[Guest]

I set the timing dead on a 9 degrees BTDC...go for a of-road run...after a few minutes the timing has slipped...the distributor has not moved...but the timing is off...so i reset the timeing...have to the distibutor about 8 degrees counterclockwise...run again...it shifts again...this time i have to move the distributor clockwise 8 degrees

so what's causing the problem?

the thing runs rough from 700 to 4000 rmp. Rigth now if i put the timeing light on her timing will be bouncing around form about 4 degrees BTDC to 12 or more?

What is the cause guys?

 

[Guest]

Souns like you have a streched timing chain. It could also be worn timing gears, but i bet the chain. Take the cap off of the dist. Rotate the engine by hand and see if there is play in the chain, by watching the rotor. I had an old 304 that the chain jumped a couple of teeth on the gear, ran like sh!t.

 

[Guest]

Thanks for the test proceedure...i'll give it a try right now and get back to you...thanks

 

[Guest]

well i tried cranking the engine by hand and holding the distributor...doesn't seem to be any slack in the timing chain...the distributor moves in direct responce to the turning if the engine....so now what? is there anything else that can cause the timing to shift randomly?

 

[140]

You can't do it that way you got to do it by hand put a breaker bar on the crank turn it one way till the rotor turns then turn it the other way and see how much you turn the crank before the rotor turns i think 7 deg is max. before you got to replace the chain or gears

Michael 78 CJ-5 304eng T150 Trans D20 transfer

 

[Guest]

Oh..i think i understand now...i'll give it a try and get back here within the hour...thanks

 

[Guest]

You might want to check a couple things in the distributor.
Make sure the centrifugal advance is working. If the upper shaft hasn't been given a drop of oil periodically then the upper shaft will stick to the lower shaft and the centrifugal advance will stick.
Also check the vacume advance parts. The pickup plate should move freely. There usually is 3 little nylon buttons that the plate rides on and when they wear out the plate rubs directly on metal.

 

[Guest]

thanks for the additional things to check out...i'm still working on this problem!

 

[Guest]

had a similar problem with my 304...pulled the timing chain cover to find out that the the chain was a little loose and had skipped a few sprockets so decided it was time to replace timing chain and now runs smoother than ever.

'77 cj7, 304, 31"tires

 

[Guest]

thanks for the input guys...it goes into the mechanic tomorrow...i would do it my self...but too busy working...so i guess i'll have to spend some of the bucks getting the thing fixed!!!

 

[Guest]

You could pull the distributor and look at the drive gear. The motor might have a few miles on it