Well....say my engine starts to ping at 2000RPM. So I'm getting too much advance under part throttle (I'm not talking WOT).

Does this mean that my engine is only being affected by the over advance around 2000RPM...or will my lower RPMs be also be affected. Basically, too much advance will result in pinging, which would kill power and fuel economy. You normally won't get the results of pinging (power loss and bad MPG) without the audio companion. [I asked someone if it was possible to not ping, but still be too advanced and losing power and MPG, I was told no]

So if I'm not pinging under 2000RPM under part throttle...does that means it's 100% ok there?

 

No,,,, just because you're not hearing any pinging doesn't mean its just right. Could be an expensive assumption.
advancing the timing "till it knocks" and then backing it off a bit will not find the most efficient timing point.

 

If you can hear the pinging your usually doing some serious damage. A knock sensor picks up pinging that you cant even come close to hearing. You best bet is to start off retarded and keep advanceing. When your performance or milage starts getting worse go back to the last setting you used.

 

The usual culprits (assuming at WOT you get no knock):

1. Centrifugal advance is kicking in too fast (at too low an RPM).

2. Too much vacuum advance or it just doesn't like being hooked up to a full-manifild vacuum source- try a port on the carb that only supplies vacuum ABOVE idle/very light throttle.

Or a combination of the 2. Try disconnecting your vacuum advance temporarily and see if the problem goes away just as a diagnostic aid.

 

WOT has no pinging, and the car has power again.

I tried running on the ported, 1 attempt at WOT it pinged bad and pinging at 1400RPM at part throttle and I knew it wasn't going to work. Just too much advance, both vacuum and mechanical. THe problem with ported for me is, my engine doesn't want to idle well unless it's getting like 14* initial timing. With full manifold I can run like 8* intial, and the vacuum advance pulls my timing up so I get a nice smooth idle. With ported, I have to run 14* intial, then when mech or vacuum comes in, I would pinging under part throttle and WOT. I'm still waiting for accel to e-mail me back about the so called "adjustable" vacuum advance. My manual says my vacuum advance on the distrib gives 10* @ 10" WC, and I can turn it up and down. But I have no idea what it does. If it limits how fast it comes in, if it limits total....or whatever.

With full manifold, I have my intial set REALLY low, and I'm using vacuum advance to bring my intial timing up.

Ede/dank, that is def what I needed to hear. I've been driving around the past few days on full manifold setup. The car wasn't pinging when just cruising around town (below1500RPM) but if I wanted to accelerate quickly and I get it a little more gas it would go to like 2200RPM and start pinging slightly. But it wouldn't ping if I just accelerated very slowly.

I backed my intial timing off again. I floored it for the first time in a couple weeks and I was glad to not only hear no pinging but feel that car pull. The car doesn't "seem" to be pinging anymore even at part throttle around 2200RPM since I've backed the timing down more.

The reason I asked the question was, since the car wasn't pinging around 1500RPM before I backed the timing down, but I was still getting like 8MPG. So I'm assuming that I need to keep backing my timing down until I started getting better gas milage reguardless if it is pinging or not.

 

I want to now if this sounds like a good way to do part throttle advance. In my van what would happen if I found a level road, set the cruise for say 60 mph. Had the doghouse off, the distributer clamp just loose enough to turn the distributer, and a vacuum gauge hooked up. I could have a passenger set the timing for the highest vacuum which theoretically would provide the highest efficiency, part throttle power, and mileage. Correct? I don't know of how you could do it with a 3rd gen though. I am thinking you could put it on an emissions or other dyno that works @ part throttle. Then you could adjust your timing and fuel mix for good mileage and part throttle power.

 

10* @ 10" sounds like they may be talking about 10 DISTRIBUTOR degrees (i.e. 20* at the crank). Easy to test- set the engine at a low idle, set the timing back to something low- like maybe 4-5* (whatever you can still hold an idle at) hook up the vacuum advance canister to your hand vacuum pump and just pump it until you've got more than 10" vacuum. That will bring the vacuum advance all the way in. Check your timing again. It should now read 14-15* assuming you have 10* of CRANKSHAFT vacuum advance. If it's 10* advance at the DISTRIBUTOR then your timing will now read off the top of the stock timing tab by a few degrees.

Just make sure your centrifugal advance isn't starting to kick in when you do this or it'll scew the timing readings.

Crane sells an adjustable vacuum advance canister kit for GM large cap HEI distributors for about $13, available at all the usual places. You can use the lockout plate supplied with it to limit the vacuum advance down to as low as ~12* at the CRANK. Which should be a good starting point in a street performance application.

 

One of the better tools I've found for custom timing adjustments is an MSD adjustable timing control, it needs to be used with their box.
With it you can adjust your timing +or- 7* as you're driving. That greatly simplifies the process.
Just a suggestion, if you have a few xtra $$ and want to make the job easier.