SBF distributor gear placement

[408stang]

I have a 351W that had a new distributor gear installed. I'm curious as to why Ford has the gear placement at 4.031-4.038




And MSD has it placed at 3.996-4.005







Is there a specific reason for the difference?

[408stang]

??????????????????????

[Gaz64]

MSD's gaskets could be .035 thinner.

Or possibly MSD has worked out how to cut a gear, and mesh it tighter for less backlash without making a whine.

Bit like setting pinion height in a diff.

Do whatever the distributor manufacturer says to do.

[408stang]

Over a week, and can't one simple explanation from MSD? Let's cut to the chase here. All I'm looking for is to why MSD would list gear placement different than ford? The gear is deigned to run in the endplay of the distributor, while riding on the block, and that's determined by the distance from where the distributor seats in the block, to the place in the block where the distributor gear rides.

I bought my 8578 distributor brand new, and took the cast gear off, and put a steel gear on because that's the gear Bullet cams recommended to run with my 1050 core cam. I placed the gear according to Fords specs, and ran it. After about 1000 miles of drive time, I decided to recurve the distributor, only to find it had a few issues. MSD took it in for some warranty work, and at the time I pulled it, the distributor gear looked fine. When it was sent back, I noticed that MSD had put another gear on as well, which was not related to the warranty issue. That was a nice thing to do, but I did notice they placed the gear 3.999, which is in their specs, and not where I had it.

I didn't want to take it to a machine shop to have it moved, and it was in their specs, so I decided to run it. After 1000 more miles, I pulled it out, only to be very discouraged by the gear. What I saw, led me to pull the cam, which was pretty aggravating.






So now that a week has passed, can someone from MSD please explain to me why their gear placement is different than Fords?

[msdtech1955]

i see you also posted this on yellow bullet too.


lets keep in mind, that the ford gear is pulled down against the block
( in the photos included)


ford's drawings shows the shaft "pulled out "...to get the gear height (,where as our distributor endplay is setup from (.025 to .035). that is from the lower housing to the collar.. then we "push the collar" against the housing
to set up the gear height ...from 4.005 to 3.996.
basically , if you measured the ford drawing to ours...we would see that they are the same......we are accomplishing the same goal .DSCN7119.JPG

DSCN7115.JPG

[msdtech1955]

on that cam....i need to see the distributor gear .... that photo shows me ...that material came off ..like wrong material of gear.....

was the gear you installed ...ruff looking or smooth ...around the collar ?

[408stang]

Originally Posted by msdtech1955

i see you also posted this on yellow bullet too.


lets keep in mind, that the ford gear is pulled down against the block
( in the photos included)


ford's drawings shows the shaft "pulled out "...to get the gear height (,where as our distributor endplay is setup from (.025 to .035). that is from the lower housing to the collar.. then we "push the collar" against the housing
to set up the gear height ...from 4.005 to 3.996.
basically , if you measured the ford drawing to ours...we would see that they are the same......we are accomplishing the same goal .Attachment 2134

Attachment 2135

Exactly the type of explanation I was looking for. Yes, I've posted it in a couple of places, because I feel like I've covered everything thoroughly, and I can't figure out why I've got this excessive wear with just a few thousand miles. I've checked endplay, I've checked gear placement, and I'm not using and HV pump. Basically, I've got no explanation as to what is going on. I sent the cam back to Bullet, and they told me that they believe that cam will be ok to run, so I'm going to try it. Kirk told me that in his opinion, there's too much endplay, the distributor shaft is bent, the distributor gear placement is off, or the distributor gear is not cut correctly. He checked the cam gear and said its perfect. But that's the way this game seems to work. It's always someone else's fault.... Endplay is .003. I'm going to go have a machine shop set the distributor up and spin it to check the shaft because I don't know what else to do??

Originally Posted by msdtech1955

on that cam....i need to see the distributor gear .... that photo shows me ...that material came off ..like wrong material of gear.....

was the gear you installed ...ruff looking or smooth ...around the collar ?

I'm out on business right now, and the dist gear and cam both just came back from Bullet. I'll get you some pics tomorrow, possibly. It's a 1050 core cam, which according to Bullet, is compatible with a steel gear, which was on it. I can tell you that the wear on the distributor gear isn't uniform. Deep on one side, and shallow on the other, along with being high on one side and low on the other.


I can guarantee you that I'll run a brass one now though. I've already got one ordered, but they're backordered. Kirk at Bullet told me to only expect a few thousand miles from one with the 1050 core cam though.

The only thing I'm looking for, is a good reason why I have this wear. According to Bullet, I can run the cam, so all I'm out is a $50 gear. I just want to know why it's like this because I've got to put it back together, and something obviously wasn't right. I need to know what that something was.

Thank you for the replies.

[408stang]

Ok, here is the gear. You can see the uneven wear pattern on it. I guess I'm lucky I caught it before it tore the cam gear up too bad. I'm still leary of using the cam, but I'm taking the word of the people who built it, over mine. Their experience far outweighs mine.

Now I'm hoping you can share your opinion as well. As I said, the good people at Bullet cams said their opinion is camshaft endplay, improper distributor gear placement, a bent distributor shaft, or a bad distributor gear. What do you guys think?

Basically, I want to know where to look when I put this thing back together. Something was not right, and I want to fix that.

[408stang]

[Gaz64]

The gear seems to have uneven irregular wear on the drive side.

One of the gears is cut incorrectly.

Does this drive a high volume oil pump?