Ok sometime ago you recommended a Crane kit when i discovered my 73f100 4x was advancing way quick the problem came on very quickely and it didn't take long to discover the problem. I replaced the springs and vacumn pot and everything was great, that was 4K ago.

Recently the truck started running rough after it ran for sometime or in stop and go around town, and got slowly worse. A complete tune-up didn't help, i even unplugged the EGR valve.

Sooo i discovered after the probem got to the point that the symptom were the same as before that i had the same problem, now this was this evening and I have not pulled points plate out but it seems that the crane kit failed in 4K miles, maybe a spring came loose or broke, but now that i look back it appears that the spings were stretching with heat. Well I hope when i replace the spings again with the spares that this corrects all the problems. I'll post again after i inspect the Springs. I'm thinking now since this is the orginal distributer that its time to up-grade depending on what I find.

Any suggestions on a up-grade, the engine is a 360 stroked to a 390 80K miles.

 

I like the DUI setup from: performancedistributors.com $375, but that may be more than you want/need. I like this for it's simplicity and reduced clutter.

The all MSD system that I run will cost even more, but provides a lot of performance and adjustability. Although, I've had failures with almost every piece in the system (MSD 6al, mag pickups, coils). this system has a lot of wires.

probably the most logical option, get a reman Ford dizzy and use your Crane setup.

 

is it the kit with the adjustable pot and springs? I never got mine to work. I ended up buying a reman dizzy, added a bigger cam, lowered the timing. It seems to work better. I just blew another spark plug apart though, so something in my timing is to aggrevise. I know my comp is about 9.4 to 9.5 and that doesn't help me either. I am thinking about having my dizzy custom curved.

Something I have noticed with the durasparks at least is they have 16l and 21l weights. The 16l is giving 32 degrees max plus inital, and i think vacuum advance is pulling so more on top of that. I would like to see something like 10 or 13l weight, so that we can rum more inital for better bottomend power. And of course to more vacuum the engine has the more it pulls as well.

I tried 18 intial with mechanical, in my case, 32 max for a week and my truck had better bottomend and midrange power than with vac advance. Restarts where fine but the only thing I noticed was sluggish just off idle (if thats the correct term). just had to push the gas a little. I noticed this only when the engine was not up to temp but after that there was no problem. I just can't figure why it was doing that. Maybe the engine efficiency was too low at the temp or that combined with to little advance at the rpm range. I set my timing in park but when you put a vehicle in gear the rpm goes down just a little.

Maybe I just rambling on about one of my daydreams, I don't know!

 

yes its the Crane kit W/the adjustable pot and different sping options. I saw the weights stamped but didn't note the numbers.

Well forget what i said yesterday, i changed out the springs and pot(i had ean extra set) even though everything looked good and the problem was still there, forgive me Crane Company.

apparently the problem is heat (probably) and RPM, as it still idled but still cut out with the Vac line on when rpm came up and advance started, but this time when i unhooked Vac to check timing and brought up R's it cut out and the fire went out and wouldn't restart.

I'm guessing now, but i think it almost has to be the coil, i didn't check cause it was dark o'clock. Does anyone have an idea?

the problem started out as just rough running when there wasn't much load on the engine, and after it was driven for some time, and was worse in stop and go driving but didn't get worse for somtime, then it got worse where engine wouldn't run much above idle, but would clear up if engine cooled or i got it out on the highway, now yesterday it didn't improve with cooling but would run without vac line attached, (why i thought is was in distributor) until tonight when the fire went all the way out. I have replaced plugs, wires, points, condenser. This was long winded, sorry any advice is welcome.

 

Well, when the vacuum advance is plugged in, it changes the dwell time of the points. If your coil is going bad, it may need more dwell time to charge up. I would do two things:

1. Get a new coil
2. Get a dwell/tach and measure the dwell angle, and adjust until it's about 28 degrees. Watch it change when you plug in the vacuum advance. You want it to stay between about 28 and 34 degrees.

 

I still have my old coil, I'm gratified that there is always someone who has advice and experience.

I thinking i'll start and see if there is voltage at the + on the coil, then fire from the coil.

Believe it or not this is the first time since I bought it new that it has not run. I've blown the alternator, spun a 3 member bearing way out, but limped in both times.

I'm not getting any mechanical satisfaction out of this!

