I'm trying to replace the old distributor in my 1971 500F with a brand new 123 Ignition, but there's a problem. The old distributor is stuck. I've removed the clamping nut, but the case won't budge. So far I've tried spraying with WD40, tapping it with a rubber hammer, and twisting/rocking it with just my hands, but it just won't budge. Other forums suggest using carb cleaner as a solvent to loosen the bond. I'll pick some up tomorrow and try that.
I don't see a gasket there so I suppose it's just corrosion or old coked oil holding it together?
Does anybody have any suggestions before I start applying more force?

ronstox said:

I'm trying to replace the old distributor in my 1971 500F with a brand new 123 Ignition, but there's a problem. The old distributor is stuck. I've removed the clamping nut, but the case won't budge. So far I've tried spraying with WD40, tapping it with a rubber hammer, and twisting/rocking it with just my hands, but it just won't budge. Other forums suggest using carb cleaner as a solvent to loosen the bond. I'll pick some up tomorrow and try that.
I don't see a gasket there so I suppose it's just corrosion or old coked oil holding it together?
Does anybody have any suggestions before I start applying more force?

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Hi Ron, if you have the clamp removed can you turn the body of the distributor in the crankcase by hand?? There should not be anything holding the unit in the crankcase?? Check that the camshaft is fully located into the crankcase and not jamming the distributor on the drive gears, also check that you can turn the camshaft, they should not jam together!!!

Ian.

So, the engine is still in the car, the clamp is removed, but I cannot turn the body of the distributor. Not even a tiny bit.
The engine was running just before I started on the distributor. I am able to turn the crankshaft by hand and watch the rotor turn, so I'm confident that there is no jamming between the distributor and the drive gears inside the crankcase.
I've got the channel lock pliers out and ready to go, but I'm still hoping there is a better way.

Hi,
WD40 or Carb cleaner are not the best release agents. Thry PlusGas or for a DIY version a 50/50 mixture of acetone and automatic transmission fluid. A bit of gentle heat ( a hot air paint stripper on low is good) between applications can help penetration and "cracking"the corrosion, but try removing the distributor cold. Aluminium expands more than iron so the distributor will be tighter wihen hot.


Robert G8RPI.

ronstox said:

Does anybody have any suggestions before I start applying more force?

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If you have the original 110F engine fitted with the original-type distributor, then it is a two-part item. You might first be able to remove the main body by wiggling with the timing clamp nut removed.
I had this problem when my engine hadn't moved for 40 years. I ended up tapping it very hard from inside the crankcase with the sump off and camshaft removed, and even then it was very difficult and I managed to break the pin holding on the distributor gear. Breakage is less of a problem for you if you have the 123 item already. I would heat the base of the distributor as quickly and intensely as possible and then with an extinguisher handy, quench it with penetrating-oil (not WD-40). You will need to grip it with some sort of tool to try for movement. As soon as you feel anything, spray it again with oil and try again. Re-apply oil every time you achieve more rotation and I'm sure it will come out eventually.

Thanks for the advice. I got some Liquid Wrench penetrating fluid and my hot air gun is ready to go, but I'm concerned that the heating and quenching cycle may lead to cracking the crankcase. It's there a real risk of that?

ronstox said:

Thanks for the advice. I got some Liquid Wrench penetrating fluid and my hot air gun is ready to go, but I'm concerned that the heating and quenching cycle may lead to cracking the crankcase. It's there a real risk of that?

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It didn't on mine but if you're worried maybe you should simply try to move it whilst hot. I would be doing it quickly and try to direct heat either at the distributor base or the crankcase in the hope that you get some microscopic differential movement.

Thanks for the advice. I got some Liquid Wrench penetrating fluid and my hot air gun is ready to go, but I'm concerned that the heating and quenching cycle may lead to cracking the crankcase. It's there a real risk of that?

Hot air gun is ok to use.

I just came across the image of the base of the distributor after I had removed it; no help to you but maybe inspiration?

Looking at it makes me realise hat you won't get much wiggle because of the clamping stud. Tricky, but could you get that stud out first? Even that would reduce the forces keeping the distributor unmovable.

KNO_6883 by Peter Thompson, on Flickr

if desperate follow my advice to Ian on removing his early front pulley...
a big hammer and bash the bejeebers out of it...
The feeling of satisfaction will be so good...


I actually have a complete modern 500 engine I can sell you..

Thanks for everybody's advice on their favorite methods. In the end, I invented my own. I just kept spraying with Liquid Wrench, and trapping on the lug bit that the clamping nut goes through with a small wooden mallet. First one way, then the opposite direction. I did this every day before & after work for 10 minutes. The hole in the lug is larger than the stud by about 1mm. After about a week of this, I noticed movement of distributor from one extent of the lug-hole to the other. Once I got this far, I tied some webbing around the distributor body and with a small winch attached to a roof joist, applied a constant upward pull on the distro. Now, I went back to tapping the lug back and forth and in just a few minutes, it was out. Whew. Not hard, but it does take some time.

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