I know this isn't actually a Maverick question but it is Ford. My 82 F250 w/400m died today. It cranks but won't fire. The distributor rotor spins but stutters each revolution at the same place. I had a guy tell me it was a bad timing chain. Could it be a bad distributor gear instead? If the timing chain was bad enough to skip that much wouldn't a valve hit a piston real quick?
Distributor Could be either or of the two. Pull the dist. out and look at the gear for signs of bad teeth etc. Also check to see if the roll pin that holds the gear is not sheared, you can look into the hole and check the teeth on the cam also. Check for excessive wear of the shaft in the distributor housing(wobble). Do you have any spark at all? Put a rachet and socket on the crank balancer bolt and rotate slowly to see how far the crank turns before the distributor rotor starts to move. This will tell how much slack is in the chain. Just a few suggestions to start with. Good Luck
I yanked the dist and didn't see anything wrong with the gear. I had the crank gear at TDC but the dist was pointing about 120 degrees from #1. At that position I was not able to see any damage to the cam dist drive gear. I also appear to have about 20 degrees of slop in the timing gear based on crank rotation without moving the rotor. Obviously the timing chain needs to go. I should have it out tomorrow. Hopefully it is just that and no damage to the cam.
If the timing chain skipped, it usually wont hurt anything in a 400. They are low-compression motors and the pistons are usually so far down in the cylinder at TDC that even if the valve was fully open, it still wouldn't hit. Not to say they're bad engines...in fact, they have great potential (but a bad reputation)
The plastic teeth that ford put on the cam gears back then will just crumble after a while . To make sure why dont you line up the crank with the distributer again and make sure that the its not something like a failed pickup coil . Or something in the distributor that is binding every rev . If it all checks out then pull off the timing cover .
The problem was the timing chain and cam gear. The cam gear appears to be aluminum and not nearly thick enough for the chain. It was only about 2/3 as thick as the replacement I bought. Another strange thing was the crank gear seemed to be on backwards. The little mark to show TDC was facing the block. Now that I got it all back together it seems to run just fine. When I had the distributor out I did check the gear, pin, shaft, etc. No obvious issues with any of it. Thanks for the help.