 

Vacuum advance does nothing to dwell, it can't. Change dwell (how long the point are open, controlled by their distance from the cam lobs on the shaft) you change timing, change timing (when the points open) does not change dwell. Moving the points plate and the points around the cam on the shaft does the same thing as the mechanical advance does, changes when the points open, not how long they are open. The coil can still be bad as when you open the throttle the ignition has to work harder, if the coil is weak you will get a miss. However a bad condensor can also cause this too.

 

I've seen vacuum advance change the dwell angle. When the position of the plate changes, it slightly changes the distance between the points and the cam. This changes dwell. I've seen it happen. At idle, I observe the dwell angle with a dwell meter. Then I pinch the vacuum advance line, and the dwell angle changes. Note that this is with the vacuum advance on full manifold vacuum, otherwise this test would be impossible. It is very repeatable. Moving the points plate cant help but change the dwell angle.

You're not going to tell me it doesn't do it; I've seen it happen. The change of dwell angle in my distributor was about 5 degrees. Varying RPM didn't change it much, maybe 1 degree.

I will admit that it doesn't look like it should. The pivot is on the opposite side of the cam from the points. It doesn't look like the vacuum advance should change it much, but I've seen it happen. It could have just been my distributor, but look at it. Pull enough vacuum advance, and it will start to change dwell.

I'm not trying to be argumentative here; I'm just pointing out what I've seen.

 

Then either the base plate was not centered or the was where in the buttons or the nylon bushing the plate moves on. 5 degrees is a bunch. You shouldn't be running manifold vacuum at idle anyway.

 

You may be on to something with the worn bushings. They were somewhat worn when I took it apart. The plate was centered correctly, the way Ford made it anyway.

If it was the bushings being worn out, then I doubt I'm the only one that this has happened to. These distributors are 30+ years old, and I wonder how many people take the time to put new bushings in? It got bad enough (5 degrees over where I set it) that it would start to burn up points. That's when I got my electronic distributor. In retrospect, I probably could have got some new bushings and it would have worked perfectly.

 

Yep, mine came out in pieces. I also noticed notches in the cap from the rotor hitting. The shaft slid up and down some, had godawful amounts of end play. I had no qualms about a unit replacement.

I guess that splains why the timing walked around so much.

Does anyone know where to find shaft bushings as well as the nylon bushings for the advance plate?

 

OK well it runs again, clalk it up to being careless, but with Vac on dist it cuts out: this problem came on slowly with just missing without a load on the eng, as described earlier but suddenly it wouldn't run much above idle, i have make no progress in my attempts to repair. I have the heavest Crane spings on and initial advance is 750 to 800, at 1400 its 20 degrees, at 1750 its 30 degrees and cuts out completely. With the vac line off the dist it seems to run fine, 20 degrees at 2000rpm, and 30+ degrees and 3000 rpms. If i hold down the throttle it runs really rough and will backfire really loud. Again i have replaced all the tune up stuff including plug wires, and unhooked the EGR valve vac lines, but that didn't help so they are plugged back in.

 

Check for a wire inside the dist. that moves or could come in contact with the points or point wire when the vac adv starts. The point plate might be grounding out when it rotates with the vac movement. It might also be loose enough to cause wide variations in the dwell.

Double check your spark plug wire order ans routing...we've all made mistakes in that

 

Well thanks for all the help, but it turned out to the the vac pot itself. the pot is adjustable, but the directions gave me the impression that it only controlled Max advance, when in fact it controls the speed of the advance. So out of frustration after turning the adustment out prior, i turned it out all the away and the probem was cured, it didn't die anymore above 1750 r's. The test drive went well and the 390 ran strong. the Crane instruction indicated the initial advance at 800 and full at 3100 (about) but after i adusted it to the max (slowed advance) it still doesn't Max out until about 4200rpm's. I think now i'll just start turning the adjustment back in to compare the performance.

So looking back i think that the spring in the pot was factory adusted just enough for the engine to run good when i first put it on, but over time engine heat and fatique make it run rough and finilly allowed the vac to advance to far to fast to where i lost spark. that may not be it, but it sound OK. Anyway after replacing plug wires, plugs, points/condenser, rotor, Cap, and fuel filters i pretty well set.

Thanks again.

 

Did you check the relationship of the rotor to terminal post (cylinder to fire) at time the points open? Dizzy one tooth off and advance pulls rotor away as rpm's rise?
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