I ve got a new MSD 455 distributor.Cant get it to drop completely down .Lacks 1/4 inch. tried it on 2 different engines with the same results .Anyone had any problems with them?
Make sure that the gear is correct. That has happened before. The 455 has a 13 tooth gear, the 350, a bigger 14 tooth gear. I'm assuming you know that the bottom tab on the shaft has to drop into the oil pump drive shaft. That can be a pain sometimes.
The gear is correct.If you take the gear off, the dist. will drop right in .Put the gear back on it wont drop the final 1/4 inch.The MSD shaft is bigger in dia. than the gm one.
If it goes in without the gear on its the wrong gear ie 14tooth. Or its not engaging the pump shaft Because it going in all the way without the gear eliminates the shaft OD of the body being incorrect. And with it only being a 1/4 in fron dropping all things point to your just not getting it down on the pump shaft turn the pump shaft with aflat blade screwdriver and try again. Im sure its no coincidence that the oil pump shaft engages a little over 1/4in
What I had to do after a couple of times trying to turn the oil pump with a long-flat screw driver is to remove the pump housing. Drop in the distributor, repack the pump with petroleum jelly.
If the distributor drops in without the gear, then the tab at the bottom of the shaft fits into the oil pump drive shaft. The diameter of the shaft has nothing to do with it. The gear is the only variable.
They normally don't just drop in, Like Michael mentioned you have to re position the oil pump slot so it will line up as it drops into place.
You said it drops it without the gear on , so if something really is wrong with the unit the ONLY thing in my mind would be is the oil pump shaft is larger than the bore in the gear. To identify this as the problem measure the two , if thats where the problem lies either have the gear machined about 3/8 or so deep so it still is a slip fit the distributor shaft above the tooth obviously, or remove oil pump gear and have a little turned off the end of it on the lathe . If your certain something is up take the oil pump gear out and see if it will register in the gear. Then proceed with the above . If the stock gear will fit the MSD shaft , use it , roll pin may be larger in the MSD in which case would probably get pretty thin.if you drilled out the hole in the gear
I had a lot more trouble with the msd than I did the stock distributor. When I replaced it last year. The gear to oil pump tolerances were tighter so everything had to be aligned just right to get it to fall into place.
I have measured all the dia. on both distributors,and the only difference is that the tang that fits into the oil pump shaft is .010 thicker than the stock one.I also have a cam button on the front of the cam which eliminates most all cam movement.may be the combination of the 2 will not let the dist. gear drop into the cam gear all the way.Going to take a junk front cover and make a window in it to see what is going on.
Yes, but you said without the gear, the distributor drops right in, so the tang physically fits. It has to have something to do with the gear.
Here is the latest.A friend has a MSD distributor that is ready to use(no box) We put my gear on it,and it drops right in the motor.Put the gear back on my MSD distributor.Same deal wont drop last 1/4 inch.Measured every dia. on both dist. Cant find any difference.
Maybe measure the diameter of the distributor that goes into the timing cover at different points. Maybe there is a taper? I seem to remember someone having an MSD distributor that wouldn't go into the cover at all. Not sure if that was a cover issue or distributor issue, can't remember.
Is something not concentric? Can you clamp an indicator to the gear and then the shaft w/o the gear to check the housing ? The same diameters meaning what, .001? How about the O ring or groove (if it has one)?
Measure your dist from the base where it meets the manifold to the top of the gear, then install the gear on your buddies and see if it the same. A few years ago, i had a dist that was a bit over an 1/8th different . Had same issue. Wasn' t seating down on intake.Long shot, but wont hurt to check it. Good luck and keep us informed.
I had that issue , tried every thing, This is what i always do now, dip it the gear in oil , a finger wipe of transgel around the hole in cover, drop it in , keep my left hand on top of it, actually fingers on the outer edges, dont want to twist your palm up. Then just use a starter button and bump it a few times, if that dont suck it down flush , somethin be wrong ....... I also had a spare cover that i knocked a few holes in , i was interested in the actual back lash of the gears. When you do get it in i would run it for a few minutes and then pull it out and check the gear for wear or scouring ,
