sudden timing advance

[sazanata]

Hello all,

This weird thing happened today. I went to a gas station, and when I left, my 1969 dodge dart 318 had a hard start, like timing was too advanced, or the batery was dying. I drove home, and when going uphill, car pinged like crazy. I thought of bad gas, but decided to check the timing. Instead of the 11 degrees btdc that I have been using for 20 years, there was almost 30!!!!!

Car has a mopar eletronic distributor, and a msd 6al box.

I removed the distributor, checked everthing in it, and it looks fine. I know a sloppy timing chain retards the timing, but if this is not a problem with the timing chain, what could it be?

If I remove the valve covers, and put piston 1 in tdc, if the timing chain jumped a tooth, do you guys think I will be able to notice something wrong with valve timing?

My car has 20'' of hg of vaccum at idle, and after timing increased, it mantained the 20'' of hg. This made me think that it cannot be a timing chain problem, otherwise the bad valve timing would kill the high vaccum, no??

Any help will be highly appreciated!

Salvador

 

[RustyRatRod]

Did you try to turn the distributor before you yanked it to see if it was loose?

 

[Bewy]

Dist weights sticking? Using vac adv? Make sure the plate moves freely.

 

[RedFish]

I've never checked timing after a slack timing chain jumped a tooth or 2 but that is when it usually happen. Fine at switch off and crap at restart. I don't recall checking vacuum either. Poor run and lack of power said it all. Good luck

 

[halifaxhops]

almost sounds like a broken advance spring. Easy check take the cap off and see if the rotor advances by hand and then springs back. Check the timing and see what happend to it!

 

[67Dart273]

Loose distributor OR MOST LIKELY something bad in the dist. Something broke, something fell down in, like a screw, or rusty and stuck.

A timing chain is not going to advance the timing, it will retard the timing.

 

[sazanata]

Thanks for all replies!

The distributor seems fine, and it was not loose.

The springs seem to be returning as they should.

I did a compression test and saw 160-170 psi on all cylinders. This excludes a bad timing chain, or not?

How much slop (in degrees) is acceptable for the timing chain? It would be great if there existed some little window to inspect it, like timing belts have...

As the heads in my engine were really shoved and the pistons are cheap, with no valve relief, I am afraid my little 318 might have some interference now. That is why I am really afraid of breaking a chain...

Thanks again!

 

[67Dart273]

If you think it's the chain, is it possible you are reading the timing marks wrong? A slipped chain is not going to advance the timing.

 

[sazanata]

Dear 67Dart273,

you are right. The devil on my left shoulder is not very logic! I removed a valve cover and rotated the engine by hand: valves are opening exactly when they should. I will just adjust the timing and use the car! Thanks.

 

[67Dart273]

Well that is not to say there wasn't a problem. Maybe there was a piece "of something" debri, etc that got caught in the advance mechanism and jammed it. MIGHT be a great idea to yank the distributor and do an inspection, and it might just need some lube. The shaft is supposed to be lubed where the "top hat" advance mechanism fits, and the weights and so on are not protected from rust.