question Distributors for the Gaz

[iannima]

This progressive sub-section of the HMVF has been allocated the task of generating more technical questions ...

So here is one

My Gaz came fitted with a Radio Screened DDR produced distributor:

These are an absolute pain to reset, and are also prone to short circuits as refitting the cover is easy to pinch one or two wires. I have as many as four of these in various states of decay. Two are serviceable and one is fitted to the engine. Much as it now works, and aside from the fiddly nuisance that it is, I intended to replace it as it seems rather worn with some unsprung movement in the backplate that cannot be any good.

[iannima]

I ordered from Bulgaria a new old stock distributor, which is the one originally fitted to the Gaz:

This is a more traditionally shaped one with a bakelite cap and an external condenser. It looks very nice :-)...

[iannima]

However... I cannot manage to get it to work and I am rather annoyed at having wasted €120. I tried with a friend who is very knowledgeable about Gaz side-valve engines, on Saturday last and again yesterday but with no joy. I consulted another friend on the German forum and he suggested removing the back plate and flip the cam shaft by 180 degrees, in the belief that it might have been trying to fire cylinder 4 when it had to fire cylinder 1. I did that, before the refitting yesterday, but again no joy. Having consulted friends again there are now two theories:

 

 

1. As the DDR distributor was not originally intended for the Gaz, the cogs to which the spindle connects might have been adjusted to fit the DDR distributor. To put this right, the oil pump would have to be removed. I am MOST reluctant to go down this route, as the vehicle at least works with the DDR distributor, and I fear getting into a situation when it does not work with BOTH distributors;
   
2. the other theory is that there is something deeply wrong in the assembly of the new distributor. It has been suggested to me to check the position of the rotor arm, when the points are open, relative to the segments on the distributor cap. Now the segments are in position 7 o'clock; 10 o'clock; 1 o'clock and 4 o'clock, in firing sequence. Keeping the body of the distributor fixed and rotating the shaft, I can see the points opening instead at: 8 o'clock (perhaps even later than that but not yet 9 o'clock, call it 8:30 and similarly for the other three positions); 11 o'clock; 2 o'clock and 5 o'clock. That is the points open when the rotor arm must be definitely way past the segment. I have tried several things, but it seems to me that it will always do that.
   

 

What can I do?

[RMS]

when you say you cant get it to work do you mean no spark or cannot get the timing in the right place?

[iannima]

Happily sparking away, but the engine does not fire. To my mind it is DEFINITELY a timing issue, i.e. the spark happens at the wrong time.

[RMS]

Whip plug no.1 out and turn the engine over until its on the compression stoke for no.1 (stuff a bit of tissue in the plug hole and it will pop out when compression builds) turn the engine until the piston 1 is roughly at the top then check the rotor arm is pointing to no.1 lead on the dissy cap. then check the rest are in the correct firing order (probably 1-3-4-2, clockwise or anticlockwise??).

 

if its pointing toward no.1 then loosen the dissy and get an amigo to turn in either direction by a few degrees whilst trying to start the engine, should find the correct spot, then timing can be refined with the engine running.

[iannima]

Sorry, done all that already to no avail.

[iannima]

Sorry, perhaps I need to rephrase what I think the problem is. If by a timing problem, we mean a matching between the position of each piston and the spark coming from the distributor, then this is probably not the issue. Indeed this problem would only be seen when the distributor is mounted on the engine. The issue I see is instead ENTIRELY internal to the distributor and has nothing to do with the position of the engine and I can see it with the distributor off the engine. Let's call it an ALIGNMENT problem.

To my understanding there needs to be an alignment, or matching, inside the distributor so that when the camshaft rotates and opens the points, creating the spark, the segment on the cap with each HT lead is above the rotor arm. I believe this is not the case in my new distributor. When the camshaft opens the points, the rotor arm finger is nowhere near where the segment on the cap is. And the distance is such that the spark cannot jump.

For my sins I have studied long and hard how production was organised in a Socialist Command Economy. In those days, meeting the LETTER of the plan was all that counted. Therefore assembling defective distributors is perfectly conceivable as they would count towards meeting the production quota, and their being unusable was irrelevant. I have a feeling I have bought myself an expensive example of such practices. In artillery terms, it would be called a "dud"...

The question is what can be done to put it right. Any number of things can be wrong, the easiest one I can think of being that the shaping of the top of the camshaft that allows the rotor arm to be fitted only one way, was done at the wrong angle.

