OFIS

hi guys

i take out my distributor and i found that i have only one shim (B) in the gap between the body of distributor and the gear wheel.
the gap looks in my eyes to big and i couldnt find what is the correct space between them. (A in the attached photo).
i found in corvette central part no 727148 kit of shim but with 5 pieces of shims.
http://www.parts123.com/parts123/yb....rt~A2~cadefibG
ill be glad if someone knows what is the proper gap\space (A)
thank you in advance

7t9l82

first off, your gear is upside down.

OFIS

yes you are right..i mistake taking the photo
do you have an answer?

7T1vette

You took out your distributor; and you also took it apart. But, when you put it back together, you installed the drive gear upside-down. Remove it, put gear toward the dist body, re-pin it....then check for clearance. It will likely check differently.

For setting shims, only install the pin far enough to engage the two pieces (so that you can easily remove it again, if shims need changing). I believe the proper amount of clearance is around .002-.005" [.05-.12 mm].

gcusmano74

When you reinstall the gear, the dimple on the side should line up with the electrode on the rotor.

DC3

In previous threads, Lars has recommended end play to be
.005" - .007” for cast iron housings and .010" - .015” for aluminum housings.

DC

7T1vette

OK. Go with Lars' suggestion.

lars

That's correct. That will give you a nice, precise fit. But a little more clearance won't hurt performance if you can't get a shim combo to hit that narrow window. On the cast iron distributors, anything less than .010 is good, but you need to give it .005 or more. The aluminum units need a little more clearance, so if you get it anywhere in the mid-teens you're good.

Use Moroso part number 26140 for the shim kit.

Be sure to put the gear on the right way (it's upside-down in the photo) with the dimple pointing the same direction as the rotor firing tab.

Lars

Sayfoo

Why?
I took mine apart and I don't know if it is like this or not. Don't want to pull it if I don't have to. Seems to run fine now. I guess there is a 50/50 chance it's right?

gcusmano74

If it runs fine now, leave it alone.

Sayfoo

Still intrested about the dimple.

'75

The gear has a dimple near the pin hole, be sure to put the dimple lined up with the rotor contact.

Mike Ward

This is important to make sure the rotor is aligned precisely with the cam gear teeth. If the gear was oriented 180* out, this will change the relationship with the rotor and cam by exactly one half tooth.

The ONLY difference this makes is with the position of the distributor housing when setting timing. Many owners find that they can't set timing without the housing hitting the intake manifold or coil bracket.

Not the most obvious detail to see when building an engine or the easiest concept to understand.

7T1vette

Another "subtle" item is that the distributor hold down bolt and clamp also perform the job of transferring electical ground to the dizzy. Many folks clean all that stuff up and paint it when they work in that area. But, don't put paint on the bottom side of the clamp; also, make sure the contact points of that clamp have bare metal under them on engine block and dizzy shaft hub.

{It's really annoying to fix all that stuff up and then have it NOT start.}

lars

The distributor gear is not drilled symmetrical: If you look at the drilled hole for the pin, it is aligned with a tooth "ridge" on one side, and a tooth "valley" on the other side. Putting the gear on one way or the other will change the distributor's installed clocking by one tooth. This is enough that on some Vettes, with the raised manifold rear runner and with distrubutor shielding, that the timing cannot be correctly set, because the vacuum advance can will hit the manifold runner before you get the timing right. That's why the dimple is there: to set the gear aligned with the rotor tab so the distributor will be correctly "clocked" in the block when the timing is set.

If there is no interference, the timing can be set just fine with the gear on backwards. The distributor clocking just won't be visually "correct", so people like me will look at your engine and say, "Hey - your gear's on backwards and your distributor isn't clocked right." And then you say, "Yeah, I'm just too lazy to put the distributor in the engine the right way."

Sayfoo

OK, makes sense.
Thanks

Peterbuilt

Attention to details is the sign of a superior mind.