I have a friend who works at a mechanic shop and has set the timing on my 1989 corvette 2 times now.

The problem, is that the car is idling roughly not too bad but enough to annoy the **** out of me. I talked to him and he set and checked my timing and it ran PERFECT, better than it ever had, but about 3-4 weeks later, it started idling a little bit rough again. I talked to him and he checked and set the timing again and again same results ran fine for 3-4 weeks and now it is acting up again but still not that bad.

I was wondering if anyone had any advice on what to do or what the problem could be. He recently had a family emergency and will not be home for a good 6 months so I have to access to a timing light nor do I know how to use one. I know how to set the timing mainly but I am still not 100% sure.

Also, what could it be, is it something in the distributor hold-down bolt not tightening properly or something stupid like that, or could it be something major?

I am very mechanically inclined so most things are not issues for me and I have any normal tool that you would need except a timing light obviously.

Thanks in advance for any help that can be given.

UPDATE: I finally had time to check the distributor in my 89' corvette and it turned with ease when trying to turn it, which it should not. I then tightened the distributor hold down bolt and I could still turn it, not with a lot of ease, but easy enough that it could turn itself in normal driving.

What are my and options and what should I do?

 

I would check the see if the bolt and fork are secure. Try to move the distributor without loosening the bolt. If it moves then it is not secure.

Also make sure that you unplug the EST wire when you set your timing.

 

I found a really nice guide just now on how to set the timing. What is a good priced quality timing light you would recommend buying?

Also you said to check the bolt and the fork and see if they are secure. I'm guessing the bolt would be the distributor hold down bolt, but I am not sure what you mean by the fork.

 

the fork is the "clamp" that hold the distributor and is secured by the bolt ...

 

So, check and see if the bolt is tightened and if the "fork" wiggles at all or if the distributor turns with it tightened down.

 

I've had luck using this one over the years. There's also a gasket that is supposed to be between the distributor and the manifold. If not held tight the distributor advances based on the engine rotation.

http://www.ebay.com/itm/like/190990397848

 

I replaced the gasket for it when I replaced a bunch of other gaskets. and by the " If not held tight the distributor advances based on the engine rotation. " part that you said you are meaning the bolt and the fork right?

Thank you very much

 

Yes the distributor will move by itself. How did you make out with trying to turn it?

 

I have not gotten to it yet, I am still trying to gather info also I am installing a new sound system in the car which will take a couple days also so could be a week before I can actually do anything to check and see.

But all the info I can gather from now until then is better.

Thanks for you info.

 

UPDATE: I finally had time to check the distributor in my 89' corvette and it turned with ease when trying to turn it, which it should not. I then tightened the distributor hold down bolt and I could still turn it, not with a lot of ease, but easy enough that it could turn itself in normal driving.

What are my and options and what should I do?

Thanks for the help so far on trying to figure it out.

 

Inspect the fork and see if anything is blocking it, broken, damaged, worn, etc. If it all looks okay tighten it some more. Just don't go too tight till it breaks.

 

Remember your intake manifold is aluminum,you can't put to much torque over this bolt ,you can strip the threads,ceck the FSM for torquing specs.If you strip the threads you'r screwed...

 

I think I will just replace it if it is easy.

Does anyone have some experience with replacing them? Is it simple and easy or complicated?

I can get one locally for around $10.

Also I did tighten it, but I could still turn the distributor by hand so I am figuring it is almost 25 years old and probably worn or damaged from all the years.

 

It may be difficult because there is some things in the way. If you remove the EGR solenoid from the bracket, it should be very simple.

 

Ok, I'm gonna try to get that done today or tomorrow. Hopefully it fixes it.

 

Good luck!

 

Just pull the intake, and either run a bolt up through the bottom similar to a stud. You can then tighten a nut and washer. Or you can use a helicoil to repair the damaged thread. I say to pull the intake, because you don't want the aluminum shavings in the engine.

 

Had this same issue on our '89 and it was the "fork". I just took everything off with the clamp, cleaned it, and reinstalled. I didn't go super tight but it is snug and have had zero issues since. When the motor was run up in the RPM's hard the distributor shaft would turn ever so slightly each time. Eventually the cars power was down and it ran like poop. Good luck in your fix, it sounds like a simple one.

-Daniel

 

The threads are fine, the bolt goes in and stays tight. I just checked it and with the bolt tight and the wrench holding it in place the distributor still turns.

 

Is it hard to replace the clamp with it on the engine? It looks to be just unscrew the bolt all the way and take off the clamp and put the new clamp on along with a new bolt.