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Discussion Starter · #1 ·
Hey guys I'm getting conflicting info about the depth of setting a distributor gear and was hoping someone could clear the air for me. I dug this article up in an old post. And also this is the instructions that came with the msd gear. About .030 difference. Which one is correct?

I cant get image to load but instructions from msd say 4.005 max to 3.996 min.

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HI As long as your distributor shaft is tight the gear has a locating pin and the shaft has a hole to me there is no way to set the depth other than the gear might have a longer over shaft on it where the pin goes...

Maybe when you order the gear you have to know that measurement so the hole is in the proper place

good luck take care be safe
tim
 

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Discussion Starter · #4 ·
The new gear i got is almost .100 different from what I have . My original measurement matches the msd measurement. But my gear is wore slap out. Razor thin. Not many miles neither. Something isn't right.
 

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What kind of cam are you running? Flat tappet or Roller?
Gear material?

The MSD measurement is with the end play taken out. Dropped it should be 4.028 to 4.038

As the block ages the dizzy moves slightly closer to the thrust surface.

When installing a new gear you rotate the HOLE in the gear 90* to the original hole and press the gear on until you have the proper extended / dropped measurement.

I tend toward the shorter of the dropped spec as you must avoid shoving the gear thrust surface into the block thrust surface !!!

That 4.00" measurement with the thrust taken out or shaft pushed toward distributor body is VERY IMPORTANT !!!



Scotty J. "AKA" The "Mad Porter"
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Discussion Starter · #7 ·
The msd measurement was 3.996 to 4.006

The ford measurement was 4.028 to 4.038

My original measurement was 4.007. But wore out.

I'm still confused which to go with. This is a flat tappet hydraulic cam and the gear is just cast as crower informed me to go with

Thanks for yalls help!
 

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If I remember right...... I think it was Moroso that used to sell shims for SB and BB Chevy (yeh I know) distributors to get the right height on them for proper tooth pattern on the gears. They were very thin plastic shims if I remember correctly... Since the low side of the spec is right where Scott said at 4.000 I'd set it there and see if you can find or even make some shims to put it where you need it. Side note, these would go right under the o-ring at the top of the distributor..
 

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Discussion Starter · #11 ·
so i need to set the depth at 4.028 to 4.038 with the shaft pulled down? thats close to what i measured on the block. what kind of clearance is expected between the gear and the thrust surface? ive read another post that was claiming the aluminum msd distributor would grow with the heat.

im sorry for all the questions im just trying to make sure i understand. the other gear was ate up. im trying to make sure i dont make that mistake again.

if the gear is to high will that cause premateure wear?
 

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I am going to try this again.

The MSD measurement is with the shaft compressed or pushed toward the distributor body.

The ford measurement is with the shaft pulled away.

The gears thrust surface is supposed to float on the block's thrust surface.

If you have severe gear wear with the measurements you've laid out I'd check the oil supply at the distributor shaft / gear thrust boss in the block.

Spin the 5/16" distributor drive CCW with a HD drill to see if oil is coming up through the boss.

If the front cam bearing is misaligned or improperly installed the passage can be blocked.


The difference between the compressed and hanging measurements is the thrust clearance in the dizzy shaft moderated by the collar above the gear.







Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
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ParklandAutoMachine.com
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"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
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Discussion Starter · #13 ·
Oh ok . I think I got you now. It doesn't matter which measurement you use as long as your pushing/pulling in the proper direction relative to the specs your going off of.

In that case my original gear was set right. So I need to check oil flow at the gear. I did drill a 1/32 hole in the oil plug but the dizzy gear. Like I read to do several other places

Thanks!
 

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Discussion Starter · #14 ·
Ok so I finally got some numbers of 3.997 pushed toward the dizzy and 4.038 PULLED AWAY from the dizzy. If im understanding correctly I should be good right? Its doggone tough to be accurate with my press.
 

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I just use a .003 round shim. Grease gear side so it stays with the gear. Put it in the block and tap the shaft till it seats, pull it back out and drill a new hole for the pin. One word of caution, don't reuse a roll pin, not in this instance anyways.
 

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The new gear i got is almost .100 different from what I have . My original measurement matches the msd measurement. But my gear is wore slap out. Razor thin. Not many miles neither. Something isn't right.
Oh ok . I think I got you now. It doesn't matter which measurement you use as long as your pushing/pulling in the proper direction relative to the specs your going off of.

In that case my original gear was set right. So I need to check oil flow at the gear. I did drill a 1/32 hole in the oil plug but the dizzy gear. Like I read to do several other places

Thanks!
as scot said the bearing could be the root cause.This will also lead to crazy fast chain wear.I have drilled the cam and gear.You want to avoid preload when you tighten the dist.
 

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Discussion Starter · #19 ·
I just use a .003 round shim. Grease gear side so it stays with the gear. Put it in the block and tap the shaft till it seats, pull it back out and drill a new hole for the pin. One word of caution, don't reuse a roll pin, not in this instance anyways.
Yep that sounds easy enough thanks!
as scot said the bearing could be the root cause.This will also lead to crazy fast chain wear.I have drilled the cam and gear.You want to avoid preload when you tighten the dist.
When you say bearing you are referring to the gear to block clearance right?
 

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Yep that sounds easy enough thanks!

When you say bearing you are referring to the gear to block clearance right?
He is referring to the front cam bearing which must be indexed properly to allow oil to get to the passage that supplies the dizzy shaft and gear.

If you don't have oil there severe gear wear can result.




Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine
 
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