Mechanical advance distributors question

[82 GT]

My '82 has a Mallory mechanical advance distributor. Do I have to buy an advance/retard kit to adjust the timing?
I run 93 octance gas and under full throttle I get detonation.
The distributor is factory set at 24 degrees. I think I need to retard the timing a couple degrees.
Is there another way to do this?

[HotRoddin]

The base timing is set by loosening the the distributor hold down bolt and turning the distributor body... the mechanical advance is a set of counter weights that as the distributor spins faster, give you more advance.
So you can change the base timing easily.
I hope thats the question you were asking ?

[nitrousdave]

If your base timing is where you want it, you might be able to easily adjust the mechanical advance. On my old mallory unilite distributor all I had to do was take off the cap and rotor and then turn ther motor untill a small tab with some marks by it appeared. Then I just bent the tab to advance or retard the mechanical advance. I don't remember which way was which but I do remember that each mark was 2 degrees. Hope this helps.

[82 GT]

My problem is that I can't turn the body of the distributor. I loosened th hold down bolt and the body won't turn. That's why I figured I needed to buy timing keys or something.
Sooooo.....you're telling me that I am supposed to be able to turn the body of the distributor?
Why won't it turn? I thought only vacuum advance distributors could be adjusted like that.
Something's messed up then I guess.

[HotRoddin]

<<<<you're telling me that I am supposed to be able to turn the body of the distributor?>>>>

I've never seen one that doesn't turn ? I know they get stuck in there pretty tight sometimes ?

[PKRWUD]

Originally posted by 82 GT

Sooooo.....you're telling me that I am supposed to be able to turn the body of the distributor?
Why won't it turn? I thought only vacuum advance distributors could be adjusted like that.
Something's messed up then I guess.

Yes, you should be able to turn the distributor body.

Take care,
~Chris

[82 GT]

Pkrwud , how come it won't turn then? Should I put some muscle behind it or isn't that a good idea?
I'm going out there soon and see if I can get it to turn.
I'll let you know what happens.

[PKRWUD]

Soak the base where it meets the block with WD-40, and let it sit for a while. It will come loose.

Take care,
~Chris

[82 GT]

Ok, I got it to turn. It was just a little tight.
Do you think 24 degrees at the distributor is enough for the set up I have. How can I tell if I need more or less advance at the distributor?

[PKRWUD]

You do not have vacuum advance, just mechanical advance? Hmmm. Interesting. I would set it at 16 degrees BTDC at idle, and get on it hard. If it doesn't ping, advance it another 2 degrees. Keep going until it either pings, or you can feel the power drop off.

Take care,
~Chris

[82 GT]

Is there something wrong with having mechanical advance? Just curious.
Tonight I retarded the timing "about" 2 degrees(timing light is broken and I need a new one). It was pinging before and still does. I'll try a few more tommorow.
Actually, I was talking about the weights in the distributor for the advance. They just determine how fast the advance comes in...correct? My Mallory manual says it's factory set at 24 degrees.
So with it at 16 BTDC and 24 in the dist. I have a total of 40 degrees BTDC...right?
I don't know much about "fine" tuning the timing but I
DO realize that I need to buy another timing light for acurate results.

[PKRWUD]

You are exactly right on everything, and no, there's nothing wrong with mechanical advance. I'm just used to mechanical advance being complimented with vacuum advance as well. You need to get a timing light rather than guessing. You could use a vacuum gauge if you have one, though.

Take care,
~Chris

[82 GT]

Ok, I think I see how this works now. So if I had more centrifical advance in the distributor then I wouldn't be able to get away with 16 degrees initial advance. In other words, if my dist. had 30 deg. centrifical advance then I could only have about 10 deg. initial advance.(roughly) in order to stay within the 38-40 deg. total advance picture.
I know some engines can take more than 40 degrees.
I'm assuming that the more centrifical advance you have, then the less initial advance you have to "play" with.
Does that about sum up the timing thing?


Yeah, I remember once you wrote a very informative thread about how to tune a car up with just a vacuum gauge. I'll have to see if I can look that up in the archives.

Thanks PKRWUD

P.S. I also think that you should change the title under your name
to "very knowledgeable member" or "engine guru" or something like that.
That "junior member" certainly does not fit you.

Thanks again!!

[Chevyguy]

Ahh you figured it out Your problem is the total advance is probably still too high. IIRC my stang was about 32-34???? Get a dial back timing light, that will allow you to measure the full advance curve by turning the knob to bring the mark back to zero, can read to 60+ degrees that way.

Changing the weights and springs will alter the rate the centrifigual advance comes on, not the total mech advance.

Like the other guys said, most aftemarket dist will have provisions to adjust the total mech advance. 10 deg initial timing is a good place to start with 20 deg advance. Go up from there till it pings, then go back 1 deg

[82 GT]

I was messing around with my timing some more tonight but before I could go to my favorite stretch of road, I noticed white clouds of white smoke coming from both tailpipes. Now it never did that before. I ruled out head gaskets because I doubt they both just went bad. It kind of had a gas smell to it.
Could it be the rings are shot or did it have something to do with me messing with the timing. Like I said, it just started doing this tonight. It pours out pretty good.
I know the engine probably has some miles on it but...damn..I'm going to be pissed if it needs rebuilt now.
It just seems odd that I was messing with the timing and now it smokes.