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Joined: Mon Jan 27, 2014 4:31 pm
Posts: 39
Radials Rule: Roller lifters Roller rockers Roller bearings.


Sat Nov 29, 2014 3:27 pm
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1744
Sand Cast 4500


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Thu Jul 27, 2017 5:57 pm
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Joined: Mon May 15, 2017 4:04 pm
Posts: 80
tuner wrote:
Radials rule.


Did the valves have to be adjusted often? Looks like the valve covers come off pretty fast. What kind/year plane?


Thu Jul 27, 2017 6:26 pm
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The engine is a Russian M14P which has a reputation for being extremely reliable. The valve lash in this one is checked at the regular maintenance intervals and as far as I know has not needed adjustment for several years. The valve covers themselves are aftermarket foo-foo, the cable retaining system is standard.

1965 Nanchang CJ-6


Thu Jul 27, 2017 7:19 pm
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Joined: Mon May 15, 2017 4:04 pm
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Thanks for the reply Tuner. I was off a few years, figured it was a Korean War (Police Action/Conflict) area Russian or Chinese deal.


Thu Jul 27, 2017 8:17 pm
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Shimming the end play down to .002" lowered the shaft so much it caused the spark to jump from the button to the rotor and make this pattern in the button. Chinese HEI clone for Chevy V8. MSD billet distributors (and copies of MSD) have the similar problem, the shaft is shimmed to so little end play it is at least .060" lower than the OE GM design with "too much" end play and the arc jumping from the carbon button burns up/eats away the button.


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Mon Jul 31, 2017 1:54 am
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Joined: Tue Feb 18, 2014 1:48 pm
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Tuner,

What spec would you recommend to shim the distributor lower gear. I believe the factory gears have approx .090 up/down play.

I always thought the rotor contact would stay in contact with the cap button.


Tue Aug 01, 2017 5:15 am
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Because of the constant upward thrust of diving the oil pump I don't think the end play matters. If end play is causing the timing to scatter there is a bigger problem with the oil pump, which is constantly hammering on the distributor. High volume / high pressure oil pumps cause a large torsional vibration in the pump drive shaft, distributor shaft and distributor advance mechanism. It is that constant oscillation that beats the weights and pins to junk. Pumps which have the pressure balance passages (grooves) around the gears significantly reduce or eliminate the oscillation, but some folks don't like them because the have low pressure idling, 15-20 PSI below 1000. I say so what, millions of engines have gone millions and millions of miles just like that and because of idiot lights with a 10 or 8 or 6 PSI threshold nobody is the wiser. If you have a large enough (3/16" ~ 1/4") line to the oil pressure gauge you will see the pressure needle move with the tach needle.

I don't shim a factory Chevy distributor any tighter than it is unless for some reason it is just nuts excessive - like a rebuilt unit that was tumbled and blasted so many times the housing is short.

The MSD units have shims between the ball bearing and the rotating pole piece and removing one of them gives enough end play to prevent the expansion of the aluminum housing from binding the advance mechanism. I think they need at least .010" ~ .020". With locked advance it probably doesn't matter, except for if it gets tight enough there could be excessive end thrust on a ball bearing that really isn't intended for end thrust.

The issue of the gap between the spring blade and the carbon button, bend the spring blade up a little bit.


Wed Aug 02, 2017 12:14 am
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