MTFCA Forum

Hello -

The previous owner of this 1926 Roadster fit it with a distributor and, while out driving one day, the spark linkage came apart under the hood. The linkage arm was found disconnected (I think the nut fell off). Here’s a picture of the linkage pushed back together without a nut

The other end of the rod looks like this:
The problem I’m having is that when I put the linkage back together and put a nut on it, the spark lever cannot make the full range of motion. It stops about halfway and feels like it is binding. When the linkage is disconnected, the spark lever moves up and down smoothly as it should.

Any ideas what’s going on here? Am I missing a part?

Thank you

Chris, Looking at your photos, I see and "intermediate relay" linkage on the driver's side of the engine. I have never seen anything like this. On all of the engines I have ever seen, the spark rod is ONE piece from the spark lever linkage to the timer or distributor. It is bent so that is does NOT contact anything across the front of the engine.

Many members here will be able to give you better input.

Good Luck

Linkage rod may need some bends to clear the Pittman arm and radiator tube.
With the first rod removed, move it, feeling for drag.
One suspect from your pix is the bell crank pivot. Lotta rust & no lube.
The distributor retaining bolt can be to deep into the distributor housing.
Lubricate all moving joints with a little oil regularly.

The linkage worked perfectly before the nut fell off, so I think the bends in the rod are fine. The pivot moves smoothly as well - that’s why this is such a mystery to me.

The pull on the lower rod and the connection point on the bell crank device look almost in line. This will make for a more difficult first motion between the two components. Perhaps this is due to the fact that the connector with the missing nut is loose on the shaft, as evidenced by the locknut not being in contact with the body. If you correct this it may help out with the problem.

Allan from down under.

I loosened the locknut while trying to figure out what was going on and making no headway. Originally, when this problem first surfaced, it was locked down.

That appears to be a older Rader Bosch conversion with the bell-crank assembly - I believe TTP came out with the reverse cut gears thus a single connection rod.

Maybe the linkage went through the top of the lever arm initially? You show it going through the arm from the bottom side up. When it's like that, the linkage will bind on the pitman arm hub.

Hi Chris,
I'm thinking your linkage some how got turned over. This is what my linkage looks like on my Reder distributer. ( please excuse the mess I haven't cleaned it up from the last speedster run) Craig.

Here's a copy of the instructions for a Rader distributor & a photo. I suppose one can mount the bracket either way.

This is great information and thank you for the helpful ideas. It will be a little bit before I can get back to work on the car, but now there are a couple different starting places.

One other idea I’ve had is to start at the other side of the linkage to see if the distributor is somehow jammed. It might be possible since the linkage was loose when the nut connecting it to the spark lever fell off.

The device to which the linkages are attached is meant to convert a pulling action on the lower rod to a pushing action on the top one. Steve and Craig's photos show that when the bottom rod is pulled, the top one is pushed. On your setup, pulling on the bottom rod will achieve very little, as the pulling point is almost at its lowest point, so the pushing motion on the top rod is very limited.
On both their installations, the bottom rod is pulling to the side, whereas on yours it is pulling down. The geometry is wrong. The low point should be further to the frame side of the device.
Either that, or I am not reading the photos correctly.

Allan from down under.

Your bell crank link is on backwards. The long end should be on the bottom end connected to the rod at the steering column. Installed the way you have it gives the distributor too much ring of motion. Up on the spark lever will be too retarded and down too advanced.

Range of motion. Spell check strikes again.