Am I Timing this correctly????Need Help with Pinging

[schnerdad]

I just finished up my TFI upgrade with a used MSD 6A module.....Runs fine, Strong, Fast responce.... so of course I had to mess around a little more with it and seem to have developed some annoying pinging......I Broke out the timing light and settled on about 10.5 Degrees BTDC.......I then added the Mr.Gasket 925 dizzy springs.... Took her out for a spin, she runs strong but noticed pinging between 3/4 and full trottle from a dead stop..... pinging goes away at about 1/2 throttle.... No ping at idle.............So I decided to do the vacuum timing deal.....then checked with the light....is now at around 8 degrees.....A little less pinging but still there...annoying as all heck........I do have a carbon buildup problem that I was going to give the Seafoam treatment this weekend, when I can get it out on the highway (Smoke)....and I did just fill up the other day with a full tank of 87 octane(with prices these days thats all I could afford)... I've used 87 before and never noticed any pinging at all.............So My questions are, Does the 8 degrees sound right??.......Could the new springs be causing the dizzy to advance too far? Too fast??? I don't have an advanced timing light, and if I can't afford the gas then I'm not gonna be able to buy another light either....besides I thought that the dizzy could only advance so far...ie 35degrees or so no matter if its vacuum or mechanical advanced or both......Or could it just be that they're putting out cheaper gas these days???? Any advice??????

[GWChris]

Pingging under heavy load is probably too much mechanical advance. Pingging under light throttle is usually too much vacuum advance. Both can be influenced by a lot of other issues.

Pingging under heavy load is MUCH more of a serious problem.

I'd put the dizzy springs back where they were and see what happens then.

Is your EGR connected?

[schnerdad]

Yes EGR is connected, as is all the rest of the vacuum system, It was gone over and completely replumbed with all new vac hoses, and all are in good shape....the engine is stock, except for the TFI and MSD upgrades...............So reinstall the original springs then, and give that a go? How about the 8 degree intial timing, is that ok?

[DanHS]

Connect the vacuum advance directly to manifold vacuum, set the vacuum advance to start moving at about 7 inches vacuum (using the little hex key inside the vacuum port). Then mess around with it from there, try it with and without the springs, first without.

When I installed my TFI the more powerful spark caused it to ping like that, so I ditched the cto and connected straight to manifold vacuum as per Ristow's reccomendation, then messed around with the vacuum advance setting. I still need to mess with it more but it's far better than it was.

[GWChris]

8 degrees initial advance seems light to me. I run about 12, with the big cap and Ford E-core coil. I have stock springs in the dizzy, I run straight manifold vacuum advance, and I've tweeked the vacuum advance as Dan mentioned. No pinging on 87 octane.

What bothers me is that all the effort I put in was to eliminate part throttle ping, which is mostly a big annoyance and is pretty typical of these Jeeps. If you've got detonation under heavy load, that's a ticket for major engine damage.

Unlike others, I see no point in the vacuum timing method at all. With the stock springs set the mechanical timing at idle as specified stock with a timing light, so that you know the total advance is correct. Then adjust the vacuum advance canister with an allen wrench so that it doesn't ping anymore - CCW reduces the advance at a given vacuum level. In the end you want to run as much vacuum advance as you can get away with, without having the total advance under load get out of hand.

But again, if you've got knock under heavy load, I'd be worried about something else. Under those conditions, there is very low manifold vacuum, and so very little vacuum spark advance - essentially the only advance is mechanical then. It's at part throttle where the vacuum rises that the total advance increases and pinging usually happens.

Anyone got any suggestions? How about it might be an exhaust leak at the ports?

[schnerdad]

Ok GWChris, I removed the 925 springs and reinstalled the original springs, set the timing to about 10.5 degrees (I say ABOUT because I find it hard to see exactly straight on through the alt bracket... from my best viewing angle it looks like it's flashing just past the 10 degree indicator...so I'm saying it's set at 10.5)... took her out through the neighborhood, ran it slow, medium and stomped on it..... not near as much ping, I opened all the windows and it seems to have a different sound now though, maybe was'nt ping at all......so figured I check for that exhaust leak you mentioned... sure enough I tried to choke the exhaust pipe and it would'nt die..... noise (ticking) just gets louder and higher pitched and seems to be coming from up in the engine compartment.... I'll get some help tomorrow and see where its leaking and if it is indeed the exhaust I hear at excelleration..I'll run this down before I do the other vacuum modes you suggested... I would like to keep everything pretty much stock if I could for emmissions testing.....Thanks for the input

[waggy401]

<partial hijack> So, with the vacuum connected from Manifold to the dizzy, what should my timing read? I am set at 10* initial w/o vacuum, but when I plug it in (about 20-25"Hg) it jumps to about 30*. Is this right?</partial hijack>

[GWChris]

schnerdad - I was thinking about the springs. I think you are right in that the stops limit total advance, but this is a function only of RPM. You were noticing ping as a function of throttle opening, which could be (and probably is) happening at less than maximum centrifugal advance. So that means that the mechanical advance you had at that point was determined by the springs, not the limit stops. So the springs could well have changed the total advance at the RPM you were at when you were having the ping with load problem.

waggy401 - I'd have to check the curves for the vacuum advance device, but it sounds pretty normal. The vacuum advance just adds to the mechanical advance you have at any given RPM. As far as I am concerned you can run as much vacuum advance as you want without pinging - that is most likely going to be the limiting factor. If you are at high load, the vacuum advance all goes away anyway, and you are left with just the mechanical advance - and since you've got it at the stock static timing, it should be fine.

Like I said, ping will be the limitation, and if it pings just dial out vacuum advance with the allen screw in the advance can until it stops. Then you are running as much vacuum adavnce as you can, and the mechanical advance is still stock (and therefore safe). Works for me anyway.

[GWChris]

One note about running manifold vacuum at the dizzy - I still have all the CTO's and stuff so that I can put the vacuum advance back to ported for emissions testing. Mostly it increases the idle cumbustion temps.

[schnerdad]

Any noticable increase or decrease in gas milage when running it this way (manifold vacuum vs. the CTO Vacuum)????