Dome Distributor Disassembly

[JAKEFORD]

I am trying to take apart a Dome type distributor from a 1940 or 41 engine. The drive assembly is stuck in the aluminum housing. I have soaked it with PB Blaster and others to no avail. My next step is to soak the complete unit in diesel fuel in an effort to free it from the aluminum. What about some heat on the aluminum to expand it?

BTW all snap rings and retainers have been removed.

Does anyone have any suggestions?

Thanks

[BUBBAS IGNITION]

We put the drive tang in a vise , spray with JB Blaster and heat the case with a small torch. Carefully hammer the case of leaving the works in the vise . Some are a bear to get loose.....but they will come off ....

[JAKEFORD]

I put the tang in a vice as you suggested and then used a 3/8x1x3 inch bar and tapped the edges. No heat was applied and the insert started to come out. A bit more tapping and it was apart. The PB Blaster had penetrated the rust and helped a lot.
A lot of corrosion. Both breaker springs were broken on the outer leaf and the weights are frozen but now it can be worked on.

Thanks for the idea of putting the tang in a vice.

This was a flea market find I picked up for a dollar about 5 years ago. Now I need to find an engine for it!

[JAKEFORD]

I have all parts clean and am reassembling my distributor but I have a question.

The breaker plate is held in position to the cast collar by a large spring ring. When the breaker plate is in position without the spring, it rotates freely in its groove but when the spring is installed and in the spring grooves it becomes very hard to move. I need to use a screwdriver on the timing tang to move it and the spring rotates with the breaker plate.

The spring was bent in a skewed fashion and I staightened it thinking there is probably too much side pressure but it does the same thing after.

Is this normal behavior? The timing adjustment will probably need a light tap to move the plate.

[BUBBAS IGNITION]

Yes sometimes a light tap with hammer is required to move timing adjustment.....
A grinder wire brush on the spring clip and some lube will help sometimes...

[JAKEFORD]

Sponsored Links (Register now to hide all advertisements)

I polished the ring and the edges of the breaker plate with 320 grit. No sharp edges or bumps. Made sure the groves were clean and with a light oil film the plate is snug but can be moved by hand.

On the coil there is the HV carbon brush which contacts the center of the rotor and there is a LV spring connection to the common point of the ignition points. As you move the plate from max advance to max retard the connection point moves around. Is there enough allowance in the spring so you don't lose contact or the spring leaves the button seat?

[BUBBAS IGNITION]

Originally Posted by JAKEFORD

I polished the ring and the edges of the breaker plate with 320 grit. No sharp edges or bumps. Made sure the groves were clean and with a light oil film the plate is snug but can be moved by hand.

On the coil there is the HV carbon brush which contacts the center of the rotor and there is a LV spring connection to the common point of the ignition points. As you move the plate from max advance to max retard the connection point moves around. Is there enough allowance in the spring so you don't lose contact or the spring leaves the button seat?

Yes been that way for quite a few years...1932-1941

[JAKEFORD]

Went through my junk box today and found an original Ford coil for my Dome Distributor and a set of brand new NOS ponts. The coil seems to check out with my ohmeter so may be OK. But its missing the carbon brush that contacts the rotor. The spring is still in the hole only no brush.

Does anyone know where I can purchase a brush?

Also found, from my flathead days, a distributor timing fixture that I intend to use to set this thing up. This fixture was old when I got it around 40 years ago but is still in pristine condition. The old engine tricks are starting to come back the more I work on this distributor.

[JAKEFORD]

BTW the price written on the points box was 1.29. Made in the USA and brand new.

[G.M.]

Originally Posted by JAKEFORD

Went through my junk box today and found an original Ford coil for my Dome Distributor and a set of brand new NOS ponts. The coil seems to check out with my ohmeter so may be OK. But its missing the carbon brush that contacts the rotor. The spring is still in the hole only no brush.

Does anyone know where I can purchase a brush?

Also found, from my flathead days, a distributor timing fixture that I intend to use to set this thing up. This fixture was old when I got it around 40 years ago but is still in pristine condition. The old engine tricks are starting to come back the more I work on this distributor.

Jake the new coil you found will have the same problems as one that was used for 60 years. The insulation back in the days these coils were made
was no were near as good as what is available today. On a warm day when the engine gets hot 99.5% of all old Ford coils start to break down. When trying to restart, the engine won't start until you wait about 1/2 hour for it to cool. Skip in Florida rebuilds the coils using modern insulated wire and materials that are not effected by the heat. G.M.

[JAKEFORD]

I found my brush and spring assembly at the Early Ford Store out in California. Very reasonably priced.

I had experience with an old 1938 1 1/2 ton truck, a 1940 one ton and a 1941 1/2 ton. This was back in the day and the trucks at the time were about 25 years old. I never had any coil problems with the ignition cutting out when hot. I had vapor lock and lots of it but never any ignition problems. These were farm trucks and worked hard but always started when cold or hot.

I wonder if the problem today with original coils is too much primary current and electrical overheating.