Timing Question?

[Chuck M.]

I know that this has been discussed ad nauseum but I dont know where else to go. I am going to sound like a rookie but we are having timing issues with our 67 L-79...I think. We recently had our carb rebuilt (Jerry Mac.) so this is the only new variable we can think of. The car ran well before we had to have the carb rebuilt. Since we received the carb back it no longer wants to run when under load (about 2500 rpm). It will star just fine, high and low idle fine too. We checked the timing today and noticed that it was right around 12-14 BTDC. I believe the factory setting is 10 degrees BTDC. When we tried to set it at 10 degrees it would hardly idle.

I am sure I will need to provide some more info but any guidance would be appreciated.

Thanks,
Chuck

[Timothy B.]

Re: Timing Question?

Charles,

When was the last time the points were looked at for pitting and the dwell checked?? Start there then set the correct timing.. I can't recall if the L-79 idles near the point when the centfrifugal advance starts so be careful here. Make sure the vacuum advance is working properly.

When you installed the carburetor, did you adjust the curb idle emulsion screws with a fully warmed engine?

[Chuck M.]

Re: Timing Question?

Thanks for the help. The points looked good. I cant tell you the last time the dwell was checked. I dont know if we even have the proper tools to check that.

The vacuum advance is working but I dont know if it is working properly. When the vac line was removed and plugged when we were trying to set the timing there was a difference when it was re attached to the advance.

Am I right in thinking this sounds like a timing issue?

Chuck

[Timothy B.]

Re: Timing Question?

Charles,

If you set the dwell and timing you will be confident that it's correct and you can move on from there. Does not cost anything to start here..

Why was the carburetor removed for rebuild, how was the engine acting? Your problem could also be bad/sooty spark plugs or coil.

Sounds like the vacuum advance is working.

[Joe C.]

Re: Timing Question?

I know that this has been discussed ad nauseum but I dont know where else to go. I am going to sound like a rookie but we are having timing issues with our 67 L-79...I think. We recently had our carb rebuilt (Jerry Mac.) so this is the only new variable we can think of. The car ran well before we had to have the carb rebuilt. Since we received the carb back it no longer wants to run when under load (about 2500 rpm). It will star just fine, high and low idle fine too. We checked the timing today and noticed that it was right around 12-14 BTDC. I believe the factory setting is 10 degrees BTDC. When we tried to set it at 10 degrees it would hardly idle.

I am sure I will need to provide some more info but any guidance would be appreciated.

Thanks,
Chuck

Questions:

1. If the car ran OK before you had the carb rebuilt, then why did you have the carb rebuilt?

2. If the car ran OK before the carb was rebuilt, but not OK after the carb was rebuilt, then why are you looking at timing, points, air quality, full moon, tides, astrology, tarot cards.....?

You answered your own question in your first post, then you were encouraged to change the subject.

[Chuck M.]

Re: Timing Question?

yeah, after I read my post I figured someone would point that out. The carb started to leak badly and it turned out that one of the bowls was warped. I guess I should have said it ran well until it started to leak fuel everywhere.

What are the signs of a bad pcv valve? I noticed that there is an audible rattle from there (you can feel it in the hose) that I never noticed before. Could this be causing problems?

[Chuck M.]

Re: Timing Question?

after thinking about it the pcv should be rattling shouldnt it. There is a ball in there and i would assume that if its not gunked up and stuck it should be free to move. Correct?

[Joe C.]

Re: Timing Question?

yeah, after I read my post I figured someone would point that out. The carb started to leak badly and it turned out that one of the bowls was warped. I guess I should have said it ran well until it started to leak fuel everywhere.

What are the signs of a bad pcv valve? I noticed that there is an audible rattle from there (you can feel it in the hose) that I never noticed before. Could this be causing problems?

You didn't answer the second question, which, as it applies to this thread, is more important than the first.

[Chuck M.]

Re: Timing Question?

yeah right. Thats the only variable that has changed. it was supposedly tested and set before it came back but that really doesnt mean anything. We will work on the carb.

[John H.]

Re: Timing Question?

Chuck -

If you don't have them, you need a dwell meter, vacuum gauge, and a dial-back timing light; those are absolutely essential tune-up and diagnostic tools for these old cars. Without them, you're just guessing.

[Dennis O.]

Re: Timing Question?

I had the exact same problem with my '68 convertible about 10 years ago after I had the engine rebuilt. After hours and hours of fooling around with it, I found out that the damper on the front pulley had slipped and the timing marks were no longer in the right position. Fast forward to last year; I just got the engine for my '67 coupe rebuilt, and couldn't get it timed right. It ended up being two things. First, although they had completely rebuilt the engine, they just cleaned up the old balancer and put it back on without rebuilding it; guess what, the balancer had slipped and the timing marks were off again. From my experience, it seems that after 30 or 40 years, the elastomer in the balance gives up and the balancer slips, probably when it is reinstalled. The second thing? When they re-bushed the distributor, they installed the drive gear on the distributor 180 degrees off. In a mid-year at least, the manifold and the coil make getting the distributor to advance enough without moving a couple of teeth is impossible.

Just some things for you to consider. How did I confirm this? I set the timing with a vacuum gauge (turn the distributor until you get the highest vacuum and then retard it a bit). If everything else is OK, it should run, start, and idle great. Then put a timing light on it; on both of my cars, I couldn't even see the timing marks unless I looked waaay up on top. When this happened the first time, I couldn't accept that the timing marks were wrong; trust me, they were.