i have a 73 chevy c10 and the timing wont stay set?

Question

i set the timing on my truck i have a chevy 350 the timing is supposed to be set at 12 deg btdc with the vaccum line disconnected i set it at that mark it runs good for a few miles then it starts running bad like one of the cylinders is missing.when i re-checked the timing it had moved to 8 deg. btdc it seems like the timing keeps moving do you think i need a new timing chain set .i have a pete jackson gear drive set but i have heard so many bad things about it i dont know if i should install it .any help would be greatly appreciated

Answer 1

Had a Ford do that, checked till blue in the face, too. If all else fails, pull distributer, and check it real close,reluctor gear may be slipping, not common, but can happen. also drive gear on dist.shaft may be loose. first though, check timing with timing light, look for the timing mark to move around while running, this will ,if it is moving, indicate that engine is not staying in time and either the timing set is bad, or probably something is wrong with distributer. I would check the distributer first as it is the easiest to examine and repair.

Answer 2

When checking timing with light, if the mark moves back and forth the timing chain/gear set is worn. After you set the timing, scribe a line from the base of the distr. to any relative hard place on the block/hold down bolt. It is really common that the distr. does not seat all the way when installed, hence the hold down bolt will be loose, and allow the timing to change as it seats and lifts. Rock the motor back and forth a little by hand after you stab the distributor...then tighten the bolt.

Answer 3

You say it begins running bad-I agree to check the dist hold down bolt first. If that is ok then you may have a sheared pin on the dist gear. If thats the case,repair is really simple if you have mechanical ability. Some pins are driven into a tapered hole so be aware.
If you'd said that the engine performance had not changed but the timing mark had-that would be a slipped ring on the harmonic balancer. I hope this helps.

Answer 4

pop the cap off the distributor and put a wrench or socket on the dampner pully and move it back and forth and see if the rotor in the dist. is lagging a bit,, possible realy worn chain or worn out dist .. easy fix on that old of a motor ,,those gear drives some times need a little fitting i would just go get a new gear and chain set and be done with it

Answer 5

Disconnect the ignition coil, then take the gasoline line off of the carb; have a helper crank the engine over, you ought to get a cup of gasoline right into a field in approximately ten seconds of cranking. it would pump staggering out the line, so don't have your face contained in the way... and no smoking. If this is large, then take the collar off the carb that the gasoline line went into, there's a gasoline clear out in there this is probable plugged. be careful to no longer harm the little white ring gasket below the collar or that's going to leak gasoline.

Answer 6

As many answers as you have and some have merrit I would chech the mechanical advance in the distributor to make sure it is not sticking. While you are there put a vacuum pump on the vacuum advance and watch the breaker plate moving. It could be hanging up also.

Answer 7

make sure your distributor hold down bolt is not loose or even worse stripped out
timing gears will almost never fail no matter what brand

Answer 8

gear drives are fine........just noisy...............but I don't think that's your problem................be sure the distributor is seated in the block properly,then be sure the hold down fork is on the distributor lip & be sure to tighten it down properly...............it should not move when tight.!.......if the bolt loosens by itself use blue locktite,just insure the threads are clean!

Answer 9

get a new timing chain

Answer 10

check the timing with timing light..did you set the distributor in time also?.