Cold running - Sorted!

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TheMegaMan

TheMegaMan

Well-Known Member
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516
Location
Cambridge
Landy is finally back together again, and almost ready for an MoT, I think. Just need to get the headlights roughly aligned, and book a test.

...so went to take it on its first 'drive', to position it in front of a wall to check the beam. But didn't manage to move it. While I'm not used to driving a car with a manual choke (I've not driven the Landy for the last 10 years or so), I'm pretty sure there's more to this than just user error.

Symptoms are that I can't get the revs high enough to be able to move it.

The engine starts OK on the choke when cold, and idles OK, but any attempt to rev it, the engine kind of dies. As it warmed up a bit, it ran OK with the choke pushed in more, but it still just coughed and spluttered when trying to apply any throttle, with an occasional backfire. I needed to press the accelerator really slowly and gently to get the engine to speed up, but when I started to lift the clutch, it just slowed again and I had to dip the clutch to prevent it from stalling. There seemed very little power from the engine.

New coil and plugs. New Webber carb. New electronic dizzy. I'm hoping timing is just out, but it seemed OK when I set it before.

Any suggestions, please?

It did run pretty well a few months ago (but vehicle wasn't mobile, so no attempt to actually load the engine. It was also a lot warmer then and less damp in the air. But I think there's more to this than just being cold.

So *very* nearly done!
 
Sounds like it is running lean, possible blocked jet?
There is no two ways about it, carbs are a pita!
 
Yeah, I've been looking around and thinking about this, and I'm wondering whether the accelerator pump isn't working as it should. Not sure how to remove the jets to check them...more Googling required.
I have been pondering whether to investigate a MegaSquirt conversion!
 
When it came to tuning basic carb equipped motors the main things I used were my ears to get the timing right on after getting the static timing correct and a Gunson colortune [ still available ] to get the mix correct at slow speed, fast running and acceleration. This clever device allows one to look into the combustion chamber while the engine is running and check/adjust the mix as needed. Easy to use, just follow the instructions and colour chart.
One thing, engine must be up to running temp. If it wont run with choke in keep it out. Turn up the slow running more than would be normal and readjust when things are nearer the mark.
 
A little playing around this afternoon.

Carefully squirted a bit of easy start around the carb and vacuum joints when engine was running, an no change in engine speed or sound. If I'd squirted any on any leaks, I hope I would have heard some effect of that. So I don't think I have any (significant) air leaks.

Removing the air elbow and looking (carefully, since I've had a few back-fires) down the body, the engine ran well enough to keep going with the choke fully open. On dabbing the throttle, the engine nearly died every time, and there were no extra quirts of fuel into the venturi. My understanding is that I should see a squirt from the accelerator pump when I do that. So I guess something is blocked.

I removed and cleaned the idle jet, which seemed clear and didn't help anything. Not too surprising, really, since idling is the one thing that's working fine.

I've now removed the carb and will dismantle the body tomorrow and check the rest of the jets, and also the accelerator pump. Not risking doing this is situ, given my record of losing big bolts on my gravel driveway....no way will I risk losing the fiddly little things from my carb!
 
tottot said:
When it came to tuning basic carb equipped motors the main things I used were my ears to get the timing right
Click to expand...

It was mostly correct when I got the engine running a while ago, and I've not changed the timing since, so that *should* be OK...

tottot said:
and a Gunson colortune [ still available ] to get the mix correct at slow speed, fast running and acceleration. This clever device allows one to look into the combustion chamber while the engine is running and check/adjust the mix as needed. Easy to use, just follow the instructions and colour chart
Click to expand...

I have a feeling I might have one of those here! I think I put it away, and carbs don't really have a lot of adjustment, but maybe the colour chart would at least confirm that it is lean on acceleration, as suspected. I'll try and give one of those a try once I've cleaned the internals, if that doesn't fix it. Thanks for reminding me that these things exist!
 
kermit_rr said:
Definitely something gummed up from sitting with fuel in the carb. Or the diaphragm in the accelerator pump has split
Or both
Click to expand...
OK, thanks. It's good that this is all pointing towards carb problems. Fingers crossed it'll be obvious when I open it up tomorrow.
 
Agreed, sounds like the idle mixture is ok so its starts and indels but goes weak on pick up. If it speed up on a throttle blip then dies its main jet only, if it speeds up ok if you throttle up very slowly its accelerator pump only. Yours sounds like it could be both acc pump and main jet. Either split diaphragm and blocked jet of a blocked passage if there is one shared.
 
Thanks so much for the comments over the last few days, chaps.

Took the carb off the Landy and lifted the lid on it today. Was very surprised by the state of it! It was brand new when I got the engine running before removing it, so it's only had maybe an hour total running time, and zero miles on it. But I suppose it did then sit for about 18 months while I dismantled the rest of the Landy and built it up again.

Anyway, there was crap in the inlet mesh filter, the float chamber had lots of crud in the bottom, and the same in the accelerator pump chamber. The accelerator jet was also completely blocked. So cleaned it out, reassembled everything, and now it's running nice and smoothly, and picks up very well on the accelerator. :D

So it's now moved under its own power for the first time in about 12 years. Gears and clutch feel good. Steering is as heavy as it always was. Brakes work, but aren't particularly good. But all brand new, so I hope just need a little running to bed them in. About ready for an MoT to check my work, I think!
 
lynall said:
My advice would be filters, more than one and really fine as well, plus carry spares.
Click to expand...
Yeah, that's what's particularly annoying, since I have the V8 filter plumbed into my system. I briefly took it out a few months ago when I couldn't stop it leaking, but managed to resolve that and refitted it. I guess the crud could all have got in there for those brief moments when I ran without it.
I may well fit a cheapie plastic filter in there, too. Would be useful to be able to check fuel flow, as a bonus.
 
rob1miles said:
Do a few really hard stops to bed the shoes before they get glazed by heat. Then re-adjust, they should they stay adjusted for a while.
Click to expand...
Yeah, that was my intention, but that'll have to wait until my drive on the way to the MoT test. Obviously I'm not allowed to drive it on the road, yet, and I can't get up enough speed on my driveway to actually do anything useful!
 
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