Pertronix Electronic ignition

[GrahamFountain]

I had a more extreme, but perhaps similar, issue a little while back. That was after the Sprint had been stood for several months.

It would start in the morning, no problems, then run okay for a few miles before starting to misfire worse and worse, and behaving like it was running out of fuel, though the tank was near full. Taking the fuel cap off made no difference, but after just leaving it for a while it would seem to start pumping fuel again. But, it would only run for a few hundred yrds before appearing to run out of fuel again. The battery went flat before I got very far like that, and I had to get the AA tow me home.

Leaving it overnight and charging the battery, it ran on tickover for ages, but under load, it only ran for a short distance before repeating the whole process.

Replaced the mechanical pump, and left it again, and it seemed to be pumping fuel when cranked, but it still wouldn't go far before dying yet again.

Graham

[soe8m]

What carbs are on the engine?

Jeroen

[Carledo]

I had a more extreme, but perhaps similar, issue a little while back. That was after the Sprint had been stood for several months.

It would start in the morning, no problems, then run okay for a few miles before starting to misfire worse and worse, and behaving like it was running out of fuel, though the tank was near full. Taking the fuel cap off made no difference, but after just leaving it for a while it would seem to start pumping fuel again. But, it would only run for a few hundred yrds before appearing to run out of fuel again. The battery went flat before I got very far like that, and I had to get the AA tow me home.

Leaving it overnight and charging the battery, it ran on tickover for ages, but under load, it only ran for a short distance before repeating the whole process.

Replaced the mechanical pump, and left it again, and it seemed to be pumping fuel when cranked, but it still wouldn't go far before dying yet again.

Graham

So what fixed it????????

Sounds like condenser failure to me!

Steve

[GrahamFountain]

No, the condenser, actually a bad batch of them, was the problem of a couple of years back - still running on one from Martin Jay, the Distributor Doctor.

This one was a nearly complete blockage of the outlet from the fuel tank. It appears to me that the car was running on what was in the feed pipe underneath, which would empty, and then refill really slowly.

Got it to clear just with reverse flow from an electric pump - I couldn't blow manfully enough to clear the pipe, and I sure as hell weren't going to suck. It's been fine since. The pump is still in the boot, and the first spare distributor with a tested good condenser (it still feels so thermionic valve wireless era to write that and not capacitor).

Graham

[Carledo]

This one was a nearly complete blockage of the outlet from the fuel tank. It appears to me that the car was running on what was in the feed pipe underneath, which would empty, and then refill really slowly.

Graham

This is actually so common, especially on cars that that have spent time stood still (I see a lot of these with all the re-commissions I do) that I have a special tool for the job, that old radio ariel standby, an old fashioned wire coat hanger, opened up and straightened!

When i'm recomissioning a fuel system, the first thing I do is rod this out, the amount of time it takes to clear it is a good guide to the internal condition of the tank!

Steve

[Graham.Fountain]

I wouldn't care so much, but it was a replacement tank not that long ago - I suppose it must be 2 years, maybe 3. And I did check it seemed clean inside when it arrived. But I admit, I spent a lot more time hammeriting the outside areas of it, where the old one had rotted through, than looking inside. And it's a locking cap on it, so even if I thought someone might do something to adulterate the fuel, I don't see how they could.

Graham

[soe8m]

It's still guessing as the type of carbs are unknown. It can be an engine with webers. More important, are the carsb re-used form the old engine to the new and did the problem also moved with these.

The facet and filterking are quality items and don't need to be replaced often. When there's a fuel shortage you should here a facet making more noise as when it's short of fuel. Revving high in 2 and 3 at hill climbs would also show a blockage I guess.

Jeroen

[shaunroche]

It's still guessing as the type of carbs are unknown. It can be an engine with webers....
Jeroen

Hi Jeroen, they are fully rebuilt Dellorto 45's, correctly jetted for the cam.

Since my last post, I replaced the dizzy cap for a red rotor arm and ambassador NOS cap and put a new Facet fuel pump on.

It was back on the dynapac Rolling Road on Thursday where before it blew a spark plug apart, the following was noted...
using a timing light, the dizzy was timed up at idle where the timing was spot on. Pertronix advise around 12°advanced which is what it was set at.

As the revs rose higher and higher, it starts to advance, but then the timing mark wobbles back and fro and then as the revs get above say 5k, it starts to retard, so much so that when it's in top gear it's loosing about 50% of torque...the dizzy has just been rebuilt by distributor doctor so we're wondering if it's something to do with the jack shaft gear being worn?

So, the engine's now out and with 'TrackerJack' where it's getting torn down to see if the spark plug has caused any damage and to inspect the jack shaft gears.

When it comes back I've got a set of fully rebuilt and correctly jetted DCOE 48's to go on it.

