When I pulled the distributor from my motor there seemed to be alot of up and down play in the dizzy shaft so I bought a shim kit. I was wondering how much clearance between the installed gear and the shim is enough.

If I place the largest shim on the shaft then fit the gear, it leaves about 2/3 the thickness of a credit card between the shim and the top of the gear, however I read that too much shimming can spell bad news for your oil pump drive and wanted to know how much is too much.

Is it also OK to use more than 1 shim to gain the clearance you are looking for? If i stack the 3 smaller shims it leaves about the full thickness of a credit card between the shim and gear.

Another question I had is when re-installing the distributor gear, the dimple on one side of the gear is suppose to line up with the rotor tip. What is the reason for this and what will happen if you install the gear with the dimple on the opposite side of when you took it off, because when I knocked the roll pin out and removed the gear the dimple was facing AWAY from the rotor tip.

 

You want about .010" of end play. Use as many shims in whatever configuration you need to achieve this.

You don't need to worry so much about the orientation of the gear.

 

So should I use a set of calipers to measure the clearance between the gear and the shim?

 

No, feeler gauge

 

Here are the closest two combinations I could manage:

Big shim alone = about 0.018"
Big shim + one small shim = about 0.08"



EDIT: With the big and little shim combo I can get the 0.10 feeler gauge in the gap but it is a very tight fit.

 

.018" isn't too terrible. What shim set are you using?

 

Mr Gasket 2820.

So you would advise against the .08?


EDIT: I was just able to achieve a comfortable .010 with the big and small washer after discovering the tanged washer had a slight bow in it and tweaking it with 2 pairs of pliers.

 

Not on an aluminum-bodied distributor. .010"-.015" is about ideal.

 

Got it. kinda odd that the .010" feeler gauge slides right in and out between the shim and the tanged washer with no resistance at all but It's a bit of a tight fit between the shim and the gear. Anyways I Inspected the shaft and replaced the pickup, then drove the new roll pin through the gear (After breaking the old one upon removal) so It's all set.

Thanks again Apeiron!

 

FYI- when you put the gear back on there is a dot stamped in one side of it. That dot should point in the same direction as the tip of the rotor points (not 180* opposite).

.018 sounds fine. GM leaves them loosey-goosey from the factory for some reason. When it's running the load of the oil pump and the helical-cut teeth pull down HARD on that gear anyway- not much chance of it flopping around while the motor is actually running.