Ok well I bought my 86 f250 little over 3 months ago for a winter rat so I don't have to drive my 94 f250 long story short the ad said "noisey lower end" drove it home sounded more like a ping it only did it at crusing speed let off its gone step on it hard gone but a crusing it is clearly there. I treated it like a ping heres a list of what I have done so far

New plugs
New wires
Cap and rotor
New oem coil
Checked timing set it at 10* spot on
Filled it with 93 octane
New carter afb 600cfm
1inch carb spacer to get rid of the egr spacer
Checked oil pressure 50psi on start up cold 35-40 warm
And a few other odds and ends after all this same exact problem!! But if I unhook the vacuum advance and plug it the noise is gone and the truck seems to run great no bog or hesitation but still doesn't have all it could cuz it runns much better with it hooked up and gas mileage is down the drain with it un hooked I can't figure it out any Input would be great and sorry for the lack of grammar I'm using my phone

 

It also should not be lean I tried 50 all the way to 68 main jets in the factory holley before replacing it.I though I had it at one point when I replaced the timing chain cover gaskets I found the fuel pump wore out beyond belife this thing had to have all most a inch of play in the arm but still didn't do the trick she's got me stumped

 

My thoughts are that if there is no knock at heavy load/full throttle - but there is at light throttle, the vacuum advance is putting your timing way too far ahead (there's no vacuum advance at full throttle); some advance units are adjustable.

It's possible that the centrifugal advance is excessive but doesn't show up until vacuum advance is added on top.

If the EGR was disabled/removed & causing the ping, then enriching the mix (as you did) would have at least improved the problem.

 

Did you unhook and plug it when you checked, set the timing?

 

If it's detonating with the vacuum advance hooked up you have too much vacuum advance. Figure out how much it will advance, let it idle and either use a vacuum pump on it or put it to manifold vacuum and see how many degrees it's adding. If not adjustable buy an adjustable one and limit to where it won't detonate.

 

Been down this road before. Your main problem is the EGR is not hooked up and functioning. Even if you did hook it up, if you have any type of free flow exhaust, it still won't work correctly.

The vacuum advance units on these trucks originally do allow a lot of advance. It's how the engine was set up for emissions from the factory. Now the engine has been modified, everything is out of wack.

On one engine I used to have that had this problem, I left the vacuum advance disconnected and bumped the timing up to about 14 degrees. It ran very well this way, and I was planning on getting a adjustable vacuum advance unit for it. What I did in the mean time was to drill a hole in the vacuum advance where the arm went through, and then I put different diameter pins and nails in the hole and this would limit the total advance of the unit.

On another engine I had, I wanted to keep the timing at the stock spec. I got the EGR hooked up and it helped some, but I still had some pinging. I found out the EGR works on exhaust backpressure, and with the headers and dual exhaust this was messing the egr up a little bit. So then I started experimenting with the jets in the carb like you did, and went up two sizes. It ran a lot better like this, but it still has some pinging. What finally got rid of the pinging on that engine was to step down to a 180 degree thermostat in the coolant system.

 

I can't even set my base timing at 14* and it still seems to ping i have it at 12* with no ping.what temp thermostat do they come with form the factory?

 

I believe it's 192°F

 

Could that be enough to cause my ping I haven't changed the t stat and the truck was sitting for 3 years before I bought it

 

On an unrelated note, why are you using 93 octane?

 

Your ping is caused by the EGR not being hooked up and functioning. If you refuse to hook it up and get it working, then you will have to play with all the different things I listed in the previous post to try and get rid of it.

In other words, your truck is not broke. If it was all original and hooked up like it's supposed to be, then it would be broke and something would have to be replaced or repaired to fix it.

You can set your timing at 14 degrees IF you leave the vacuum advance disconnected. If you turn the timing back enough to get rid of the ping with the vacuum advance hooked up, then the engine doesn't have any power or throttle response.

 

Just filled it up once with 93 octane I usually just run mid grade witch is any where form 86-89 octane around here.

So I guess I'm going to go buy a adjustabe vacuum advance mine doesn't appear to be adjustable and 180 t stat.

Would spark plug hotness or coldness affect a ping when I bough the spark plugs all they had in stick was copper core champion's I figured they woukd be better the the Bosch plugs it had

 

The egr is not a option at this point either with the spacer on and the dual exhaust with cherry bombs and carter carb so seems like just some fine tunibg at this point

 

You will get it. Just keep messing with it. I was surprised how well the 180 degree thermostat helped my truck. But they are all different, so something else might bring yours around.

 

Yeah I think its slowly getting there.I'm gonna make a run to napa in a few and report back