Part throttle ping, CANT FIND IT!

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Aug 7, 2007 | 09:45 PM

gearhead351

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Part throttle ping, CANT FIND IT!

I have an 84 Ford F250 4x4 with a 351 windsor. Ive recently put an intake/carb, cam, roller rockers, headers, GOOD wires, cap, rotor, plugs, coil, MSD ignition components, etc.... I dont know when the pinging started. It only pings at around 2500rpm and i think up (I cant hear it past 3000). Ive nearly backed the dizzy off almost a half turn! STILL PINGS! So maybe I need a higher octane (Was using just 87) I tried 89 still pings! The motor in the truck is not original I dont know where it came from My grandfather had it put in when the old one blew. What would cause it to ping at 2500 and up!? It doesnt ping below that. The pinging doesnt get worse when the dizzy is cranked up. What is causing this? It is a mechanical advance distributor. How can I tell if this is actually a high comp. motor? It had Nylon timing gears in it. Where are the vin #'s? Can I check the history of where it came from?

Thanks, Matt

Aug 7, 2007 | 10:41 PM

Franklin2

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From: Virginia

Do you have a aftermarket temperature gauge hooked up? If not, I would hook one up and see what temperature you are running at. If it's running a little warm, this will cause it to ping.

You also need to get a timing light, and see what the timing is actually set at. Around 8- 10 BTDC should be a reasonable setting for your engine.

Aug 7, 2007 | 10:48 PM

gearhead351

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I have put after market guages on it, it runs at about 208 all day. When I checked, that was what I set it at was about 8.

Aug 8, 2007 | 08:45 AM

Franklin2

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From: Virginia

Take the vacuum line off the distributor and plug it. Then see if it goes away. If it does, then you can try a allen wrench stuck up into the vacuum line nipple in the dist, and see if you have an adjustable vacuum advance(some were from the factory).

Or, you can try what I did, which fixed mine. I have a 351w 2bbl engine out of a 79 cougar. Everything was fine till I put headers on it. Then I got pinging, especially if I had been running down the interstate. I found my egr quit working right because of the headers(no backpressure) so I jetted the carb up a little and put cooler plugs in it. Nothing really helped till I put a 180 degree thermostat in it. That's what seemed to fix it.

Taking the vacuum line off will probably make it go away too, but you can experiment with the other things. If you keep running it, I would run it with the vacuum line off to prevent damage to the engine till you get it fixed permanently.

Aug 8, 2007 | 08:10 PM

gearhead351

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Thanks, but I dont have a vacum advance dizzy, its mechanical. I eliminated the egr and all the smog stuff a long time ago. It also has a 185 thermostat. I found that it only pings at 2500 and up and only when the engine has been ran for a few minutes I think when the water temp is about 120. I think it might be carbon built up on the piston. Hot spots maybe? What is the BEST way to get all the carbon out? Ive tried seafoam. If I remove all that carbon some way, Will it affect anything? (i.e. compression)