You say you've set the timing to 11° at 1500rpm but then you say you've changed it to 32° at 3000rpm. This means that it is no longer at 11° at 1500rpm. It is most likely too far advanced, The factory likely specified well below 32° for a good reason.

From all the Lucas electronic distributors I've tested, they seem to have little advance and it take up to really high RPMs before it stops. You've bought a Chinese distributor which means the curve could be totally random and cause damage. I don't know what the mobiletron distributor is or the condition but I'd probably go back to that since they are an actual parts supplier so there may be some QC.

 

A 0.5ohm coil is incorrect for a 65DM4

 

in order to determine the factory timing, what is the engine number?

Please don't touch the carb until the ignition system is corrected.

[timmy850]

You can easily measure the rpm when the advance stops using your timing light. It might be 4000 or 5000 rpm (or something else if it’s got a longer or shorter curve)

I’d start again from idle, set it around 10 degrees, then measure every 1000rpm and note this down. A good starting point is 30 degrees total. Hopefully it stops advancing before 5000rpm

You’ll also need to sort out the fuelling in the carb (once the ignition is sorted) as too lean or rich, plus poor enrichment via the damper can also cause bogging & poor running

[DClarke1954]

Thanks both.

To clarify.

At 1,000 RPM I moved the dizzy so the timing marks showed c.10/11° and I left the dizzy there not fully locked off (can be moved with firm hand pressure).

My timing light lets me measure the advance (no changes to the dizzy) just press a button on the timing light) to alter when it strobes.

At 2,000 the mechanical advance is @ 14°.

At 3,000 the mechanical advance is at 32°, i.e. that's how far I have to press the advance-button on the timing light to get the pulley timing mark to align with the TDC mark again.

So as far as I know the starting point is 10-11 and the top is 32, although I did not rev it up beyond 3,000 and measure any further so maybe the dizzy goes further advanced?

 

I thought vac advance was all about part-throttle (demand) working?

I will go through it all again starting with c.10° at idle.

Yes, as you say timing first then fuelling.  When I got it the jet was wound all the way down to the bottom of the tube and the exhaust stank of unburnt fuel.

The carb rebuild was intended to take it back to a factory baseline at least so I could go from there.

 

Cheers fella's, much appreciated.

[ACDodd]

First problem I see here is the advance curve is way off. Consider 20 at 2000rpm to be much more the requirement. And 28 to 30 at 4000rpm.

Unlikely to run well until that problem is sorted. The you can start on fueling. Vacuum advance is for part throttle work only and adds timing to the figures above.

Ac

[Lplus]

Thanks both.

To clarify.

At 1,000 RPM I moved the dizzy so the timing marks showed c.10/11° and I left the dizzy there not fully locked off (can be moved with firm hand pressure).

My timing light lets me measure the advance (no changes to the dizzy) just press a button on the timing light) to alter when it strobes.

At 2,000 the mechanical advance is @ 14°.

At 3,000 the mechanical advance is at 32°, i.e. that's how far I have to press the advance-button on the timing light to get the pulley timing mark to align with the TDC mark again.

So as far as I know the starting point is 10-11 and the top is 32, although I did not rev it up beyond 3,000 and measure any further so maybe the dizzy goes further advanced?

 

I thought vac advance was all about part-throttle (demand) working?

I will go through it all again starting with c.10° at idle.

Yes, as you say timing first then fuelling.  When I got it the jet was wound all the way down to the bottom of the tube and the exhaust stank of unburnt fuel.

The carb rebuild was intended to take it back to a factory baseline at least so I could go from there.

 

Cheers fella's, much appreciated.

According to their website, the powerspark 65dm4 is apparently good for any A series  engine right from the cooking 998 metro up to the MG metro turbo.  I doubt it is perfect fo any of them but will no doubt work fairly well in any metro 1300 engine at  least.  The lucas equivalence number of 42664  apparently refers to the late MG metro and From my metro haynes manual it seems the various 1300s were set to between 7 an 13 degrees btdc at 1500 rpm with  vacuum disconnected.  Personally, I'd try 10 degrees btdc at 1500 as this was the MG metro setting.  Unlikely to be perfect since we don't know if your engine is an MG metro or otherwise modified but should provide a reasonable setup.

 

The coil should be about 0.9 ohm.  GCL143

[DClarke1954]

Thank you all so much for the advice and guidance, it is a long, long time since I did any of this.

I had another crack at it today (starting from scratch).

 

Engine warmed up fully.

Vacuum off and plugged on the HIF44.