After this, the only thing left on the cat from the initial build, will be the fuel cell, the fuel lines and the ignition wiring.

If it's still playing up after that, then I don't know what else to do....



Anyway, here's a picture of it when it wasn't arsing me about at the Goodwood Members' Sprint just for sh it and giggles...

[soe8m]

Movement of the dizzyshaft up and down or the jackshaft moving back and forwards does cause timing issue's but that would only be a few degrees. If it is very much retarding something is also very wrong.

Do you have the vacuum advance fitted? If so, maybe on the wrong take off?

Jeroen

[GrahamFountain]

I've noticed that when the 44D's baseplate has been replaced with a 45D one, the pin that the arm of the vacuum advance fits onto, can be very, very close to the tops of the posts the bob-weights turn on.

The top bit on the main shaft, under the cam, is about 10mm longer on the 45D than the 44D, so the baseplate sits about 10mm higher off the centrifugal advance in that. So there's a lot of room for the vacuum pin and arm in the 45D, and the pin can be that bit longer. This is why the arm in the vacuum advance units on the 44D has an upwards kink in the end to fit on the shorter pin, and the 45D one is flat cos of the longer pin.

So, the 44D baseplates are unobtainable, but new one for a 45D are quite widely available for about £6 each. In which case, if that's been replaced in the rebuild, it's more than a chance a 45D one was used - other than the length of that pin, they do look exactly the same. A couple of the 44Ds I've got had the part the vacuum advance moves ceased tight. So, currently, they have h 45D baseplates in. I've yet to try one of these in the car, not least because I'm debating with myself if I should grind 1 to 1.5mm off that pin first.

That's because, if that pin were to get even brushed by one of the tips of the bob-weight posts when the main shaft is pushed up by the helical drive and when the vacuum unit is advancing the timing, that pin would get knocked anti-clockwise, i.e. with the spin of the shaft, and so retard the ignition at least back to where the vacuum unit allows. Whether that would affects all 4 cylinders or just one or two, I wouldn't care to guess, But I bet it wouldn't be fun.

In the ones I have I can't make them touch by pushing up on the drive shaft, but I've shimmed out all the vertical play on the main shaft, and the gap only looks like 10 or 20 thou or so. I'll see if I can get a picture tomorrow. But even with the flash on, it's a bit dark in there.

Also, someone at Lucas must have decided the 44D needed a shorter pin than the 45D for some reason, and I wonder if this is it.

So it might be worth a look.

Graham

[GrahamFountain]

I couldn't get a picture through the slot the vacuum arm goes through; well, not one worth posting. But here's ones showing the differences between the vacuum pins on a baseplate from a 41655 44D4, an original one from a later 45D, and a new made one for a 45D.





It may not be obvious from those NVG pictures, but the vacuum pin on the new 45D baseplate is about 1mm longer even than the pin on the original 45D plate. I only just got this new made one - I was looking at modifying it to fit in the 41402, where the baseplate wedges in the body, but I got a NOS one for the early 45D that also wedges in before I started along that path - so this is my first proper look at it.

I've had a bit of play with the spares I have to hand and found the following:

The original (NOS) baseplate from an early 45D fits in my 41402 44D4 with some clearance at 0 rpm.
I think there's 20 or 30 thou, but at this point I haven't measured it.

The original baseplate from a later 45D, with two screws that hold it in the body, fits my 41589 44D4 with at least some clearance at 0 rpm.

The later original 45D just catches the bob-weight posts in my 41655 44D4.
It's not enough interference to stop the distributor turning, or for the post to move the points plate at hand turning speeds. But I can hear the posts scrape by the pin, and I suspect it would have an effect at higher rpm. I also know that both of the 41655s I have, have higher posts than either of the 41589s I have. That's from playing with the manual advance mechanism I've been working on off and on for a while.

The new made 45D baseplate (a poor copy of the Lucas original - so doubly damned), has a vacuum pin that is way too long to use in any of my 44D4s.
In the 41655 44D4, the bob-weight posts jam hard against the vacuum pin. I'd be surprised if it stopped the distributor from turning or snapped the pin, but I bet it would bend it, would probably scupper the vacuum advance mechanism, and might continue to catch in some situations.

Graham

[GrahamFountain]

Additional:
If I push down on the points plate of the baseplate from a newer 45D when fitted in my 41655, then the bob-weight post catches well enough to move the points plate round to the limit of its travel before it passes.

So it looks possible that, given a few thou of endfloat on the main shaft in the distributor, the drive might push the bob-weight posts up a bit at revs and make it retard the timing in some interesting ways.

[GrahamFountain]

With a bit of mucking with lighting, I got the picture of the bob-weight post meeting the vacuum pin I wanted. This is the later 45D baseplate in the 41655 44D4:

Graham