I have built ALOT of AMC V8s and 6 cylinders over 48 years of auto repair service and4x4 repairs and services . Been a auto repair facility for 40 years . Just some background experience I'm putting out here . Never once , never once ... have I had ANY cam gear or dist gear failures on any build . None . We here are having problems with offshore junk and incorrect gear manufacturing including these new China timing covers . In addition I have Noted the distributors may not be machined for proper gear mesh contact . I've been helping another member here on a DURASPARK vacuum can fail . We have found the Chinese NEW DURASPARK distributors are not machined the same externally as an OEM original DURASPARK unit . Quite a surprise to find the housing machining is not the same location as the original . I will advise everyone with fails to really consider buying a good set of OE gears . Yes even if they are used but in very good condition with no wear . Why ? Because tbey do not fail under all normal circumstances with correct OILING thru the cam gear , another major problem . I will recommend J&W JEEP Mark Duncan about buying a set or any other source for AMC JEEP engines and engine cores good for parts . Obviously don't buy worn gears that never saw an oil change . Another area for checking :
The timing cover absolutely must be checked for proper gear mesh . Do a test cover install with your dist using the yellow differential gear paste to get a good pattern . Grease won't do it .
Take it apart and note the gear mesh AND depth . How deep your dist gear engages the cam gear .
Well we know there has been a crap load of incorrectly machined gears from China along with those timing covers , and MSD CROWN and on these HEI units and others have had incorrectly made gears , including hardness issues so it is frustrating even for me to see this going on and not being resolved .
These HEI s are hit or miss as has been noted here. Some gears get torn up some not .
AMC is no different than a Buick or Ford or Chevy or dodge etc in the cam gear dist design as far as type of gears and how they work . There is not lining up of these gears BTW . Distributors get replaced all the time in vintage engines with no lining up dist gears and as soon as its running that's the end of any lining up you might have dealt with . So that idea needs to be put to rest .
OILING to the gears has been another problem as posted above . Check everything twice maybe 3 times , do a gear mesh test . Crown had impropertly machined timing covers and there's a good chance those are still out there in circulation. I highly recommend that you use your original dist gear on these HEI units . I do believe they can be swapped over . There are alot of threads on all of this and over on the AMC forums . Here we are though still having the trouble so I wanted to add my professional thoughts and to dings with experience on this subject .
SansabarJ