Re: Here we go again!
I believe the note (IN BOLD FACE TYPE) in the '63 shop manual was meant to refer only to FI distibutors, but it does not say this. Anecdotal evidence does suggest that the FI distributors where shimmed up to that spec when they were built.
On lower revving engines the sloppy end play is okay and might not cause any bad effects, but on high revving SHP engines the end play can lead to point bounce and premature ignition breakup. As Clem says, I believe that snug end play will also improve the life of the tach drive cross gear. There's just no need to have the distributor shaft jumping up and down, and I can't imagine that it serves any useful purpose and suspect it may be detrimental.
I had never heard of ANY distributor or cross gear problems that resulted from shimming up the end play, and based on my own experience, shimming up the end play to the two to seven thou spec will result is better distributor operation and no ill affects.
No doubt in production it took extra time to measure and shim the end play to the tight spec on FI distributors, but they apparently just let the others slide. I can tell you from my own experience that the as built single point distributor rarely allowed my SHP engine to rev cleanly over 5000, and that's why I bought a TI in '68, but after it took a dive on me twice I reinstalled the single point in '75. At that time I had learned the secrets of how to make the single point function properly, and part of this was to shim up the end play IAW the '63 shop manual note.
Duke
I believe the note (IN BOLD FACE TYPE) in the '63 shop manual was meant to refer only to FI distibutors, but it does not say this. Anecdotal evidence does suggest that the FI distributors where shimmed up to that spec when they were built.
On lower revving engines the sloppy end play is okay and might not cause any bad effects, but on high revving SHP engines the end play can lead to point bounce and premature ignition breakup. As Clem says, I believe that snug end play will also improve the life of the tach drive cross gear. There's just no need to have the distributor shaft jumping up and down, and I can't imagine that it serves any useful purpose and suspect it may be detrimental.
I had never heard of ANY distributor or cross gear problems that resulted from shimming up the end play, and based on my own experience, shimming up the end play to the two to seven thou spec will result is better distributor operation and no ill affects.
No doubt in production it took extra time to measure and shim the end play to the tight spec on FI distributors, but they apparently just let the others slide. I can tell you from my own experience that the as built single point distributor rarely allowed my SHP engine to rev cleanly over 5000, and that's why I bought a TI in '68, but after it took a dive on me twice I reinstalled the single point in '75. At that time I had learned the secrets of how to make the single point function properly, and part of this was to shim up the end play IAW the '63 shop manual note.
Duke
Comment