RPM set at 1,000 on the idle screw and dizzy rotated to show 10° on the scale (and according to my Innova 5568 when I tell it to advance the strobe by 10° it lights when the pulley mark is at TDC this is what I expected and it confirms we are at 10 degrees BTDC).

Advance measured with the Innova at 2,000 was 14°, at 3,000 was 18°, at 4,000 it was 27° and it maxed out at around 4,700 at 32°.  Is this a bad curve?

I locked locked the dizzy position.

I shut the car down and re-attached the vacuum plumbing, started the car and the idle revs were now higher.  Adjusted back down to 1,000 rpm on the idle screw.

Rev-up and no more pop's-n-bangs in the intake side/Cone-filter.

 

Anyway, for pure S&G's I took it out and no more pop's-fart's etc. but a little more sluggish than I would expect.

Now either I still have it very, very wrong, or it may be time to look at the fuelling.  I pulled a plug and it wasn't all sooty on the electrode.

 

Please forgive me guys, I know I sound like a right-numpty.   I do recognise my lack of experience and so I have my BIL (MOT tester and 40+ years in the trade as a maint & service guy) coming round to help me on Sunday if it isn't raining. 

Edited by DClarke1954, 18 February 2025 - 05:12 PM.

[timmy850]

As AC mentioned, that curve is very slow to advance. It would perform with more advance sooner.

Now you have the process worked out, it might be worth checking the advance curve on your original distributor to see if that’s any better for your engine

[alpder]

Your earliest post, about your happy win, included the description of the car by the seller. I remember it said something like "a nice lumpy cam". Which feels like sales-spin on "doesn't idle nicely". Worth finding out what cam it has because - depending on just how "lumpy" and race-oriented the cam is - it may not ever be possible to get it to run right at idle.

[68+86auto]

You need to recurve the distributor. No amount of timing adjustment can compensate for the incorrect curve. I would see what the old distributor does.

[Lplus]

Your earliest post, about your happy win, included the description of the car by the seller. I remember it said something like "a nice lumpy cam". Which feels like sales-spin on "doesn't idle nicely". Worth finding out what cam it has because - depending on just how "lumpy" and race-oriented the cam is - it may not ever be possible to get it to run right at idle.

It might also explain the "sluggishness" if the OP isn't revving it enough to get it on the cam properly.

 

As is often the case with queries on here, there's way too little hard information on engine, carb and distributor spec to give a perfect reply.  The OP just wants to get the thing running on all 4 all the time - actions like recurving the distributor are way beyond his abilities at present.

 

If it has a hot cam and big valve head the non vacuum distributor might be better, especially if it has been set up with a cooper S type advance curve, but for now, using the average timing set up for 1300 metros on the powerspark unit would be a good start. 

 

Finding out the spec of the mobiltron distributor woud be useful too.

Edited by Lplus, 19 February 2025 - 09:07 AM.

[DClarke1954]

 

Your earliest post, about your happy win, included the description of the car by the seller. I remember it said something like "a nice lumpy cam". Which feels like sales-spin on "doesn't idle nicely". Worth finding out what cam it has because - depending on just how "lumpy" and race-oriented the cam is - it may not ever be possible to get it to run right at idle.

It might also explain the "sluggishness" if the OP isn't revving it enough to get it on the cam properly.

 

As is often the case with queries on here, there's way too little hard information on engine, carb and distributor spec to give a perfect reply.  The OP just wants to get the thing running on all 4 all the time - actions like recurving the distributor are way beyond his abilities at present.

 

If it has a hot cam and big valve head the non vacuum distributor might be better, especially if it has been set up with a cooper S type advance curve, but for now, using the average timing set up for 1300 metros on the powerspark unit would be a good start. 

 

Finding out the spec of the mobiltron distributor woud be useful too.

 

 

 

Thank you for the input, it is much appreciated and could help me determine my course of action.

I am at a loss really, the "Raffle Promotion" blurb declared a "lumpy cam" but speaking to the previous owner (who also won it and sold it back to the promoter after a year or 2) told me it had a standard Metro cam and nothing more.

 

So it is a 1975 mini 1000 (998) model with a transplanted 1275 Metro engine.

 

Where does that leave me?  What should the idle RPM be?  My Haynes says 1,000 for a 1975 1275GT or 1,500 for a 1990 onwards 1275 with electronic ignition.   

I have no way of knowing what date or where this engine comes from as there is no serial number on the block.

 

What should I do?  Guess?  Guessing is never good.

 

An engine that idles at 25% of its 5,750 red-line territory on the rev counter is something new to me, so I am in a strange place. 

e.g. My V8 Rangie idles at 750 and redlines at 5,000 (a very different kettle of fish of course).

