Misfiring

norried · Apr 30, 2018

Ok after bolting everything back on the engine I got it started but it runs like a dog. It doesn't seem to be firing properly on cylinders 2 and 3. If you pull the leads off 1 by1 the engine nearly cuts out if you pull no1 or 4 off but you can take 2 and 3 off and it makes very little difference.
I'm thinking the head gasket has failed between 2 and 3. I've checked the tappets and there fine and I've swapped over plugs and it's the same. It appeared to run Ok before I removed buts and pieces however the exhaust was blowing badly and the manifold wasn't sealed well.
I'm thinking of trying to borrow a compression tester to confirm my thoughts. I just hope it's not something more serious.
Any other suggestions or thoughts?
Thanks
Norrie

John S · Apr 30, 2018

Check the HT leads sequence from the dizzy to the cylinders.

norried · Apr 30, 2018

Yep done that. 1342. Starting at the top right of the dizzy which is what it was before.

John S · Apr 30, 2018

Noted. Next move if it was me would be to recheck the ignition timing. I'd try a static timing on the first cyclinder. Use the thumb technique to guage pistol cycle etc. Keep the faith it don't sound fatal; engines are resilient.

Extreedoc · May 1, 2018

Do the compression test.

Simon Perks · May 2, 2018

Check plugs to see if they are showing signs of ignition first (black or wet or light grey) and adjust the mixture.
Are you certain about top right on the dizzy? best to check with TDC - mine was 180deg out .. so Nr one is where 4 is on yours.
Check the leads -
Check the valve clearances -

norried · May 2, 2018

I've now done a compression test. Getting 1-130, 2-100, 3-125, 4-130.
So ok No2 is down but not that much to indicate head gasket failure. I’ve done the tappets and set the ignition timing.
Was thinking of going electronic ignition so might just order a complete new dizzy with leads etc.
Got new plugs coming today although not sure I’ve ordered the correct ones.
How can you tell if it’s a high or low compression engine?
Thanks.
Norrie.

Sting14 · May 4, 2018

If your engine number starts with:-
361 it's a 8.1 5 bearing
363 it's a 7.1 5 bearing

901 it's a 8.1 3 bearing
902 it's a 8.1 3 bearing
903 it's a 8.1 3 bearing

904 it's a 7.1 3 bearing

If I'm guessing right
duck egg coloured engines are 3 bearing
Red coloured engines are 5 bearing

I just recently converted to electronic ignition. It was well worth the money it now starts everytime first time. I bought my electronic ignition kit from "powerspark" I also renewed my starter motor and solenoid as well so the whole ignition system is totally new.

norried · May 4, 2018

Yeah it starts with 901 and duck egg blue. So a 3 bearing 8.1 engine.

Thanks

Norrie

Blackburn · May 4, 2018

Better check for 5 main bearing is the ribs on the side of the block 3 main bearing does not have them , some one may have painted it a diffferent colour. Pic from Turners website.

Misfiring

norried

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John S

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norried

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John S

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Extreedoc

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Simon Perks

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norried

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Sting14

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norried

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Blackburn

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