The other question I have is... suppose I abandon the idea of making it work as it is, can I at least use the casing and rotor arm to convert it to electronic ignition?

Edited May 18, 2010 by iannima

[iannima]

A picture is supposed to be worth a thousand words... so let's see if I make myself clearer:

this is a diagram that I have found on the Russian technical manual. It shows the position of the contacts on the distributor cap leading to the spark plugs. These are all marked with Roman numerals: I; II; III and IV. You will see outlined the shape of the rotor arm that is in the position of firing the first spark plug. At this stage the points should be open to create the spark. I have drawn OVER this a line in red that shows the position of the rotor arm in my distributor when the points are open. As you can see, it is nowhere near where it should be to send a spark to the first spark plug. A similar problem is repeated for all the other three firing positions. This is visible without having the distributor fitted to the engine, and I cannot see how fitting to the engine would make any difference.

 

[Si2]

the rotor arm will not always line up exactly with the cap contact - there needs to be a degree of float so that you can adjust your timing by rotating the distributor around the central shaft. The points are also open for at least 20 degrees - does the rotor move closer or further from the contact through that arc??

I have a very similar distributor on my GAZ, I did the same thing - replaced the radio suppressed version. I am sure it ran well before the engine seized up, but it was a long time ago.

I have seen tow types of distributor advertised for GAZ69, one clockwise and one anticlockwise. If you have a wrong rotation then the rotor is moving away from the contact as the points open, rather than closer...

 

I've also got a rotor arm with a very wide contact face that might help.

 

If the rotor arm is facing nearly the right direction it should be enough to let the spark jump.

 

I'm going to have to go through this whole prcess as I reassemble the engine. What I'd do is set the engine up at TDC on cylinder 1 and then drop the distributor in the engine. Mark on the body where the HT lead contacts on the cap are and put the rotor arm back on. See if you are on a reasonable position and then gently turn the engine over by the starting handle and see how the arm moves.

 

Si

[iannima]

does the rotor move closer or further from the contact through that arc??

Further away from the contacts. The position I have marked in red is basically where the points start opening.

I have seen tow types of distributor advertised for GAZ69, one clockwise and one anticlockwise.

Clockwise is for the Gaz69, Anticlockwise is for the UAZ 469. They look very similar (aside from the shaft) but they are actually very different. I think a UAZ469 distributor would not fit a GAZ engine and I only know of clockwise rotating distributor on tthe GAZ.

See if you are on a reasonable position

We have done that already and we are way out of what might be considered reasonable.

[iannima]

You might think that my trying to change the distributor from the radio screened one is all a whim on my part and that I ought to learn the old saying: "if it is not broken, don't fix it"... well, I am afraid that is not the case...

Today is my last day of freedom, as the exam scripts will pile up in the hundreds as of tomorrow morning. The sun is shining, so I exploited the opportunity and took the Gaz out this morning. I had a bit more of fiddling yesterday and the day before and initial tests in my own street indicated a better acceleration and a happier engine. I chose to put it to the test on a longish run: Durham to Barnard Castle 42.5 Km. or 26.4 Miles. Pleasant fast-ish road with some roundabouts.

I set off around 10 am this morning. I keep a maximum speed of 70-75 Kmh. Very happy all the way there. No problem worth mentioning. At Barnard Castle I refuel at an old fashioned fuelling station with a lovely Land Rover series I in the forecourt. I had always wanted to do that. Obviously I switch the engine off. Having paid, I try and restart. It would not... Try again and again and again it eventually starts. Hot starting is always a problem with these engine but usually you do get your way after a few trials. This was far more recalcitrant than normal. As I make my back towards Durham, I feel the engine not being happy at all: I cannot accelerate in second gear as much as I was able to, in order to reach the dizzy speed of 45 Kmh which enables a smooth-ish transition into so called top gear (third). I decide to play it safe and deviate to Gordon's garage, where I take My Land Rover for everything. (Always use a countryside garage lost in the sticks and used to dealing with farmers' Land Rovers. Gordon has worked on the Gaz before). Unfortunately Gordon is not there at all, probably having taken a vehicle out for MOT. Given that I carry the necessary tools with me, I start fiddling a bit. Trying to increase the advance on the distributor by rotating it a bit, no change. Further fiddling with the carburettor... no change. Engine runs but not smoothly. It is firing on all four but evidently not happy with pops at the exhaust. I switch it off...and then it would NOT restart... :embarrassed: try and try again, it would not restart.

