I need help!! 460 explodes and won't run!


I have a '77 F350 with an '82 carburated 460. The closest thing to a computer is the ECM. There are no air pumps. The engine had a full rebuild 10K to 20K miles ago and it ran really well until I put it into storage about 2005. The carb is a 4180C single with vac assist secondaries.


Now for the problem. I got the truck out of storage last fall. A compression check showed all were uniform and OK. I got it started and was pleased with how well it ran.....not perfect, but pretty good. I drove it 120 miles to a new storage area for the winter. I noticed that it was over-fueling (about 6 mpg or less) but I figured I could peak it out later. This spring it started right up and although not peaked out it ran well enough to cruise at 65 or 70 mph. After about 75 or 80 miles, I stopped for gas and again noticed poor mileage. After that fuel stop, the nightmare began.


I was doing 70 mph when it started coughing and sneezing and violently backfiring like crazy. This lasted for a few minutes no matter what i did with feather-footing and playing with the choke. I was down to about 40mph when it smoothed out and I went back to 70. Long story short....it did it two more times and wasn't running very well by the time I got to the old storage yard. At the yard, the fuel filters were changed and the tank and lines were cleaned but it still wasn't running very well.


The next day I changed the ECM with no noticeable improvement. Changing the coil seemed to make a big difference. I re-did the timing and felt it was running really well and took it out for a road test. A couple blocks and it was snorting and backfiring so badly that I couldn't keep it running. My wife had to tow me back with her Toyota mini-van.....how embarrassing! On the way back I used the clutch to get it running and it was good enough to maneuver and park with a couple of coughs but no backfiring.

Next, I pulled the plugs and ran another compression check.....all OK, nice and uniform and nothing unusual with the plugs. After that, I tried to start it with absolutely no response. I found that the two-wire coil connector had been knocked loose. Fixed that and hit the starter. And that SOB blew up! It was like a double barrel 12 gauge going off and I thought I was "a goner"! It blew the dip stick and PCV about 10 feet out onto the gravel. It also blew the seals out of the valve covers and really messed up the bottom sealing edge. The pan looked OK.


I usually like to use a remote starting switch when working under the hood. My shorts and I are very glad that I didn't use one that day!!


After that episode, I pulled the carb and had it rebuilt. The only real problem was that the secondaries were hanging up open. This would explain the original high mpg and not being "peaked out". But it would not explain the snorting and violent backfiring. When I got the carb back on, I started it and almost had it warmed up (it was not running very well at all) then it quit. I was going to restart it when I noticed flames coming out of the carb! By the time I got out to smother them, they went out on their own.


After about 10 minutes of head scratching, I went over the distributer which was new a year ago just before this nightmare began. The only thing I could find was what looked like tracking inside the hollow at the top of the rotor under the spring metal coil contact. I know! Tracking? From where to where? I replaced the rotor, the cap, and the adaptor ring and tried to start it. Nothing. About 5 seconds later, I saw flames again! This time they were about 6 inches or higher and I had to smother them. I'm sure glad I had the carb rebuilt!!


Only one thing left that could cause this mess.....cross firing! So, I put on all new plug wires. All I could get was what I call "giggling". The engine sounds like it's trying to run but when you quit with the starter, it "giggles" to a stop. More head scratching, but at least no fire.


I checked the firing order and checked to see that the rotor was actually pointed to #1 plug wire when #1 piston was at TDC. All were OK.

The next day, I poured a little gas (about 1/2 inch in a carrot can) down the choke side of the carb. Maybe after the fires, "somehow it wasn't fueling". After I poured in the gas I got into the truck (still not using my remote switch.....I may be dumb but not totally stupid). I closed the choke and hit the starter. I heard a little something.....then nothing.....just turning over. I stopped with the starter and, about the count of 4 after I quit, that SOB blew up again!

I had spent a couple of hours salvaging those valve covers and this time they were really messed up and it took me at least 10 minutes to find the PCV and dipstick.

So that's where I'm at. I could start over with another compression check and whether I like it or not I'm going to get another chance to look over the rocker arms and valve springs. In all reality, I'm lost. I'm punching in the dark.

I'm 79 years old and have worked on 1 or 2 engines over the years starting with a '57 Triumph sport and on up thru various trucks, farm combines, and tractors finishing with 4 Ford 460's with 2 of them fuel injected. But I have to admit I am stumped with this one! I'll take any suggestions that you Ford experts can come up with. In fact, I'm so desperate, I'll even take suggestions from Chevy guys and even Dodge boys. Please don't bother suggesting a large sink hole or a quarter stick of dynamite......my wife already has those.

By the way, this truck is under a fairly nice chassis mount 12' camper so junking it out would be rather difficult.

Thank you in advance.