What the PING !!

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  #1  
Old 07-19-09, 01:55 PM
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What the PING !!

Have a 1969 Ford F-250 with a 390 ci, 4 bbl crab,point dist, auto trans and no smog components. When driving at about 60-70mph up a slight grade the engine will ping . Using 91 gas and set the timing at 4 degrees btdc still noticeably pinging.. Going up the same grade at 40-50mph no noticeably pinging . Love the truck ,hate the ping . Any suggestions would be greatly appreciated Thanks Joseph
 
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  #2  
Old 07-19-09, 02:37 PM
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Ford 428 s were bad for pinging, too. And it's not just the sound, it's the damage preignition will do.

You can turn the timing back some more for your base setting. Too far and it'll start more difficult. Or you can try gasohol, if available. The alcohol in it will modulate the combustion speed and may take care of it.

You can put in additives from the auto parts store shelves and boost your octane much higher = may/may not work.

You can change your advance curve in the distributor, by changing the springs and flyweights. You may actually get it killed by doing this if you can fool around with it enough.

You can run carbon cleaner additives through it to get rid of any hot carbon. Also go to a cooler plug. sometimes the spark plugs contribute to pinging with a hot tip.

Or you can go to richer main jets = little richer = little cooler combustion temperatures.

Or you can go to a performance exhaust to cool combustion temps = sounds better than the good it would likely do.

After you get it cleaned up, the ignition modifications and the the richer jets would probably do the most good.
 
  #3  
Old 07-19-09, 02:49 PM
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Ahhh ..the good ole days of Carbs and Points......

Super simple and cheap.... try pulling the vacuum advance hose off of the distributor... Cap it and take the car for a ride......You may lose a minimal amount of power from a dead stop, but the extra advance can be eliminated without changing actual design charachteristics....

Also , look carefully for a vacuum leak.....it can lean the fuel out to the point of detonation, without being readily detectable or causing any other driveability symptoms.

If all else that has been mentioned fails....Your going to be stuck going up a grade on the Gasoline..... Unleaded fuels are no where close to the Leaded Dinosaur sweat that the vehicle was designed around, and it is not uncommon for old V8's to require 93 or 94 octane fuel....
 
  #4  
Old 07-20-09, 06:27 AM
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On most of the old vacuum advance diaphragms they are adjusable by putting the right size allen wrench in the port the vac hose slips onto and turning a screw inside which changes the spring tension to change the vac advance curve. Using a tach and timing lite, you can chart the curve and change it. As another poster said, changing the cent. springs may also be needed. I had to do this w/ a 429 w/ 11:1 comp ratio.
Good luck,
Mike
 
  #5  
Old 07-20-09, 04:54 PM
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Originally Posted by mla2ofus View Post
I had to do this w/ a 429 w/ 11:1 comp ratio.
Good luck,
Mike
And you probably spent alot of time behind the local airport looking for Gas

Problem with adjusting a vac advance diaphram is simply AGE....
9 times out of ten if the Canister has never been disturbed..doing so will destroy it. If it wasnt so old, I would absolutely agree with Mike.Thats why I suggested just unplugging it. If you Break a vacuum hose....No big deal...Break the canister and you will be spending 6 months tracking one down, and committing your first born child....
Back in the day I ran Big block Chryslers, and scrounged the Bone yards for the later electronic set ups...Night and day difference over the points......Im not to KEEN on Vintage fords, But if you can find an Electronic distributor and Ignition module that will "Retro" into your truck, you will probably be Much happier. ???460 Truck Motor perhaps????? I know they were produced until the mid eighties in carbureted form ( The later ones that are fuel injected use a different design for ignition and are not even close to useable)..
 
  #6  
Old 07-25-09, 08:56 AM
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ping

Just for info I had a 1970 GM van 6 cyl that the owners manual called for 93 octane.
 
  #7  
Old 07-27-09, 10:29 AM
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I would give it a good cleaning with seafoam, if its never been done it may take 2 treatments then go with a colder spark plug and see if that healps.

What is the engine temp on your truck?
 
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