Today we think we know more than we knew yesterday. When I picked up the engine from the builder, he handed me the Ford distributor which he had taken apart, i.e., pressed out the shaft.
There was clear evidence that the distributor shaft was being galled by the bushing inside the distributor housing!
At last we have a relatively clear suspect in the distributor gear / cam gear failure!
THEORY:
The distributor shaft binds in its bushing, causing overload on the drive gears, which fail after 812 miles.
Other evidence includes the following:
1) there is considerable scuffing or galling on the distributor shaft itself. The bushing appears to be more than an inch in height (along the direction of the shaft axis), giving it plenty of area to "grab" the shaft and try to slow it down. Kind of like a miniature Prony brake (remember the things that used to be used in dynos in the Dark Ages to load up an engine?).
2) There is a scattering of baked and blackened grease on the shaft itself and inside the distributor housing.
3) And last, but most ominous, is the dreaded stamp "REMFG" on the housing of the distributor, which marking was not noticed until after the failure. This is the very distributor that Ford supplied with this crate motor.
CORRECTIONS APPLIED:
We installed new cam, distributor drive gear, a new MSD distributor (this one has a BALL BEARING, not a bushing) and a new Melling
oil pump.
The old
oil pump didn't seem harmed but putting a new one in was felt to be a safety factor.
All of the dimensions invloved were checked and double checked. The depth of the distributor mounting surfaces (must be 4.000" in this engine) and the distributor drive gear mounting location.
By the way,
check your MSD distributor! The gear location on the one I got (new) was off by more than 0.010" which could definitely contribute to a failure.
WHAT'S AHEAD:
Where from here? Well, the engine may go back in as early as today. If the new trans is ready tomorrow (another story, sigh) it will go in tomorrow. The new torque converter from Edge Racing arrived yesterday to replace the TCI unit which may be part or all of the cause of THAT failure.
Also, I will notify Ford, send them parts as they deem fit, and request some pecuniary salve - I want some money back for this failure!
In the meantime, the distributor will be plucked out early and often to check its condition. Once burned...
I'll report back on progress on all fronts if and as anything of any significance happens.
Driving the car is too much fun to let anything like these problems stand in the way,
Tom