I would agree about measuring to the flat pad area on the gear, but the pictures you attached made me question it??I always thought it was measured to the flat machined pad on the bottom of the gear. This is the surface that rides on the corresponding machined pad down inside the engine block. Its my understanding that the two surfaces ride on an oil film. The helix angle of the gear in rotation pulls the distributer shaft with the gear attached down to ride on the that surface in the block. If the gear is too low on the shaft, tightening the hold down clamp will smash the two surfaces together and cause damage to the gear and block. If the gear is too high, their is too much gap between the surfaces and the distributor itself might be damaged. The end play in the shaft, dictated by the collar pinned above the gear, is there for wiggle room/manufacturing tolerances and to allow the cam rotation to pull down on the shaft and gear during rotation, if that makes sense. At least that's how I've read it in my research. I think there's some Youtube videos on this too as well as other articles on the net.
Thank you very much for pulling that distributor back out and checking it! Its tricky to do with one person. It looks like a nice piece from your pics.
I have my original too... I had it apart to clean it and some small plastic parts ( its been awhile but I think they were on the Mechanical advance) crumbled into dust and I could not find the parts.... STill would have to install a steel, bronze or composite gear for use with the roller cam..I have an OE 85 Mustang GT dizz.
This is from an 85 GT with the correct steel gear.I have my original too... I had it apart to clean it and some small plastic parts ( its been awhile but I think they were on the Mechanical advance) crumbled into dust and I could not find the parts.... STill would have to install a steel, bronze or composite gear for use with the roller cam..
He could still return the one he is unhappy with?I would've sold you my OEM dizz,but you never responded.
You should try the Private Message system. It's why it's thereI would've sold you my OEM dizz,but you never responded.
(technically you could even bolt in down with the hold down clamp) and try pulling up on the distributor shaft. If it has a little upward travel its (the gear) probably not being pressed hard into the block surface down inside.
Sorry, I didn't realize that you were offering it for sale.I have an OE 85 Mustang GT dizz.
Thank you....gear install
It could be depending on the engine. In my case, if I did nothing, it should work out ok.
This link shows you how to measure for the exact engine you have. Using your calipers, measure from where the distributor body sits on the block down to the thrust surface pad where the bottom of the gear rides. In my case, this was about 4.040". My LMR dizzy runs from 4.035" to 4.050" in length, shaft pushed in to shaft pulled out. In theory this will work in my case because 4.040" falls in between 4.035" and 4.050". If the compressed length (shortest measurement with all the freeplay removed) was greater than 4,040" in my case, there would be damage because bolting the dizzy down would drive the gear into the thrust surface rather than letting in just rest on it.
While it technically works, it bugs me that all the measurements don't really match up with either the Ford nor MSD measuring method and the freeplay isn't great enough. In the end to make it "perfect", we can pull the gear and collar off, turn them 90 degrees, reposition them properly and drill new holes.
For the record, I've measured old Ford dizzys with 0.100" freeplay (from 4.000" to 4.100") which ran fine despite having too much freeplay. The rotation of the engine will pull the gear down properly against the thrust surface.
I am going to remeasure later today a couple more times...... The block depth measure for sure....So the gear is hovering about 0.011" above the thrust surface in the block. That's far better than the opposite scenario of being too tight. Ford says it should be 4.031" to 4.038" pulled out and your only 0.002" over that which might be negligible considering what we're both trying to measure with.
My endplay was about the same. That little washer they added above the collar is 0.020" thick BTW. I don't know why its there. I have 2 TFI dizzys from EFI cars and a points dizzy from a '69 here and none of them have that washer above the collar.
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