Engine only runs under too much advance

Post by **Mooney** » 10 Aug 2020, 17:30

Hi again, new day new problem.

Recently installed refurbished DG engine.

Can only run it under lots of advance. I've taken the carb apart, cleaned it, checked the jets, they're clear and i can see through them. Cleaned with a nylon bristle and sprayed with carb cleaner just for extra.

For the engine to run reasonably, i have to advance it to the point where the 5 degree BTDC mark is the red line on the left.

The mixture screw is 2.75 turns out

When i spray it running with carb cleaner it almost chokes out and dies, even with a little squirt (see video)

If this was running too rich, wouldn't it be more likely too need less advance?

Dizzy works, hall sensor works, new ignition coil, cap and rotor arm, vac advance works, HT leads test within resistance spec, new spark plugs.

Only thing i can think is that with the new engine, and good compression maybe there's not a strong enough spark in the ignition system meaning it will only ignite earlier in the compression cycle as there is less compression then?? Honestly feel like i'm clutching at straws here tho. I did take it for a drive the other day for a short while and when i came back the new coil was almost too hot to be able to touch.

Post by **Mooney** » 12 Aug 2020, 16:05

I decided to recheck my coil resistance from when i got it new a couple weeks ago. When i got it, it was within spec, 2 year warranty from NGK and it's now way out of spec already.

Primary should be .52 - .76 and is .90
Secondary should be 2.4k - 3.5k and is 4.4k

Is there a reason it would have failed so quickly? Something else in the ignition system maybe. But like i said i've got new rotor arm, cap, spark plugs, king and HT leads all within spec.

Attached a timing light video to show how far out it has to be to even run, and was difficult to start and get going as well, had to rev it a fair bit until it warmed up.

Post by **DoubleOSeven** » 12 Aug 2020, 17:10

I had this problem. My king lead had too much resistance alongside a dodgy rotor arm & a blocked carb. jet! That combo killed my new coil too. I had to also dial in loads of advance too until I swapped out the coil.

Post by **Mooney** » 12 Aug 2020, 17:34

I'm not sure if that's what killed my new coil,

Getting

King lead 2kohms, at spec
HT leads 6kohms, at spec
Rotor arm 1kohm, at spec

according to brickwerks post it's all within spec.

https://www.brickwerks.co.uk/brickwerks-blog/ht-lead/

They're brickwerks leads with less then 7,000 miles on them, everything else is new.

I've ordered a spark plug tester as well to see that the spark can jump enough. Apparently it's 10kv to create sufficient spark to start but 30-40kv for a good healthy coil.

Post by **Mooney** » 18 Aug 2020, 15:50

Ok so spark plug tester results

10kv consistent spark
20kv consistent spark

30kv no spark

wound back down to about 25kv
Arcing spark?

So I think this indicates my coil is bad as the other parts in the ignition system leading up to it all test within spec. Resisantces etc... new cap, rotor arm.

Any idea what could have caused it to fail early? I think my engine grounds are good but i'm going to get new cables run through that and the gearbox to the body.

Post by **Mocki** » 18 Aug 2020, 17:14

If we assume the coil was the correct one , and that everything else is indeed within spec , it looks like the coil was faulty.
at first I was going to suggest maybe the dissy was out of kilter in the drive, maybe 90° or 180° out , its common with rebuilt engines for the drive dog to be inserted out of line or the dissy to not seat in the drive dog , but I guess you are past that stage !

Post by **Mooney** » 18 Aug 2020, 18:52

The coil is part number 211 905 115 B which i got off autodoc and is made by NGK. Didn't want to get the brickwerks Bosch one as shipping to me is £30.

Would it be worth me getting a new coil off brickwerks at this point?

Re the dizzy being out by 90/180, that wouldn't effect my spark plug tester would it? Also i did get this running but only under a lot of advance. If the dizzy was out i shouldn't have been able to run it for any length of time right?

Also does anyone know the average output of their ignition coils in KV as i can't seem to find any reference to compare my results against.

Post by **Mocki** » 18 Aug 2020, 19:02

This maybe a silly point to make , but you did have the vac pipe disconnected from the dissy when checking / adjusting the timing?

Post by **Mooney** » 18 Aug 2020, 19:28

Yep and blocked off too

Post by **Mooney** » 21 Aug 2020, 15:22

Ok so decided to get a Bosch coil off brickwerks, bench tested resistance before i ever connected it to anything.

Primary .7kohms - happy with that
Secondary 4kohms as it stated in the web description, it's secondary is higher then spec - happy with that

Using a spark tester i couldn't get it to spark past 23ish kv and seeing as a new healthy coil should be able to achieve 30kv there must be something else wrong in the system. The only thing i haven't replaced at this point is the HT leads but they test fine.

Would a partially bad earth in the coil/ignition amp possibly be the reason for a weak spark? It fires consistently just not strongly. Maybe it's the recon engine being painted. Might take the earthing bolt out and wire brush the area.

With the engine running up to temp, i was getting 12v at coil + and ground to engine so it's getting enough juice.

Currently sitting at about 20 degrees btdc warmed up with vac pipe plugged, so definetly still an issue.

Post by **CharlieeBoy** » 23 Aug 2020, 00:05

Just to prove a point that it's not an earth problem with the coil or the motor, grab some jump leads or something and clamp onto the coil, engine, and a good earth point. You could also try running another live from the starter, or even another battery straight to the coil '+'. You said the engine had been painted, there's not paint down the spark plug thread is there? That would give you a bad earth and a super high resistance to the plugs and kill the coil..
Good luck!

Post by **sarran1955** » 23 Aug 2020, 07:36

Hello,

Mooney wrote: ↑10 Aug 2020, 17:30

Recently installed refurbished DG engine.

Can only run it under lots of advance.

Just a thought....check that the distributor drive pinion is correctly aligned...

Maybe 1 tooth out...
Maybe a photo in Haynes..
Cordialement,

Post by **Mooney** » 03 Sep 2020, 06:51

Just to update people on this, I think i'ts all working now. I feel like it Sarran might be right with it being 1 tooth out so i've ordered a piston stop so i can remeasure true TDC and can make my own 5 BTDC marking.

Was also having trouble accelerating, kept hitting a flat spot and discovered my accelerator jet is completley blocked! Need to find a friend with an ultrasonic cleaner and an air compressor now... but it's getting there

Post by **ajsimmo** » 03 Sep 2020, 08:53

The dizzy drive being a tooth out won't make your pulley markings wrong. It'll just mean the dizzy body sits in a different position to achieve the correct timing. It won't be that.
Do I understand that this problem arose when you fitted an exchange engine? If so, it could possibly be an internal build problem with the engine, eg wrong or incorrectly fitted camshaft, perhaps?

Sent from my ONEPLUS A3003 using Tapatalk

Post by **Mooney** » 03 Sep 2020, 09:44

Yeah it happened when i fitted an exchanged engine. Got it from Elite which i know doesn't have the best reputation on here but i was on a budget. It does sound like it runs fine but obviously i'd like a more concrete way of measuring this. If the camshaft was incorrectly fitted would it still run fine if i adjust my dizzy like i have?

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