I have a 72 f250 camper special, and I put a 390 from a 76 Ranger in it. I've put it all together and now it won't run on the correct timing. I've tried all sorts of gaps but it doesn't help. I'm using the distributor from my old 360 because the dist. from the 390 is all electronic and I don't know how to wire it up. My truck will run but only when the rotor in the dist is pointed at plug 5. I have no idea what to try next, I'm lost.

Kellen.

 

Kellen, Welcome to FTE the nations #1 online Ford truck tech support site.

Your distribitor may be 180º out. Another of our members may have a better answer for you.

Glad to have you aboard.

John

 

Thank you for the reply. I tried it at 180 deg from where it is now and it backfired worse. When I went to get the correct timing I cranked the engine with the first plug out and half of a two part compression guage in and I put it on the timing mark where I got a vacuum at top dead center. I'm really lost.

Kellen.

 

Make sure the truck is in park, pull the coil wire so it can't start.
Pull the #1 spark plug out (front passenger-side plug). With your thumb over the spark plug hole slowly bump the engine over by jumping the solenoid, until you feel/hear the compression blast. With a breaker bar on the crank bolt, slowly rotate the engine forward until the TDC mark comes up. You are now at TDC compression stroke on the #1 cyl.
Remove the dist. cap and see where the rotor is pointing. It should be pointing at or before the #1 spark plug hole on the cap. If it is not you may have to pull the dist. out and reposition it.
Wire the plug wires counter-clockwise, 1-5-4-2-6-3-7-8
Set timing with timing light.

 

Thank you. I did all that to test that I'm not 180 off. Then when I position the rotor pointing at plug #1 it won't run but it backfires. Then if I moved the dist. until it runs, rough but running, when I took off the dist cap the rotor pointed at or just before plug #5.

 

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ok, so I got frustrated and changed the timing around 180 because: I pulled off the valve cover on the 1-4 pistons. I turned the crankshaft again until the intake valve went down and then the exhaust valve closed as well. Then I looked at the rotor on the dist. and it was 180 deg off(I think). I'm not sure that its correct now though. Now that its where its at, I still can't get it to run. It backfires, and it won't start. I don't know what to do.

 

Did you hear the engine run when you got it?
When both valves are closed, is the number 1 piston all the way to the top?
Where is the timing mark?
The timing chain could have jumped a notch to get the timing off.
Factory chains have a short life of around 100,000 miles because they are put together with plastic covered cam gears.
My 70 had that problem when I got it and it was at 99,000 miles.
Don't get too frustrated with it. take your time and check everything thoroughly.
Good luck.
Ken

 

If you have the valve cover off, rotate the engine, watch the intake valve on the #1 cylinder (never mind the exhaust valve). When the intake valve closes, the next time TDC (0) comes up on the crank pulley (at this point it should be at TDC), you are on the compression stroke. This is when you want the dist. rotor to be pointing at or before #1 on the cap.

 

Spark plug gap should be @ .035".
Set Point gap at .019" then reset engine timing.