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Discussion Starter #1
I just ordered a GM style HEI distributor, for either my 429 Bronco, or my 400 F250. They are both flat tappet cam engines. My question is, what material should the drive gear on the distributor consist of? The distributor comes with a hardened steel gear.
 

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You are going to want a iron gear, but you may have a steel flat tappet cam?. I know the stock flat tappets took iron gears. Also which dizzy did you get? I'm in the market for one as well
 

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I just ordered a GM style HEI distributor, for either my 429 Bronco, or my 400 F250. They are both flat tappet cam engines. My question is, what material should the drive gear on the distributor consist of? The distributor comes with a hardened steel gear.
First off let's get the terminology straight so we are all on the same page.
The cam drives the distributor; therefore the distributor is the driven gear, and the cam has the drive gear. If the distributor "driven" gear is harder than the cam "drive gear" then it is possible you can wipe out the cam gear. This happens a lot when someone purchases a clone distributor that is made in a country that does not either care or have the ability to control the hardness of the metal supply during the manufacturing process. It is a bit of a you get what you pay for when it comes to quality control. A $55 distributor is just that!

Destroying a cam drive gear can be costly, so whenever I build an engine, I purchase a matched set of gears, or I remove the driven gear from the used distributor, and swap it into the new distributor. This is of course if it is serviceable. If you put a clone distributor in a used engine, you will get some wear just because the two gears have never meshed before. If the new driven gear is harder than the drive gear, guess what happens...

Not sure this is an answer to you question, but wanted to get the basics covered so you can decide for yourself if it is worth the risk. If you have the old distributor, I'd remove the gear and run that one. My two cents.
 

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Discussion Starter #4
Thx for the reply BioTex. Yes, I do still have the OE 49K mile points distributor, so hopefully I can use its gear. Right now, I am running a 400 DS II distributor. I sent a message to the seller, questioning the gear. Be interesting to see their response.

Once I get the new unit, I will install and report back.
 

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Thx for the reply BioTex. Yes, I do still have the OE 49K mile points distributor, so hopefully I can use its gear. Right now, I am running a 400 DS II distributor. I sent a message to the seller, questioning the gear. Be interesting to see their response.

Once I get the new unit, I will install and report back.
That would be a good move IMO. Make sure the fit is proper of course. Add shims if needed. One way to give you a rough idea is to try to drill through the new gear. If you can't scratch it, then it is most likely too hard to use. Without access to a Rockwell hardness tester, this is about the best you can do.
 
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