Prestolite dual point distributor swath (RB) too long

[AR67GTX]

Replacing the electronic distributor in my Satellite Hemi with a dual point I got from a friend who I rebuilt it for a couple of years ago. He never got around to running it. It will not fully seat in my engine and when I measure the shaft length to mount surface, it measures 4-1/8 inch long instead of 4”. From the tag I remember it’s a 67 CAP Hemi distributor. I was using a metal seal under it but it isn’t close to sealing at all. It appeared to be a pretty nice, unmolested distributor when I rebuilt it. The electronic distributor I removed measured the correct 4” shaft length.

Any idea what’s going on here?

 

[RJRENTON]

Replacing the electronic distributor in my Satellite Hemi with a dual point I got from a friend who I rebuilt it for a couple of years ago. He never got around to running it. It will not fully seat in my engine and when I measure the shaft length to mount surface, it measures 4-1/8 inch long instead of 4”. From the tag I remember it’s a 67 CAP Hemi distributor. I was using a metal seal under it but it isn’t close to sealing at all. It appeared to be a pretty nice, unmolested distributor when I rebuilt it. The electronic distributor I removed measured the correct 4” shaft length.
Any idea what’s going on here?

Have you measured the drive key length? This "key" is the cut back area at the end of the shaft. This key fits into the distributor dtive/oil pump gear. It is possible that the flanks of the key were not machined the additional 1/8" or perhaps the bushing under the drive gear was not pressed in the 1/8" amount causing the interference. Could you have an O-ring groove machined in the body casting flange to fit an O-ring as the copper crush washer is very prone to leak. BTW...do you know the distributors tag number....if known, I could tell you the mechanical advance numbers.
BOB RENTON

 

[Fran Blacker]

Did he put a new distributor shaft in? I have a NOS distributor shaft there is no hole drill in it for the roll pin. If it wasn't shimmed up inside it would be a problem. That said 1/8" is a lot to be a shim problem.

 

[Fran Blacker]

Assume you had a distributor in the engine? Compare old and new.

 

[AR67GTX]

Need to correct something I said in my first post. The old distributor shaft also measures 4-1/8" long too - must have fat fingered my caliper in to big a hurry. Here is a photo of the two side by side. Seems strange though as most of the specifications I find say it should be 4" for a RB shaft.

It does have a much shorter drive tang on it than the old one but I measured the depth of the slot in the oil pump drive from the block machined seat and got 4-3/16" and top of bushing was 3-29/32" so that shouldn't be an issue. I lightly filed the shoulder on the distributor to clean it up and it seems to fit in the block OK and rotate. The tang does go into the oil pump drive slot and the slot is only about 9/32" deep so length of tang should not be much of an issue. I may just have got in too big a rush and need to work on it some more. I can't see any reason it shouldn't seat and seal.

 

[AR67GTX]

I think I’m going to guilty of crying wolf on this issue. The machined seat on the bock is nearly flush with the top of the block casting on the side facing the coil mount which is right where you naturally look to see if it’s seated. I was kind of alarmed when seating the distributor that the metal gasket was still visible slightly above the block edge - I hadn’t noticed how shallow the machined seat was. After installing the hold down it seated the distributor base down firmly and everything looks fine/normal. I got in too big of a hurry and was rushing it.