VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Oil pump thrust washer for distributor

I have received some help from people here about the oil pump thrust washer and where to purchase one as there is not one in my engine. I understand this washer's purpose is to hold up the shaft of the distributor so the weight plate doesn't rub on the bottom of the distributor's interior housing.
What I do notice when putting my distributor in now without the washer is the weight plate w/rotor rises slightly when the distributor is fully seated in the block. If the washer is normally intended to do this then why is mine lifting without it? Is the gear resting on the oil pump's top. Is the slotted part of the shaft itself bottoming in the oil pump key? If the shaft is already lifting as is without the washer wouldn't the washer make the distributor stand too proud possibly causing an issue. Sorry for all the questions but that's why I'm here and the members with experience have probably seen this issue before.
Thanks, Ted

Mine does exactly the same thing. When I seat the distributor the weight plate rises off the distributor. I also don't have a thrust washer for the distributor.

The best answer I can give you is that Chevrolet Engineers designed the entire mechanism and the spacer to put the distributor components in the correct position to function properly for the life of the car. I figure that unless there is some compelling reason or new innovation that renders that original engineered concept invalid that I will stay with the design.
Ron

Based upon the design of the gear on the Distributor and the fact that it is called a THRUST washer, I would assume that its true intention by design is to absorb the THRUST of the distributor shaft (end of Distributor Gear) when gear on the Distributor is initially engaged by the Gear on the Cam Shaft. With this in thought it seems that the THRUST would be DOWNWARDS, therefor slamming and forcing the distributor shaft down into the casing of the Oil Pump.

So the Thrust washer serves a few purposes, one to absorb the impart of the distributor hitting the pump housing, and serving as a wear plate since the housing does NOT turn and the shaft does. bottom of the Distributor Gear would RIDE on the washer. Lot cheaper and easier to replace a washer when it gets worn out or eaten up vs FINDING a new oil pump. Could even open up the hole and distributor slowly works it was lower and lower into the oil pump housing. Also would seem that the thrust washer in absorbing some of the impact it would help keep the oil pump in position and not loosening up or slowly working itself down. Yes the set screw holds the oil pump in place, but a constant thrust and slamming on the oil pump can elongate the hole/ point the set screw sets in on the oil pump housing.

Sorry Just my view of Thrust Washer & its Intent... We use Thrust Washers here for those 2 reasons in our Products !!

I believe is was intended as a wear surface.
In the parts book it is described as washer, oil pump thrust. Is in group 1.666. The 1929-1936 is part number 346732, 1/2" ID and 1" OD.
For 1937-1955 is part # 838472, 1/2" ID and 3/4 OD.
In the 1959 parts book it is listed as use only up to 1955.
The oil pump/distributor set-up is the same up until 1962 so why is no washer listerd for those years?
I found a rather thin general washer of the correct demensions for use in my 1950.

I don't want people to think I wasn't going to use the washer. I was just stating that my distributor rises up when putting it in and if the washer would cause a problem by pushing up too far.
I would suspect the best thing to do would be to insert the distributor in the bore with the washer and to have the manual advance clamp loose. Once the distributor is fully seated on the washer, then push the clamp down to the top of the block. Put in the shoulder screw and spring, then tighten the clamp around the distributor. Does that installation procedure sound correct? I believe this way it would prevent any upward pressure on the gear into the bottom of the distributor housing.

The clamp around the distributor serves 2 purposes, to hold the assembly down in proper place so it does not move excessively up and down (except what is permitted by the afixing spring), and to fine adjust the timing. It clamps into a groove I recall and so really has no advantage in sorting the concern you have. A previous post (Bill B's advice) dealt with the issue of minimilizing end play for the Dist shaft (max 15 thou?), and thus avoiding several issues outlined above, i.e. wear on dist housing/case, wear on gearing, etc. So install proper washer and as previous poster suggests, let's not try to second guess the original designers. It is important that the Dist gear not be moving up and down as it turns at 1000 rpm against the cam, and the proper washer/spacer will ensure this.

Here's the previous discussion.

CLICK HERE

Thank you for that link,
Ted