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elite 3-cylinder 911 engine


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My recently acquired elite - get it going first...So the idle (and running) is lumpy, and pulling the ignition lead on cylinder 2 has no effect. (All the others do)

Lovely spark with a spark tester.

Lovely compression.

I removed the air filter and squirted easy start into the  Delorto carb mouth, no change.

What next?

Thanks

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Tom,

Welcome to the forum.

Sounds like you have an idea of what your doing given your methodical checks so far.

The other checks I would do is measure and adjust the carb float height to mm precision. I know you've sprayed atomised ether into the venturi with no noticeable improvement, but the float height is critical on these engines and poor adjustment make the engine run like a box of spanners.

If the car has been sitting for a long time, I would whip out the jets and make sure they are clean. If the fuel is of unknown age, unplug a fuel pipe and pump it out and start with 10L of fresh fuel.

Has the engine been apart? If so, put it to TDC and check the cam pulley positions. Mechanics often get these a tooth out which can cause poor running.

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OK next week I will check cam timing and float height, but it's just a single cylinder not firing. Could a valve (inlet? - Exhaust valve stuck would probably blow the carb apart) be stuck closed? That way you'd get good compression but no airflow? I will remove the cam cover and see what's happening there too.

I have hooned it up and down the road to run in the fresh fuel, but it was pretty low when I got it so I wondered if tank scrapings had been sucked in. I've already cleaned out the three jets easily accessible from the top of the Carb, but the"no change" on ether implies it's not fuel flow.

Thanks for the ideas. More welcome.

 

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So as I understand it, there is comp on all cylinders, it is running on 3, you mention a good spark, I assume this on the offending pot and at the right plug not holding the lead against the head etc.

I would try this , get it going and test for sucking on each carb trumpet, if 2 is sucking well and in rough balance with the others with comp and spark OK , it must be fuel. If you introduce fuel into the trumpet with the engine running it should fire up on that one cylinder. 

If it still won't fire,, look at the inlet manifold, and the carb o ring seals or possibly damaged inlet manifold. The other thing to try is the vacuum pipe for the headlights, if they are electric, the tapping may still be there but not properly blanked off

if the valves stuck down they would hit the pistons, besides there would be no compression,.

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I wondered about a stuck valve but there are 2 per cylinder and I'd doubt both would be stuck - OK (and I'm making assumptions here!) I'm guessing it wouldn't help but surely some fuel would get in?

Equally, I'd have thought the overhead cam would complain if a valve wasn't moving when depressed on rotation?

 

Is the price for that bit in Yen or £?

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If you've got compression and spark on all cylinders then the likely culprit is fuel. As you say, not fuel height as it's firing on the other venturi, so I'd guess you have a blocked jet. Time to strip the carb a bit and look for bits of stale fuel jelly.

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Four cylinders firing!

All jets in no 2 carb blasted through with solvent and compressed air, nasty looking black stuff coming out of the bell mouth, then vroom vroom a whole lot better. Managed to take the car for a quick spin next I'll get the alternator working. Cam belt on the to do list.

I'm hoping that running the engine a little with carb cleaner in the fuel will sort the rest out, as it sounds and pulls OK.

Thanks for the advice everyone

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That's the sort of fix that's often hoped for: No parts, just minimal consumables and a bit of effort.

I did think, after my last post, I could have suggested blocking off the trumpet of the non-firing cylinder and crank/ run the engine. So letting atmospheric pressure push fuel through the jets, but it's far from certain and can sometimes more-securely lodge the debris. So, glad your method has appeared to work.

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Thanks so much for the help.

Such easy access to friendly advice helps firm up the best solution.

I remember trying to fix ancient cars as a teenager with just "common sense" - out on the street with a few spanners working things out from first principles.

I learned that a carburettor is a complex thing.

And a gearbox is very heavy.

  • Haha 1
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  • 3 months later...

OK timing belt replaced...using the Stanley knife method recommended by John Walsh so thanks for that.

Alternator bearing shot though - cheapo Chinese unit.  Anyone recommend a new cheapish replacement? I'm sure an uprated model would set the wiring on fire.

2018-01-18 13.19.09.jpg

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