Yeah, I'm using a timing tape and I've tried initial timing with it at different increments between 9 - 12 and the vacuum advance pulling it into the high 30's with heavy springs. I think the vacuum advance canister is just busted or defective or something. This is the third one on there too... I had the stock one which wasn't adjustable and just ran the engine horribly. Got the Summit HEI rebuild kit and the vacuum advance's diaphragm ripped or blew out and then got an Accel adjustable diaphragm and at it's lowest setting it seems to be the same as it's high setting almost. The only time I start idling worth a damn is starting at around 16* and even there it's asking for more timing to even out.

I just realized that I only said that it does this under load. Well that is true but it has to be around 3/4's throttle or above from what I can tell. It only does it a little past 3000 rpm's at 3/4's throttle and at full throttle it's very noticeable at 3k.

I've been gone for over a week on vacation and if I can I will just start from scratch on timing one night this week. Pull the distributor and go over it from top to bottom and put everything in a conservative mode (i.e. heavy springs, lowest vacuum setting on the vacuum advance, low initial timing). Who knows... maybe I even sheered the pin in the distributor gear.

 

O.K. So since it's only like a 5 min adjustment I went outside and dropped the timing down to 12 again and hooked up the vacuum advance and when I got to around 4000rpm's I'm hitting 40's in timing. Disconnected and took it for a spin and it STILL pops and I'm only getting into the high 20's on timing when I'm using the timing light.

I'm thinking that maybe what I'm hearing is that the valves aren't closing at high RPM and maybe I'm having valve flutter. I'm not sure. Maybe when I redid my rockers I over tightened them and the valves aren't closing all the way.

 

You don't think I'm running too rich at this level and the popping is fuel detonating in the headers do you?

 

Considering all the farting around you already did with the timing, something else must be the culprit. That would be assuming your timing is staying advanced and it isn't bouncing around. But you haven't found anything to suspect it's doing that. There are only a couple of things that come to mind which would give you an exhaust sputter, misfiring ignition or valves. One down...one to go? Unless there's still a hidden electronic overload issue with your ignition system?
If it was a fuel delivery problem, I would expect the engine to be bucking or bogging on you.
So, it's quite possible you're experiencing valve float. What procedure did you follow when you adjusted the valves?

 

Well, the heads are still stock and were what I was going to get until the transmission came up. I really suspect some problems with them.

The valve procedure I was doing was, while the engine was off, was to bump the ignition with my remote starter until the intake valve started down then do the exhaust. Then reverse the procedure with the exhaust and do the intake valves. I would usually do a 1/8th to 1/4 turn and after locking the poly down. The way I would determine valve lash is that I would rotate the push rod till I felt it tighten and when it took the slack out of it moving vertically up and down length wise. If there was any clatter with the engine running I would tighten them while it was running.

I guess I'm going to be pulling the valve covers again and redoing them next. I recently installed the Isky anti-pump up superlifters and comp cams magnum pushrods.

I've also been looking at other forums and this one has a similar problem with a ton of suggestions...

 

Jeez....just about the only thing that wasn't mentioned there as a possible fix was to check the tire pressure!
When checking for zero lash, I've had some inconsistencies using the "spin" method with the pushrod still feeling easy to spin even though I know I'm too far tight. Now I just pull and push the pushrod up and down until there's no more movement.
Since you're doing the one-on-one method, have I shown you this before? http://www.centuryperformance.com/ad...h-spg-149.html

 

Yeah, I've seen that page a couple of times before but I keep forgetting to bookmark it each time I see it until now. I just tried the alternator fix that the original poster did in that thread and I can't tell if it worked or not. The reason I say that is that I only had it happen in the low end and there was a slight hesitation when it happened and when it did happen it wasn't but one or two pops. I think the hesitation is from the huge fuel dump I have going on right now with the secondary metering block and I don't know if that's causing a slight pop or something also. Then when I plugged the two wire connector back into the alternator it seemed to return but it wasn't as bad as before. I'm wondering if it's just because the engine was warmed up that it's not doing it as bad. I'm going to let it cool back down to a cold start and take it out again with the alternator wire disconnected and see if that's the culprit. It sure seemed to be running a little better also. I know where and when I'm at a certain RPM and speed and this pass with it off I was 5 mph and 500 rpm higher and the popping was gone.

 

O.K. totally redid timing and it seemed to help. Pulled the distributor and took everything down to parts almost and put it back together. Set initial timing to 12 with a mechanical curve to 32. I found out that the port on my carb is apparently one of the special emissions ports that you're not supposed to hook to for vacuum advance. I found an article on it on another site where someone was having a similar problem with no vacuum advance at idle but was getting it with RPM climb which mine was doing. So I re-blocked it off and put it to manifold and viola! I now have correct vacuum at idle with the mechanical curve taking over through the RPM climb. I don't have the popping near as bad but it's still there just a teeny bit. I will do the final nailing down of the timing over the next few days to see if I can get it to where it needs to be. For some reason I still don't think I'm hitting my full potential of advance before it pops. I'll redo the valve lash too one night this week and see if that helps. I did the driver side and a friend did the passenger side and I think he over tightened his side possibly now that I think of it. I still think I have a problem with the driver's side head on cylinder 1. I think one of my valve seals is leaking and I get a little bit of smoke on start up. I don't think it's a ring since it does it on start up which makes me think oil is slipping by the seal when the engine is shut off and gravity pull the oil down towards the pan. Then it congeals on the piston and takes a minute or two to burn off. Gotta love 35 year old heads even when they've been rebuilt. :\

 

O.K. So redid the valves, redid the timing and it still does it. A friend gave me an MSD distributor and external generic coil. Hooked it up to my MSD Streetfire box and it fired up without a problem. I measured all the voltage points that I could on this and everything read 12v like it should but the coil connections. The pos and neg connections read 2-3 volts at idle and 5 volts wide open. This is with the positive lead on the positive terminal and the negative lead both on the negative terminal or a body ground. All readings were consistent. I'm thinking that the ignition box is at fault since these leads come from it. I thought about jumping a wire directly from the battery to the positive terminal on the coil but I'm afraid that will blow the coil/ignition and void the warranty possibly.

What voltage should the terminal posts on the coil be reading? I never checked the connection with the HEI where these points connected before since they were internal in the cap.

 

I'll take some readings off of mine for comparison. I'm running an MSD 6AL box, coil, and pro-billet distributor.