I am not very happy. Gordon is not turning up and I have a dead vehicle on my hands. Fortunately I carry most of the tools I would use at home. I decide to open the distributor. I start poking at the back plate which to my mind is far too slack. I pull on the starter motor lever and cannot see any spark: the points do not seem to be opening. I keep pulling on the advance lever until eventually I see a spark. The points are still barely opening but at least there is a spark. I refit the cap. I try again the starter and the engine fires... :yay:

It still isn't smooth. I try several things with the carburettor, but I do not think it is the culprit. Basically rotating the distributor changes NOTHING as to my mind the back plate stays where it is regardless of what I do. Eventually after much fiddling I manage to get to the state where I can limp home, as Gordon is obviously not going to turn up any time soon. I cannot reach 45 Kmh in second any more. At most 40. Once on the flat, and in third I do manage to get a reasonable speed of 65 Kmh (everything is relative). With rosary in hand... I drive the 30 odd Km back to Durham, doing the occasional hills at 35-38 Kmh :yawn:

On the positive side: I, a hopeless academic, have managed to get a dead engine to restart, and have made it home with my own legs...

On the negative side... I don't know where to start...:banghead:

This afternoon/evening I am going to try fitting another radio screened DDR distributor to see if I can get any improvement.

But this story tells me that my trying to change the distributor is not madness on my part...

Edited May 18, 2010 by iannima

[Si2]

have you checked that all your valves are free??!!

 

Turning the dizzy body will move the points in relation to the shaft lobes, so advances or retards your ignition point.

 

UAZ 469 rotates the other way - that's probably where I have got the contra-rotating dizzy from - sometimes I see parts advertised as fitting both GAZ69 and UAZ 469. that doesn't seem to be the case...I have no 469 experience though.

 

It's a tough one - it's all so simple in theory, but so complex in nuts and bolts..

 

It does sound as is you have an intermittent problem though - if you started out OK and then had issues later. Heat normally affects fuel not spark.

 

Your talk of an electronic points module sounds good - I once had an MG midget and fitting an electronic ignition module made one hell of a difference!

Si

[iannima]

Well yes the valves are free. They were ground when we took the head off in September, and reset and everything. And in any case a stuck valve would manifest itself in a number of ways and not intermittently and repeatedly. I took the vehicle out for a short ride on Sunday and I had a very similar problem to yesterday's: it sounds fine for a while then it hits a bump or something and it is not fine any more, as the timing is not what it should be. I get it home, leave for a bit, try a bit of this and that, and then it appears to have sorted itself out but that is only a ruse...

I am afraid the MAIN culprit is really the distributor and has nearly ALWAYS been... but my attempts at getting rid of it so far have failed...

[iannima]

Your talk of an electronic points module sounds good - I once had an MG midget and fitting an electronic ignition module made one hell of a difference!

Si

Yes that's where I am going too... but it does come at a price: £295 + VAT = £346 and of course the price of the Russian distributor from Bulgaria which was €120 + postage.

In January I had asked for a quote to do a completely new system for the radio screened one and it came to nearly £500. At the time I thought that was too much but it might have been better that way...

Still... if that is the price I have to pay for not being stranded at every beck and call, or always returning to the garage in a condition of near-emergency...

P.S.

Before you suggest it... electronic ignition systems are easily available for the UAZ 469 in Germany for €100, but NONE of those will work on the Gaz and I have asked around and have had confirmation that there are NO ready-made electronic ignition systems for the Gaz on the continent.

[Si2]

can you not just fit a hall affect ingition module??

There's on called an Aldon ignitor - you may need to measure up to find the mosr suitable one - but this is basically a block that replaces the points and a magnetic collar that drops over your cam lobes..

They are over £100, but you may be able to get a uxed one and just modify the points bit base to get it to fit - the magentic olccar is the one tricky bit - but I guess that depends purely on the dimensions of your cam lobes.

 

Si

[iannima]

Thank you for the tip. I must confess I would not know myself how to do that kind of job, nor do I know anybody who could do it for me. If it were 50 quid, I would give it a go, but for over £100 and given the luck that I have had, so far, I am reluctant to risk it. For the price I have been quoted, I would send the distributor to them, and they will do everything except the actual fitting on the engine. I have not decided yet. The first priority is to get the engine to fire again on another radio screened DDR distributor whose back plate seems in better conditions.