 

So how should I treat this engine?  Set it's idle at 1,000 or 1,500?   Will this make it pick up a little better at the expense of fuel consumption?

 

Answers on a postcard to "Confused of Benfleet"   

Edited by DClarke1954, 19 February 2025 - 10:34 AM.

[Lplus]

 

 

Your earliest post, about your happy win, included the description of the car by the seller. I remember it said something like "a nice lumpy cam". Which feels like sales-spin on "doesn't idle nicely". Worth finding out what cam it has because - depending on just how "lumpy" and race-oriented the cam is - it may not ever be possible to get it to run right at idle.

It might also explain the "sluggishness" if the OP isn't revving it enough to get it on the cam properly.

 

As is often the case with queries on here, there's way too little hard information on engine, carb and distributor spec to give a perfect reply.  The OP just wants to get the thing running on all 4 all the time - actions like recurving the distributor are way beyond his abilities at present.

 

If it has a hot cam and big valve head the non vacuum distributor might be better, especially if it has been set up with a cooper S type advance curve, but for now, using the average timing set up for 1300 metros on the powerspark unit would be a good start. 

 

Finding out the spec of the mobiltron distributor woud be useful too.

 

 

 

Thank you for the input, it is much appreciated and could help me determine my course of action.

I am at a loss really, the "Raffle Promotion" blurb declared a "lumpy cam" but speaking to the previous owner (who also won it and sold it back to the promoter after a year or 2) told me it had a standard Metro cam and nothing more.

 

So it is a 1975 mini 1000 (998) model with a transplanted 1275 Metro engine.

 

Where does that leave me?  What should the idle RPM be?  My Haynes says 1,000 for a 1975 1275GT or 1,500 for a 1990 onwards 1275 with electronic ignition.   

I have no way of knowing what date or where this engine comes from as there is no serial number on the block.

 

What should I do?  Guess?  Guessing is never good.

 

An engine that idles at 25% of its 5,750 red-line territory on the rev counter is something new to me, so I am in a strange place. 

e.g. My V8 Rangie idles at 750 and redlines at 5,000 (a very different kettle of fish of course).

 

So how should I treat this engine?  Set it's idle at 1,000 or 1,500?   Will this make it pick up a little better at the expense of fuel consumption?

 

Answers on a postcard to "Confused of Benfleet"   

 

Standard Metros idled at around 650 - 750 rpm with the MG and MG Turbo up around 900 - 1000 rpm. I use 1000 rpm on my MG metro engined mini and about 900 on my modified 1098 clubmen estate. There is also fast idle of about 1300 rpm but this is set up from the choke control for use when the engine is cold so can be ignored for now.  Stroboscopic timing is not set up at idle but at fixed rpm, 600 rpm from 69 to 72, 1000 rpm from 72 to 83 and  1500 rpm from 83 onwards (according to my haynes manual) - presumably to ensure the centrifugal advance has begun to kick in.

 

Idle revs will not help pickup significantly.

[DClarke1954]

Standard Metros idled at around 650 - 750 rpm with the MG and MG Turbo up around 900 - 1000 rpm. I use 1000 rpm on my MG metro engined mini and about 900 on my modified 1098 clubmen estate. There is also fast idle of about 1300 rpm but this is set up from the choke control for use when the engine is cold so can be ignored for now.  Stroboscopic timing is not set up at idle but at fixed rpm, 600 rpm from 69 to 72, 1000 rpm from 72 to 83 and  1500 rpm from 83 onwards (according to my haynes manual) - presumably to ensure the centrifugal advance has begun to kick in.

 

 

Idle revs will not help pickup significantly.

 

Thanks for this, is there a "tell-tale" way to identify  bog-standard Metro engine from MG Metro?  Presumably the A+ block casting is the same in either case?

[alpder]

Your engine has had so much work ("Under the bonnet is a nicely modified 1275cc engine, everything was replaced when it was built. Has a stage 2 head with 21cc cambers etc that has literally just been re done. A nice lumpy cam with upgraded pistons and paired with an AC Dodd HIFF 44 carb, 3 branch LCB and full side exit Playmini exhaust system which of course sounds epic. The gear box has just been totally rebuilt meaning that this Mini wants for nothing. A full rolling road set up, resulting in a great 83.2bhp & 83.5 ibft, she will now be more like 90 bhp with the head just being redone.") that what it started out as becomes almost irrelevant.

 

Interesting that it's been on a rolling road - even though it's had work since. Might be worth finding out where that was and whether they remember it or have records. And if you can get the power/torque curve it'll give some clue whether it has a mad race cam that you'll never want to use as a daily driver or something that can actually be made driveable.