Timing issues...distributor advance?
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No, I was connecting vacuum to a ported or timed vacuum. I will have the recurve kit tomorrw. I'll give it a try and see what happens. I'm anxious to see which weights i have in the dizzy. I read if i have to reverse the weights, it moves the timing 180? Is this true? Never saw that posted in the instructions.
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well i put in the Mr. Gasket recurve kit today. I used both the springs. The advance mechanism in my dizzy had a 16 and a 21. It was already on the 16 so that was the best i could do. So now I know I'm going to get 32 degrees of advance from the mechanical. I set the initial at 12 degrees for a total of 44 degrees. That is too much total by all indications. The truck idles great and runs great while accelerating and at WOT. I cannot hook up the vacuum advance because it immediately starts backfiring from idle at full maniflod vac. On the timed vac. it idles fine (obviously no vac at idle.) but as soon as you add any load at all it starts backfiring. It continues to run rough at all but WOT. Without any vac advance it runs the best but studders under cruise conditions. I'm at a loss here. HELP! BTW the recurve kit di help alot. Under WOT it screams! Pulls hard way past where I want to drive. It was still pulling hard at over 100 mph!
FTE Emeritus
Joined: Jan 2006
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From: springfield Missouri area
I am trying to dig up all my lost brain cells. If I remember right the vacuum advance on the fords has an adjustable screw inside the nipple where the vacuum line goes. It is set with an allen wrench. Not sure how it needs to be adjusted though. Don't shoot me if I am wrong on this one though. It has been a lot of years ago, Might try to adjust if it has the screw. Can't find my engine manual for the 78-79's. Haven't had to look anything up in it in a loooong time.
You might also try to adjust timing with a vacuum guage, That is how we used to do it for max power. Advance the timing until you get the highest vacuum reading and then back it off one inch of vacuum. If it is not hard to start you are real close. The vacuum line should definetly be on a ported vacuum on the carb.
You might also try to adjust timing with a vacuum guage, That is how we used to do it for max power. Advance the timing until you get the highest vacuum reading and then back it off one inch of vacuum. If it is not hard to start you are real close. The vacuum line should definetly be on a ported vacuum on the carb.
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I did try adjusting the vacuum advance but was just blindly turning in and out a turn or two. Never really felt much difference. I think I'll try setting it with the vacuum guage today and see where I am at that point. I may alsos order an adjustable vacuum advance just to be sure I'm getting some adjustment there. It acts as if its pulling way too much timing with the vac advance hooked up. especially bad when you first crack the throttle. It pops an backfires until you lay into it pretty hard. Then when you let off to "cruise" it starts the backfiring or studdering again.
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From: springfield Missouri area
I guess you tried checking for vacuum leaks and such. Fresh engine right? Did you shave the heads or put on adjustable valve train? Plug wires new or old? Did you try posting on the engine thread? Might be more expertise there.
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Engine is not fresh but cam, lifters(edelbrock) timng chain, intake and carb are new. Dizzy is new(rebuilt) new fuel pump new tune up parts( wires,plugs, cap and rotor). I'm gonna play around some more with the vacuum advance today. I think I'm turning it the wrong way. Also gonna try the timing with a vacuum guage thing!
Post Fiend
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From: Big Sky Country
You may want to give this a read...FORDMUSCLE webmagazine: Timing is Everything - Distributor Curving for Maximum Power
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I had a similar issue once due to a vacuum leak on the intake manifold. I never messed with the timing, however I had all the symptoms you describe. Ran like hell at wot but popped like the 4th of july cruising and accelerating from idle.
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I did read the article you posted the link to.! Thanks Montana HighBoy. I never considered the intake mainfold leak possibility. I guess I just assumed because it ran so good, that could not be an issue. I reallly don't think thats the problem because at idle it holds 19 hg on the vacuum guage and is steady as a rock. Idle is perfect(without any vac advance) and is steady. no surging etc. But I will shoot some carb cleaner around the intake to make sure.
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If you think about it this way it might make more sense:
The distributor is advancing under load, and so much so that it is igniting the mixture before the intake valve closes. I would shoot for 34 degrees total timing, all in by 3000 rpm. You may need to add some material to your 16L slot by either welding some metal onto it or cleaning it up really good and soldering it to the desired gap, then fine tune it by filing the solder or weld down to get your gap perfect. a 10L gap is more what you will be shooting for and I believe it is in the range of .480 - .485 inches. use an inside caliper to measure it.
The distributor is advancing under load, and so much so that it is igniting the mixture before the intake valve closes. I would shoot for 34 degrees total timing, all in by 3000 rpm. You may need to add some material to your 16L slot by either welding some metal onto it or cleaning it up really good and soldering it to the desired gap, then fine tune it by filing the solder or weld down to get your gap perfect. a 10L gap is more what you will be shooting for and I believe it is in the range of .480 - .485 inches. use an inside caliper to measure it.
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Well I finally got a tach hooked up under the hood. I think I have discovered a major problem. with no vacuum advance connected, the centrifical advance does not move the timing at all until about 1800 rpm. By then th engine is falling on its face. Then it moves nice and smooth from that point til about 25-2800 rpm where it tops out at about 40 degrees total maybe more but my timing marks don't go that high. Basically the timing is not coming in soon enough. I did the Mr. gasket 2 spring kit but i guess I need lighter springs still? where can I find these? So until I can get th mechanical working properly, I don't need to worry about the vacuum advance.
Post Fiend
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From: Big Sky Country
If you're using the 16L advance slot you probably don't want much more than 4-6* of initial otherwise you're risking detonation (pinging) have you tried backing off on the timing and connecting your vacuum advance?
