i was drivig down the road trying out my new radio and i got a very violent backfire and it quit and is not even trying to start. i was hoping it was just the rotor but it is intact. the distributor is turning but i did not get a chance to see if i have spark or not. what do you guys think? timing chain.......... no don't say that!!!!!!!!! gotta be something easier.

 

Change the oil and look for plastic timing gear teeth.

John

 

Also you could bring your engine to TDC and see if the rotor is pointing to the number one cylinder position on the distributor cap.

 

Try checking for fire to your plugs. Sounds like you might have blown the Ignition Module Maybe. But the other guys are right too. The backfire and sudden dealth of the 460 could very well be Timing Gear Failure. How many miles are on the engine?

 

rebuilt a few thousand mile back per the po. i will check for spark and go from there.

 

well...bad news it got spark so it is probably distributor or valve timing. if i have plastic in oil is that a distributor drive gear or timing gear?

 

If you find plastic in the pan its from the timing gear on the camshaft side. The easiest way I know of to check if its the timing chain is to pop the distributor cap, put a socket on the crank bolt, turn the crank as you watch your rotor. When it starts to turn stop and turn crank in the opposite direction slowly. If chain is bad or gear is broke you will be able to move the crank without the rotor turning. I'd say if you can move the crank more than an inch your timimg set is fried.
Good Luck and let me know what you find out!
Larry
1984 F250 4x4 - 460

 

"acceptable" slop in timing chain is 7 degrees according to my haynes. Don't really know how that would translate to inches tho.....

For a quick visual (mirror and doublejointedness great help for this) remove fuel pump or hole cover if electrics and take a look, you can stick your finger in there and actually feel the cam gear. If the teeth are sharp enough to hurt then it needs replaced.

Dart

 

well i tried turning the crank both ways and there is almost no slop .....maybe a 1\4 of an inch but that doesn't mean it didn't "jump time" i will have to pull #1 plug tomorrow and see. this rig has a holley projection throttle body fuel injection. is there anything on the fuel side that could cause a large backfire and stall?

 

I dont think any of the 460's came with a nylon timing gear, only the 302, 351

 

My 77 460 had a nylon coated gear, at least it did before all of the nylon fell in the oilpan and jumped 2 1/2 teeth. The chain was actually on the top of the cam gear teeth when I tore it down. It still ran and got me home from downtown (about 20 miles), but anything over about 1/4 throttle was useless. It wouldn't have pulled a leaf off of a tree.
Jimmy

 

Yep, I also have a spare 460 from a 77 Lincoln that has the nylon covered cam gear as well.


djmac
I would still check the rotor postion with the engine at TDC, that way you can establish whether or not its not a timing chain issue.

 

is the passenger side front #1 cylinder on the 460?

 

Yes

 

the plot thickens......... the optimist that i am i poured fue down the air horn to see if the backfire came from a lean condition ie fuel pump, filter clogged etc and it started right up! i am going to replace the filter and the prefilter and see what happens. i don't know what else could have happened to make it backfire like that and quit except the ignition. all i know is almost anything is better than the timing chain.