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Which distributor gear??

Ly-mo

Jr. Member
Joined
Apr 7, 2014
Messages
54
I'm getting ready to buy a replacement distributor on RockAuto. Looks like they list Duraspark distributors with both cast iron and steel distributor gears. Anybody know how to discern what's supposed to be in my truck?

It's a 1976. I believe the engine was pulled from a 77 Monarch in roughly 1990 and built with a mild Crane cam.
 

DJs74

Bronco Guru
Joined
Apr 1, 2014
Messages
1,135
The distributor gear material needs to be matched and compatible with the camshaft type / material.

See below


Common Camshaft / Distributor Gear matches:

Hydraulic Flat Tappet Camshaft – Most cast iron or composite gears
Mechanical Flat Tappet Camshaft – Most cast iron or composite gears
Hardened Steel Hydraulic Roller Camshaft – Hardened steel or composite gears
Hardened Steel Mechanical Roller Camshafts – Hardened steel or composite gears
Billet Steel Hydraulic Roller – Bronze or composite gears
Billet Steel Mechanical Roller – Bronze or composite gears


DJs74
 
OP
OP
Ly-mo

Ly-mo

Jr. Member
Joined
Apr 7, 2014
Messages
54
Thanks DJs74! That adds up- it's a flat tappet hydraulic cam, pulling the trigger on the piece with a cast iron gear.
 

DJs74

Bronco Guru
Joined
Apr 1, 2014
Messages
1,135
Thanks DJs74! That adds up- it's a flat tappet hydraulic cam, pulling the trigger on the piece with a cast iron gear.

That should work fine.

When you install the new distributor, apply a generous amount of lubrication to the distributor gear. The distributor may come with some - if not, your local auto parts store will have a tube or small size container... you're just looking for something to protect the new gear at the initial start up.

DJs74
 

latrucker

Contributor
Sr. Member
Joined
Jul 19, 2010
Messages
614
Be careful, a performance flat tappet cam can have a steel distributor drive gear on it. Want to know how i know this. I replaced mine thinking ALL flat tappet cams took cast gears. Bronco ran for about 100 miles and died and never would start, pulled the distributor and all the teeth were chewed off. Pull your old distributor and check the current gear to see which gear it has. Its not hard to tell the difference between iron and steel. Much easier than tearing your motor apart because its full of metal shavings. Not trying to be a downer here, just don't want you to go through what i went through, it was horrible!!!
 

Bart

Contributor
Bronco Guru
Joined
Dec 12, 2001
Messages
1,678
Loc.
Buffalo Gap, Texas
Be careful, a performance flat tappet cam can have a steel distributor drive gear on it. Want to know how i know this. I replaced mine thinking ALL flat tappet cams took cast gears. Bronco ran for about 100 miles and died and never would start, pulled the distributor and all the teeth were chewed off. Pull your old distributor and check the current gear to see which gear it has. Its not hard to tell the difference between iron and steel. Much easier than tearing your motor apart because its full of metal shavings. Not trying to be a downer here, just don't want you to go through what i went through, it was horrible!!!

Okay, it's not hard to tell the difference. Just how does one tell the difference between the two? I have a fresh 90 5.0 mustang roller motor. My problem is that the distributor goes in easy no matter where I stab it. I've done a fair number of engines and it's always been "fun" getting the timing and the oil pump to match up. Not the case now. No matter where I put the rotor in the distributor goes all the way in. I did notice that there are two different sizes of hex drive shaft. I have the smaller one installed and the distributor is the same size (verified). It just bothers me that the darn thing goes in easy no matter where I put it. I plan on contacting the engine builder tomorrow with the same questions.
Anyway, how does one tell the difference in gears?
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
Be careful, a performance flat tappet cam can have a steel distributor drive gear on it. Want to know how i know this. I replaced mine thinking ALL flat tappet cams took cast gears. Bronco ran for about 100 miles and died and never would start, pulled the distributor and all the teeth were chewed off. Pull your old distributor and check the current gear to see which gear it has. Its not hard to tell the difference between iron and steel. Much easier than tearing your motor apart because its full of metal shavings. Not trying to be a downer here, just don't want you to go through what i went through, it was horrible!!!

I had a Sig Erison flat tappet cam like that. It needed a steel distributor gear.
Best to check with the cam manufacturer.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
If it is stock, cast iron is correct for a '70's engine.

If aftermarket, check the cam manufacturer. I had an isky roller cam that took a cast gear.
 
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