Looked through some of the boxes in he back seat at lunch. Found a new valve cover gasket set and oil pan gasket set along with a new water pump gasket and front main seal from a timing cover set. Drooled on the nice, shiny Mallory dizzy too.
Then I found where he kept the munched dizzy/cam gears. Yeehaa! Is this the typical result of the oiling issue everyone talks about? The one cam gear is basically GONE on the one side.
View attachment 30845
Eek! I've had nightmares about this image. I couldn't stand keeping the broken ones around because they always made me cringe.
Answer: Yes, this
is definitely the problem that everyone (me included) has. There are a number of potential issues to check.
Everyone who experiences the problem agrees with the following:
1. Verify that the timing chain gear itself has the flashing cut out of the slot so that oil can flow from the front cam/bearing/journal. AMC always made sure this flashing was gone, but many of the aftermarket manufacturers didn't realize how critical the oiling slot is, and/or just don't bother to remove the flashing. I've had mixed results; some sets had the flashing removed, and some didn't.
2. Use a quality set of hardened gears. I've run through both Crown and Mallory. The gears need to be a matched set, that get broken-in together, with a quality break-in lube. The current iteration of my 401 is running happily with Mallory gears.
My experiences have brought me to these additional conclusions:
3. I am running an aftermarket timing chain set that came with a thrust plate that I had to drill and tap to install into the block. I therefore completely eliminated cam-walk as an issue, but the engine STILL ate a set of gears. Therefore, I am
not convinced that cam-walk is the primary cause of the problem.
4. My very first build on the 401 used a Crown timing chain cover, and I went with a bronze distributor gear to be sacrificial. This worked just fine to get me several thousand miles across the continent, and it served as a daily-driver for a summer, several wheeling trips, and a move to a differnet part of Alaska. Then I lost a lifter, which lead to a new cam, and the beginning of my cam-gear problems. I bought one or two more Crown covers, only to have the same problem. Allegedly, Crown initially mis-machined the placement of the distributor hole in a batch of their covers. The AMC-speciality company that sold me my last Crown cover mic'd the cover to verify that the hole was to spec. It still ate a gear.
5. Based on the above, my most recent engine builder asked to return to an OEM cover. We put in new oil pump gears and added Bulltear's stainless oil pump midplate. The engine has over 2,000 miles without any issues, and builds reasonable hot-idle oil pressure.