'57 Century Distributor Vertical Play

[autonut]

I have my distributor out which is not very accessible and wondering about the end play.  I have enclosed a picture.  There is about 0.200" clearance which seems like a lot. There is so much play that if I lift the point assembly up when the gear is down the point assy will actually clear the vacuum advance solenoid pin which to me does not seem like a good idea. I am thinking that perhaps the distributor was mfg with some vertical play to adapt to the engine internals. But wondering how much play was normal? Have been having trouble with point gap.  Hate to put back in if something is not quite right. I am wondering if gravity will always keep the cam lobe down or with higher rpm will it rise? Does anyone have a distributor out to look at it and compare?

Lee

[Bhigdog]

Sum Ting Wong. I have an old used one and it has about .050 play...................Bob

[High Desert]

I think your drive gear pin is sheared. Have you tried holding the top portion of the rotor and twisting the gear portion? It may come off.

[old-tank]

END PLAY ...some is normal in 57

[Bhigdog]

15 minutes ago, old-tank said:

END PLAY ...some is normal in 57

 

That agrees with what I see in my spare 57 dist..........Bob

[autonut]

Would one of you be willing to sell that spare '57 distributor you have? If it is a part # 1110870 which I suspect it is, I would really be interested. Mine is messed up and for some reason, the points will not stay in adjustment.  It is sooo difficult to take it in and out to try to find out what is wrong with it that I have pretty much given up on it.

Lee

[NTX5467]

There needs to be SOME end play, but not quite as much as you have.  There are washers/shims to adjust it, but usually the rebuilders have them.  Might be common with other ACDelco distributors used in other GM vehicles, too?  There's also two bushings in the distributor casting which are the "bearings" for the distributor shaft.  There is a spec for "play" there, too.  The distributors are relatively easy to take apart, but some solvent might be needed to remove the build-up of varnish on the distributor shaft itself so the shaft will then slice out when you knock the roll pin out of the distributor gear.  Clean it up in a parts washer,

 

The points' adjustment issue could be due to the distributor housing bushing wear (possibly at the bottom), not to mention the vertical end play of the shaft.  When the cam turns, it'll try to force the gear/shaft either upward or downward, depending on which direction things turn.  No reason why a competent distributor rebuilder can't possibly rebuild yours, but then finding one of those people might be worse than hens' teeth.

 

Knowing which model years of Nail Head's that use the same distributor body might be important.  Even if it's not the same stamp number, you can swap the weights and springs into the "new" distributor.  For that matter, you could purchase a rebuilt distributor and swap the advance weights and springs from your current distributor into the rebuild model.

 

NTX5467

[Bhigdog]

On ‎5‎/‎13‎/‎2016 at 11:45 AM, High Desert said:

I think your drive gear pin is sheared. Have you tried holding the top portion of the rotor and twisting the gear portion? It may come off.

 

As unlikely this sounds I think it's possible. The positive test is to measure the distance from the lip of the gear counter bore to the oil pump drive tang. That should measure .170 or just a bit less than 3/16". If it's more then the gear pin sheared. If it measures OK than either someone put the wrong gear on the shaft or there is major wearing top side which is very very unlikely. If the distance measures .170 or so let me know and I'll check the over all length of the proper gear for you to compare...............Bob

[Barney Eaton]

Some end play is required just for expansion of the parts when they get hot.   You probably can buy shims somewhere, but I always made my own.

Notice that the gear is not straight...if you make a mark at the top of the gear, then push it up, you will notice that the shaft will turn a few degrees as it moves up and down, this can change your timing a few degrees.

It is best to shim it to reduce the possibility for timing change.

[Airy Cat]

I converted all of my Buicks to Pertronix electronic ignition.  No points, no condenser, no problems for the last 20 years.

[60FlatTop]

I only use original old stock points or Echlin points from NAPA. The newer stuff in Standard boxes is inferior. If your dwell is stable I wouldn't worry about end play.

 

 

Edited May 15, 2016 by 60FlatTop (see edit history)

[drhach]

Time for a thread resurrection. I'm having the exact same issue on my 62. I want to install a Pertronix unit while I have the distributor out. Pertronix calls for .010-.060 at either end of the play region in the distributor. However, I have about .2 as well. So, there's no way I'll get that. I ordered some shims, but I', concerned about over shimming it and then have an oil pump issue. Any thoughts? The engine block is at the machinist right now getting redone. So I can't put the distributor in to check.