Distributor (Lucas 43 D) clamp loss ANS: Yes and now extensive d.i.y. KNOCK SENSOR discussion (kit ordered)

[anthony1956]

Knock sensor chat starts here https://www.caterhamlotus7.club/forums/topic/276514-distributor-lucas-43-d-clamp-anyone-had-one-of-these-lose-its-grip-fail-to-clamp-the-distributor-ans-yes/?do=findComment&comment=2621644 which is towards the end of page 2.

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Covering the bases here. Probably my error when retightening it, but I do seem to keep finding the timing has changed. 

Nothing surprises me any more with this car being (nearly) 40 years old.

Anthony

Edited September 22 by anthony1956

[OldAndrewE]

One like this I presume Anthony

They can stretch such that the clamp gap closes up before the distributor is gripped.  When you have it tight can you move the distributor by hand?

[Miker7]

How much is it losing timing?

If you can turn the distributor by hand, how much does it move? If its only a little bit do you have a spring washer under the bolt head that goes into the block?

[anthony1956]

@oldandrewe Yes exactly one of those. Yes it is looking a bit out of shapish. However, not closing up where it shouldn't. 

and @MIKER7 No can't turn it by hand, checked that, in fact always check that. It lost about 6 degrees, or 2/3 of a cam tooth. "A" tooth defined as one tooth AND one gap on the sprocket. Given a cam degree is half a crank degree that'll be 12 degrees on the cam I guess. 

I THINK what's going on is that I am not tightening it enough so that when driving it gradually loses its grip just a bit at a time. I did it up much tighter today and it hasn't budged. Also previously I was having to put a lot of force on to the dizzy to turn it to get enough advance. So I Moved all the HT leads one-to-the-left. I.e one contact clockwise given the rotor goes anti-clockwise, which retards the dizzy by 45 degrees, and then I can advance it to get my 6 degrees nice and easily. This has worked today so whether the fact it was forced top far and slipped back or was not tight enough or both is as maybe was. 

I picked up the 45 degree trick for a 2006 post of chevy owners, which I find remarkable. 

All the above is subject to my timing should be 6 degrees BTDC no 1 compression stroke. I am not at all certain the numbers I mention above stack up in the context given cam degrees are half crank degrees. 

If you could sort me out in that regard I could stop worrying about it 🙂

My cam sprocket has 40 teeth so 360/40 = 9 degrees, but do I then want 2/3 of a tooth (defined as above) or if this is only half, then 4/3 of a tooth i.e. 1 1/3 teeth? We do not have any crank markers that are capable of use. 

edit @OldAndrewE the one I found had two holes for bolts..

Have to admit I am very wary of replacing it as it looks like one has to lift the dizzy out completely and knowing me I would put it back a tooth different

https://www.holden.co.uk/p/distributor_clamp

Anthony

Edited September 16 by anthony1956

[anthony1956]

I am clearly wrong about doubling the timing, but it's doing my head in:

[anthony1956]

a bit bent but still working

[Miker7]

Cams spin at half engine crank speed, as does the distributor - 360 degrees of distributor/cam shaft is 720 degrees of crank. Is this what you mean about doubling?

[anthony1956]

On 16/09/2024 at 22:03, Miker7 said:

Cams spin at half engine crank speed, as does the distributor - 360 degrees of distributor/cam shaft is 720 degrees of crank. Is this what you mean about doubling?

yes, I see you illustrated doubling.

Holdens want £6 to deliver their £20 item. Not willing to be ripped off like that. Got one from 

Edited September 18 by anthony1956

[anthony1956]

So I did it tighter and today, for the first time, I got her started at the first attempt. It wasn't easy, but she started. I checked the timing and it has not changed from yesterday.

 

[Gridgway]

There's something not right going on.  My BDR starts easy peasy.  Doing the dizzy up so it doesn't move is similarly easy.  Timing just doesn't move in the normal world! 

Is there something else going on with fuel or sparks?

[anthony1956]

Morning Graham, well.. there has indeed been lots going on! I THINK the timing changing overnight has (may) have been sorted with the dizzy alteration. Yesterday the fuel pump relay failed so that was a distraction now fixed as of midnight last night. I THINK I was also not doing up the clamp tight enough - bearing in mind I was forcing the dizzy clockwise to get enough movement. Shifting all the HT leads clockwise by one dizzy contact gave me 45 degrees and put my adjustments sort of in the middle instead of at the end. So I think the mix of forcing it and leaving it not tight meant it slipped back. As AndrewE noted, my clamp is practically bent to useless, but not quite completely.

After the emissions control today, assuming I get down there I will look at setting up for ease of starting etc. Maybe some new plugs to celebrate.

