DaveL82

Thought this might be a place to see if anyone can help resolve a problem I might be having with a GM points distributor.

Took the cap and rotor off and notice that while the main shaft play seems OK the plate that has the points can lobe and the arm for the cap to bolt to moves up and down about a 1/16 of an inch. Found that when its all the way down the rotor bottoms out on the main distributor shaft. If I install the screws in the cap it pulls the cam plate up. Is this normal? I would have thought this could impact movement of cap and weights needed for mechanical advance.

Is there a washer or shim that should go under the points can shaft (note distributor main shaft play seems OK)?

Dave

0Willcox Corvette

The base plate height is controlled by where the upper bushing is seated in the distributor. If the bushing is too high then excess play can exist between the plate and the bottom of the distributor. If you look at the upper bushing there is a groove cut in it that has a snap ring. This is what keeps the base plate from coming off the bushing.

It sounds to me as if the upper bushing might be a bit high.

You can test the play in the upper shaft with a simple swell meter. If you rev up the engine and the dwell changes then the upper bushing is wore out.

DaveL82

Thanks and I'll look to see if there is an issue with one of the bushings.

Dave

redvetracr

you would have to pull the distributor and the mainshaft to check but the clip holding the points plate on might be missing and while your at it check the lower bushing, thats the one I find worn most of the time

0Willcox Corvette

Yes indeed, that thought that the clip might be missing never breached my mind until Redvetracr posted...

plaidside

Here are some pics to show you what they are talking about.
I wrote an article on rebuilding a distributor for the SACC magazine, if you want a PDF copy send me your email address.
Joe