Distributor.

May 30th, 2014

Today I finally got around to seam sealing the bottom of the body. Well, I’ve done half of it. I didn’t want to work upside down so I did one since today and will flip the body over and do the other tomorrow.

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I use Sikaflex-221 sealer which is a proper automotive sealer. I wipe everything down with wax and grease remover then I use tape to mask around the sealer then pull the tape off before the sealer is cured. A little thinners on a  finger allows you to smooth the sealer down. If you’re careful it doesn’t go on the tape. You can also see above some of the pop rivets just used where the aluminium can’t wrap all the way around the tubes. These are all under the car so hidden.

I also did a little more cleaning on the dynamo and the distributor. Joss bought over some more old dynamos I can strip so I can build one (hopefully two) serviceable ones from the parts. I definitely need a new drive gear. On mine the teeth are worn to sharp edges.

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The teeth should be like the one on the right.

I also started stripping the distributor. It’s pretty knackered. There was  lots of axial movement on the shaft. Not a lot of radial movement though so the shaft/bush must be good. The radial movement is what can upset timing on worn distributors. Fitting electronic ignition will get around this as the electronic switching isn’t affected by the shaft wobbling about a little unlike switching using mechanical points. I did that on my MGB and it works well but I don’t want to do that on my Austin, I’d rather things be correct.

To totally strip the distributor you have to remove the drive gear. This is held on with a pin. To remove the pin I first filed the peened over edges on the original pin then I pressed it out in the vice using a socket on one side (to make a space for the pin to slide into) and a little round shaft on the other to push the pin out. I made the little shaft from an old drill bit. You need something strong. I broke the bit in the vice so only the shank remained and ground the end square on the bench grinder.

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I also had to file the end of the shaft, which was slightly peened over, so the shaft would pull through the gear and the bush in the body. With the shaft removed I could see the wear on the base plate and the little advance weight toggles.

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The shaft is attached to the base plate on which the weights ride. The weights are pivoted at one end on pins fixed to the base plate. There is a pin on the other end of the weight that the toggles fit over. A spring goes from the toggle to a pin on the pivot end of the weight. The pin the toggle fits over goes right though the weight and fits into a hole in the base plate. The hole limits the advance by limiting the movement of the pin.

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The part the rotor attaches to is a separate piece that slides over the end of the shaft and is held by a screw. A plate on this short shaft has two pins on it which ride in the second set of holes in the little toggles. As the dizzy spins the weights fly outwards. This moves the toggles which in turn twists the short end shaft to give the mechanical advance.

On my distributor there are several problems. One, I don’t think it’s the right one for an Austin 7. The base plate is marked 10 degrees (10 degrees on the dizzy means 20 degrees total spark advance) but a Ruby engine should have 8 degrees on the distributor. Another problem is that the plate attached to the short shaft is 1. bent and 2. not firmly attached.

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The last problem is the holes in the toggles are work out. You can see in the pictures above that they don’t sit flat at all.

So all this means I don’t have a good distributor. I can try to repair this one. I imagine I’d have to straighten then silver solder (or peen?) the plate above. I guess you could weld up then redrill the toggle holes. And the end movement on the shaft can be taken out with shims (there were shims there already just not enough). The 10 degree base plate isn’t a bad thing necessarily as a bit more advance is good on a tuned engine but then again I’ll have a blower in which case I think you need to retard more when you’re running boost. You can fill in and refill the holes in the base plate to adjust the maximum centrifugal advance. There is no vacuum advance on an A7. I don’t mind trying to rebuild something which is too knackered to use as is as I don’t have anything to lose but time (but I gain experience).

The UK people would probably say just send the distributor to the distributor doctor for rebuilding but I imagine that is quite expensive, more so for me being on this side of the world.

Another option is fitting a modern Bosch distributor. You can apparently use the Bosch 009 which is fitted to VW beetles usually. I believe you need to machine the housing a bit so the drive gear will fit and also drill the cross hole to pin the drive gear onto the shaft. You also need to limit the advance but fitting an extra stop to a little peg inside them. These distributors can be bought ready to fit to an A7 in the UK for about 90 quid from AustinRepro (which actually seems very reasonable).

 

The Bosch 009 distributors are available locally but I don’t think they are real Bosch ones these days. They are cheap copies so the quality is probably questionable. They all seem to be advertised as Bosch 009 type, not actual Bosch so I don’t really want one of them.

The other alternative is to find a less worn Austin one. Perhaps the spares department has some?

Will have to give that some though. Given I want a good, solid engine I am tempted to just get the UK Bosch one that just fits. I am already running a non standard fuel pump and will have a (plastic!) water pump and it is a well known Austin mod (from an Austin supplier). Can stick to strict originality on my next car!

 

 

 

6 Responses to “Distributor.”

  1. Nigel Hamlin Wright Says:

    Hello Simon,
    A couple of things; it might be worth putting the body on the scales whilst it’s off the car – just for interests sake and, I’ve had to blank off part of the radiator on my Austin because the water pump is too efficient (I’m also running a modern core). In the summer I’m getting a reading of about 160F which is still a bit cool I’m told but, who knows? Perhaps you could preempt any over-cooling problems by turning up a set of restrictors of various sizes to put in the pump line. A separate switch is also handy. Great work.
    Nigel

  2. admin Says:

    I did think since the water pump is electric it would be silly not to fit a switch. Not sure what core I will be running yet but I imagine it will have to be a modern one. Building a new engine it would be silly to then put an old core on it. I have weighed the body before when it was in pieces and I think from memory it was 57kg. I’ll re-weigh it tomorrow.

  3. Jack Says:

    Hi,
    I am UK based and use Bosch generic dizzies on my two Austins. I don’t think the ones sold here are actually Bosch made anymore, they are probably made in China or Mexico. My thoughts are that unlike the Lucas originals, they are at least in good condition and since most Austins’ cover small mileages anyway are likely to give good service for many years(having said that my RP covered 11,000 miles last year and the electrics were faultless) It is my small experience that to be able to eliminate one source of error that can produce significant variations in running is a great benefit and leaves one more time to concentrate on the things which cannot be replaced and need compensating tricks to overcome. Good luck with the project I am enjoying the ongoing tale and your telling of it.

  4. Renaud in Brittany Says:

    Hi everybody,
    Good work as usual Simon. Always a pleasure to follow your progress.
    Why not a thermostat in a water hose if there’s a risk of underheating?

  5. admin Says:

    Or just drive it fast so it gets hot quickly! I’ll see how it goes. I won’t be running a fan on it.

    I’ve been in touch with the repro Austin guys and they can send to NZ. I’ll work out cheaper for me to get one straight from them than trying to find a Bosch here then having to modify it and find a drive gear and so on.

  6. dave Says:

    Bought a distributer from Austin Repro listed as Bosch but actually it isn’t, condenser failed after about a year and only a few hundred miles and found the brush in the cap is not touching the rotor, just sparking across, they offered me a different cap at £15 no offer to replace the condenser, don’t feel I should have to pay extra to put right a fault.

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