Bronze distributor gear install ?
 

I'm trying to put a bronze gear on my thunderbolt distributor. My question is the only way it seems it is going to fit is if I take the shim or thrust washer ( not sure what you call it) out between the gear and bottom of the distributor. When I put the gear on with the shim/washer in place the distributor will not even spin, it's tight as hell. Can I run without the shim/washer between the gear and distributor?

First ???? Do you need to run a bronze gear because of billet cam gear????

The washers are actually shims. They keep the distributor shaft from moving up and down. You can get shim kits with thinner shims at any speed shop.

Yes, billet cam. So is there suppose to be any movement in the distributor? With the stock gear and stock shim there is 1/32" play. When I remove the shim and install the bronze there is very little if any play. Should I still put a shim in or run without?

My memory is not what it used to be but I think there should be .010" to .015" of play.

Dave

You should not be running a bronze gear on a billet cam gear. Cam gear will eat it alive sending shavings into engine/ causing variation in timing due to slop in the gear mesh. The newer cams have different material properties requiring a different distributor gear material.

There is a special melonized gear that should be installed. I read this and got the GM part number from Hot Boat magazine some time ago. I beleive it was an article written by Tyler Crockett (don't hold me to the author as it was years ago). I did this once and learned my lesson. Caught it very early, installed the new GM melonized gear on the distributor. Ran fine and no wear from there on out. As for you clearance issue...??? not sure

Zack

Additionally, now it has been some time ago so please forgive the memory :drink: :drool: , the bronze dist. gears are available in different sizes. Is it possible you ordered the wrong size for your application? I don't recall if it was length of the gear or the inner diameter. I just remember there was a difference somewhere...

Zack

It is the inner diameter that are different.

Stotz is spot on. Set mine w/ a .015 play. Used shims to get the tolerances.

Now I'm confused. I thought you had to run a bronze gear with a billet cam, or the Comp Cams composite gear. I've heard of the GM melonized gear but I thought it was also a cast gear like stock. I Better do some checking....

Hope I didn't confuse you. I did try the bronze gear on my new roller cam at first rebuild. I noticed the timing seemed to be moving around and couldn't keep a perfect idle (although cam was a little larger than a 741). Pulled the distributor and saw a lot of wear on the bronze gear.

Read in an old Hot Boat that the newer billet roller cam blanks required the melanized gear for the distributor due to the hardness of the billet. Hope I relayed this correctly... anyone else feel free to jump on this if I am in error!

Zack

razor, so you had a billet cam with billet gear ( not a pressed on one) and ran the GM melonized gear? I was going to do that but was told the bronze would be better because it was the weak link. It will go before the cam. Just figured I would change it every season. Maybe I will go with the melonized if you had good results...

Yes, I am pretty sure that is what I ran after the bronze gear showed severe wear. Please, check with an engine shop to verify this. I would hate for something to happen if what I have relayed to you may not be 100% correct. Call Tyler Crockett at his shop. I was able to talk to him a couple of times, and he was a wealth of knowledge.

Just , please, double check my facts before you install and have a problem...:cool:

I always do...:D Thanks

j,
Are you sure you have the correct gear for your distributor ? It definitely should have some end play when it is installed. The distributor housing grows when it gets hot and will bind up the shaft if there is no play. Aluminum housings generally require more clearance than cast iron.

Also, a lot of distributor gears, bronze or otherwise, require you to drill a new hole to get the gear installed with the correct end play, look at the instructions that came with the gear and see what they say.

Last but not least, like others have already said, you really need to call the manufacturer of your particular camshaft and ask them which gear you should be running. In recent years there have been many changes in this area of the camshaft including pressed on gears, welded on gears etc. The only way to know for certain is to call the person that made your camshaft.

Hope this helps,
Bill Koustenis
Advanced Automotive Machine
Waldorf Md

When we ran bronze gears with the Thunderbolt IV distributors, we generally had to take a few .001" off the top side of the bronze gear to get the pin thru the gear/shaft and keep the clearance right. On one distributor the bronze gear was bolt-on and on the other distributor the gear needed tweaking in the lathe. Consider taking all to an quality engine/machine shop, you shouldn't be there 15 minutes.