Edited September 18 by anthony1956

[anthony1956]

today the dizzy clamp was done up proper tight by a proper mechanic; it's def time to replace it. 

 

it was quite amusing really, I turned up for the gas test armed with all the tools, gas analyser, carb balancer, strobe gun to name a few, he took one look and got interested, said his dad knew how to do this so I explained Dellorto screws etc and without further ado he understood and had it all sorted with record figures in, maybe 15 - 20 minutes. Can't beat a career mechanic!

 

Edited September 18 by anthony1956

[anthony1956]

UPDATE @OldAndrewE looks like your proposed suggestion was spot on. Even with a pro setting the timing, by the next morning it is way off, so it is time related not road miles related pretty sure. Not looking forward to the replacement process as I suspect the carb and the dizzy complete have to come off .. 

so that means:
mark the dizzy body to the block (tippex)
mark the rotor to the dizzy body (tippex)
extract dizzy, noting any movement of the rotor as the helical gears disengage
remove old and install new clamp
install dizzy, moving rotor in reverse to match that small shift when extracting it, so the gear mesh correctly
tighten the new clamp.

Chances of not screwing up timing and having to do it again seem remote.

Edited September 19 by anthony1956

[OldAndrewE]

I can't imagine what is going on.  When you were driving the timing stayed correctly set (or I assume it did as I am sure you would have notice a change in performance).  Are you saying that with the car sitting in the garage the timing is changing?  When you say way off, by how much?

Anyone else got any ideas?

[anthony1956]

Yes not when driving, which is never for very long so I guess that's why I have not noticed, but over the time of a night, so 12 or more hours, it goes out, consistently, every morning it's way off again.Off by several, actually a LOT of degrees retarded, so it's gone from being advanced to retarded. Wonder if I should set up a time lapse camera over night.. that's not as odd as it may sound as I have a GoPro I am testing for long term recording so this would simply be something to point it at.

 

[OldAndrewE]

Still cannot think how that is happening.  One thing that springs to mind is that you have a vacuum advance distributor with the vacuum bit removed and the moving plate anchored in place.  Have you checked that that anchor is still in place?  My Lucas non-vac distributor just has a single fixed plate

[anthony1956]

I have no idea, but can check my extensive photos and see if any clues appear - as in I don't know what to look for. Time lapse camera is now in place so if there is any slippage over night we will see it tomorrow

so if there is no movement it must be supernatural interference; the images show the clamp, the bolt, nut and the base

duck tape as ever playing a crucial role

 

Edited September 19 by anthony1956

[anthony1956]

@OldAndrewEDo any of these show what you are asking about?

They all look the same to me..

 

 

 

 

 

 

Edited September 19 by anthony1956

[anthony1956]

@OldAndrewE and built up a bit more

 

 

 

 

 

Edited September 19 by anthony1956

[OldAndrewE]

If they are moving then that would alter the timing but probably in an inconsistent way

[anthony1956]

aha, ok, far as I know all is still in place, but I will have a look now. Time lapse notwithstanding 🙂 ..seems to me if the dog bone were detached the timing would be all over the place not to mention the spark.. anyway going to have a look now

Edited September 19 by anthony1956

[OldAndrewE]

Yes, agreed it is a long shot and I would expect the effect to be quite random

[anthony1956]

ok looked and here's the pic, given I know where the dog bone is it's easier for me to see it; it's under the earth strap ; in pic two I have added a couple of lines to show where it is. And the ignitor is solid, won't budge at all.

Long shots r us at this stage.

Edited September 19 by anthony1956

[anthony1956]

So it looks to me like it slips over night, but it may be it slips during use and I don't check the timing at the end of the day, and it starts easily because the engine is hot. But today I have corrected the timing, the engine barely warm after running for only moments, so if the timing is off in the morning, it is happening over night and we should be able to see it happening. However, if not then it occurs during engine use, which is much more intuitively likely and I can test for that by giving it a run and then checking the timing. 

ah, one twist, if it happens during engine cool down after use, that would be both in use AND "overnight" in play. You won't be surprised to hear once the engine is running I don't let it cool down until the end of the day.

And a note: since I set the timing usually when the engine is hot, the cool down has opportunity to change things - even though it shouldn't, all of this reverts to the clamp having had its day, I think -  and perhaps hope because otherwise we are in to jackshaft gears worn and that sort of thing, but it seems to me 41,000 miles should not be anything like enough for that sort of wear.

 

Edited September 19 by anthony1956

[anthony1956]

1 hour ago, OldAndrewE said:

One thing that springs to mind is that you have a vacuum advance distributor with the vacuum bit removed and the moving plate anchored in place.  Have you checked that that anchor is still in place?  My Lucas non-vac distributor just has a single fixed plate

Mine is a Lucas 43D which is a non vac dizzy.