I know that a few folks here have used or are using Mallory distributors and I would like some feed back.
I realize that this instance that I am going to describe might be Healey specific, but if anyone has had a similar experience with using one of these distributors in an MG I would be happy to hear of it and of what ever repairs were needed to eliminate the problem.
I have a customer with a big Healey who first brought the car to me because no one had been able to get the thing to run properly after the new Mallory dual point unit had been installed. I proceeded to set the distributor up on my machine and make a few small mods to it before sticking it back on the engine and having the car run like a rocket ship. It has been doing just fine for many months up until a few weeks ago when oil started appearing on the right frame rail of the car. The source ended up being the weep hole in the bottom of the distributor case.
I have pulled the distributor several times now, checking things and doing little mods, but unless the next test drive ends up showing no oil leaks I am getting to a hard place.
The drain bore leading back to the sump from the distributor drive spindle cavity is clear. I first took about ten thou off of the top of the drive gear that had been swapped over from the OEM Lucas unit in order to allow clearance for the installation of a thin neoprene O-ring as a seal for the shaft where it enters the distributor body. That might have slowed things a bit, but it didn't completely eliminate the problem. Most recently I pulled the banjo bolt that joins the feed line to the tach drive house and reduced the orifice through which the oil has to flow into the cavity below the distributor. The OEM opening was about 3/16" in diameter and I filled that with lead before re-drilling a ten thou passage. I haven't put more than ten or fifteen miles on the car since then as the weather has been very rainy, but that "may" have helped a little more.
I have discussed this with Jeff and he explained that as a cost cutting effort Mallory sometime ago replaced the original true bearing and seal arrangement in their products to a simple bronze bushing.
I feel like this is a delivery "volume" situation rather than something caused by excessively high pressure, but I don't know that for sure. The oil pressure is about normal for a big Healey and the inside of the engine is extremely clean.
If anyone can shed light on this I would appreciate it.
Jack