Non Mopar distributor advice

[Beekeeper]

Ok, so it's not about a Mopar question but I still could use a good opinion here. In addition to Challengers, I also have a 64 Vette with a small block. I recently switched over to an MSD pro billet distributor and related ignition components. As soon as I did, I noticed a high pitch whine (almost a squeal) coming from the distributor. It does it only when cold and disappears completely once warmed up. It's more annoying than anything else.

I verified that there is no binding where it connects to the oil pump shaft. I have driven it hundreds of miles now and I can see the pattern where the distributor gear meshes with the cam gear. The wear marks are perfect and it's dripping in oil so I know lack of oiling isn't an issue. After doing more research, I finally concluded that there is not enough end play in the distributor shaft but I'd love another opinion. In between the aluminum housing and the gear, there are shims and the end play is exactly .009. According to everything I've read on distributors designed like this, there should be .010 to .015 of end play for aluminum units like mine. In speaking with MSD, they verified the unit should have .010 to .015 end play clearance.

My question is: my unit is only too tight by .001 so could this reduced end play be responsible for the whine I hear when it's cold?

I can shim it differently and they make kits for this but the shims only come in .010 and .020 so adding a tiny bit of extra end play isn't very easy. If I replace the stock shim with a thinner one, my end play will increase from .009 to .022 which is slightly more than recommended.

My second question is: am I better to be a hair tight or a bit loose on the end play?

I suppose I could try it but I figured some gear head in here has more knowledge than me on this subject.

[734406pk]

Was the end play (.009") measurement obtained with the distributor installed in the engine or out?

[Beekeeper]

Out. Measured at the shim next to the gear. I found some other shims in my spare goodies so I think I can get the end play at .015. I was just wondering if anyone had experience with non Mopar distributors and could offer an opinion on whether that tight end play might account for the high pitch whine.

[734406pk]

Out. Measured at the shim next to the gear. I found some other shims in my spare goodies so I think I can get the end play at .015. I was just wondering if anyone had experience with non Mopar distributors and could offer an opinion on whether that tight end play might account for the high pitch whine.

Understood  . I would recommend checking the distributor end play while installed in the engine. It may be even less than .009". A dial indicator would be needed to measure IMO.

[cudabob496]

what does MSD say?

[734406pk]

.010"-.015" installed. Sounds about right.

[Beekeeper]

Msd did not offer an opinion on the noise, only that the clearance should be .010 to .015.

[734406pk]

On Chevrolet small blocks, the distributor gear indexes the oil pump drive shaft and turns the oil pump. If you have too little or no end play with the distributor installed, the drive shaft will be pushing down on the oil pump gear eliminating the oil pump's end play as well. If that's the case, you can get a whining type of noise, depending on how tight it is.  You should have the same .009" end play on the distributor installed in the engine. You can slightly reduce the thickness of the supplied MSD thrust washer by removing it and sanding it down with fine (220 etc)wet/dry paper glued to a flat piece of glass or steel plate. Use a micrometer and take off .001-.002" from the shim thickness. It won't take very long to do.
 Also, do you know what the oil PSI is when the engine is cold? 

[Beekeeper]

On Chevrolet small blocks, the distributor gear indexes the oil pump drive shaft and turns the oil pump. If you have too little or no end play with the distributor installed, the drive shaft will be pushing down on the oil pump gear eliminating the oil pump's end play as well. If that's the case, you can get a whining type of noise, depending on how tight it is.  You should have the same .009" end play on the distributor installed in the engine. You can slightly reduce the thickness of the supplied MSD thrust washer by removing it and sanding it down with fine (220 etc)wet/dry paper glued to a flat piece of glass or steel plate. Use a micrometer and take off .001-.002" from the shim thickness. It won't take very long to do.
 Also, do you know what the oil PSI is when the engine is cold?

I have always used a nice thick gasket on top of the intake which lifts the entire distributor up about .020 after compression. What I did was remove the gasket to check if the unit was too close to the oil pump shaft. I found that it dropped all the way down to the manifold and rested on the bare metal. While holding it down, I could still jiggle the shaft a little bit which told me it wasn't binding on the oil pump shaft. With the gasket back in place, even after it's fully compresssed, it's definitely has .020 or so clearance at the oil pump. Maybe more since I have no way to check how much further it could have dropped had it not bottomed out on the intake. A good thought on your part. The oil pressure is around 75 cold and 50-60 hot depending on rpm.

I agree with you on sanding down the washer. My plan this morning was to do exactly that. MSD uses a thick brass washer against the housing and a .032 steel shim against the gear. I have extra distributor shims. I can replace the .032 steel shim with a .020 and .010 steel shim (stacked). Then sand the brass washer ever so lightly until I get exactly .015 clearance. I'll know by lunchtime if this fixes the issue. If not, I suppose it could be something about the tolerance of the distributor shaft as it passes through the housing and internal ball bearings.

[Aussie Challenger]

Another possibility is that the shaft in the distributor is not getting enough oil, is there a hole in the housing to lube the shaft?
Once the engine heats up and the oil has splashed around the noise disappears!!   

[Beekeeper]

Actually there is a hole for oiling. 

So I got the clearance to .015 and no noise when I started it up. I'm hoping this is it!

[734406pk]

  I hope that solves it! Wow, that was a weird issue BTW!

[cudabob496]

Actually there is a hole for oiling. 

So I got the clearance to .015 and no noise when I started it up. I'm hoping this is it!

are you using regular or synthetic oil?

[Beekeeper]

are you using regular or synthetic oil?

I use Kendall GT1. An engine builder friend who also races really swears by the stuff. Pretty sure it's not synthetic.

[cudabob496]

I use Kendall GT1. An engine builder friend who also races really swears by the stuff. Pretty sure it's not synthetic.

some significant advantages to synthetic, but the subject has
been discussed forever.