distributor

i recently replaced my stock distributor on my 77 cj w/ 304. i replaced it because my vacuum advance crapped out and wouldn advance. it was running real nice for awhile now, until yesterday. it just died and wouldnt restart. after alot of head scratching, i got it to start by advancing the distributor all the way and i limped it home. i pulled my distributor, the gear and pin is intact. when you hold the distributor from the gear and try to rotate the rotor, it seems like a solid piece. when the distributor is installed, i can rotate the rotor a few degrees and you can feel the rotor coming up. any inputs or experience with this???? please dont tell me my distributor gear at the cam had slipped.

 

Rotating the rotor a few degrees when installed is normal. There's some gear lash, and any end play in the distributor shaft lets the distributor gear ride up on the cam gear, and that adds some lash.

You have the stock Prestolite ignition? That's the distributor with the plastic vacuum advance? You sure you want to fix it? The Prestolite stuff isn't very reliable. The usual failures are the control unit, the reluctor coil (in the distributor) or the plug between them.

Why do you think it's the advance? Because you can turn the ditributor and the motor runs better? AFAIK the vacuum advance on this distributor is a vacuum motor that pulls on the reluctor plate, just like a points distributor. If you apply vacuum, the reluctor plate should turn, just like a points distributor.

How handy are you with electrical gadgets and electronics? If your answer is 'not very', I'd suggest you buy a complete drop-in HEI distributor for your Jeep. This will eliminate the troublesome Prestolite control unit, and the HEI is a one-wire system - all you need is power. The other possibility is the DuraSpark (Ford/Motorcraft) system from a newer 258. You'd have to wire up more stuff though.

 

i replaced the distributor because my vacuum advance leaked and would not advance. i've been driving around w/ the new distributor for about a month now until this happened. the only way the jeep would start now is if i turn the distributor all the way advanced. i cant even get near the timing spec it calls for. and when i rotate the rotor when the distributor is mounted, it would turn almost 1/4 turn....a liitle excessive for back lash

 

I would make sure the lenth of the new dist. is the same as the old one. Also did you put a new dist. cap on with the new dist? A crack and a little moisture can cause some real odd things to happen. You might try turning the cam gear with a screwdriver when the dist is out to make sure it is not loose. Does the motor have alot of miles on it? If the timing chain gets loose they can jump time. Hopefully not though. Good luck.

 

Oh yeah, jumped time makes sense. You up for taking the timing cover off? You can check the valve timing if you have a dial indicator. Look at p. 14 here: http://www.c104.net/manual/Section_01A.pdf

 

You can check the chain by rotating the crank back and forth while watching the rotor. Ten degrees is about all you want. If it is sloppier than that a timing set is probably in order.