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Distributor was taken out without referencing anything. Does it matter which way the vacuum advance diaphragm points on a 1977 391 Ford engine in a F750 crane truck? Not sure if picture has correct alignment. PO said truck backfired. What is a good/easy replacement distributor/conversion for the stock points dizzy?
I don't think position of vacuum diaphragm matters on any vehicle. Just put that where it's convenient. Aiming the rotor at the correct contact inside the cap is what matters. If you didn't check that alignment before removing the distributor then you'll have to reset. I like to bring #1 piston to top dead center on the compression stroke and aim the distributor rotor to the correct contact on the distributor cap (the contact that's connected to the plug running to #1 cylinder). Then verify the plug wires are connected based on the firing order.
While I am not crazy about the way the vacuum advance is pointing, if it runs that way, leave it as it is. The best thing to do would be a Petronics electronic conversion to eliminate the points and condenser. That would make it easier o start as being a crane truck I bet it sits for long periods between jobs.
I feel there may be a severe lack of understanding on how a distributor works in this thread.....
I can't explain it without going into a whole bunch of engine operations.....
For someone who is usually helpful, I don't understand your rather cryptic comment. I'll say I don't see how f5fordgirl can see if the wires are connected to the dizzy correctly without seeing which plug they're connected. That, and based on the picture, no one can see where the rotor is pointing.
For someone who is usually helpful, I don't understand your rather cryptic comment. I'll say I don't see how f5fordgirl can see if the wires are connected to the dizzy correctly without seeing which plug they're connected. That, and based on the picture, no one can see where the rotor is pointing.
The plug wires are marked, they are in the right rotation and order, 1 5 4 2 6 3 7 8, and I said, if they are on the right plugs, and timed at tdc compression it should go, but you are right, if the rotor is at #1.
The plug wires are marked, they are in the right rotation and order, 1 5 4 2 6 3 7 8, and I said, if they are on the right plugs, and timed at tdc compression it should go, but you are right, if the rotor is at #1.
Okay, I see what you mean by numbers. I didn't notice those before. Not sure but looks like the number 7 on the coil wire which seems weird. Appears the wires (based on the numbers) at least run to the correct side of the engine.
It doesn't really matter where the vacuum canister points but the problem you'll run into is that if it's not correct, you'll have to adjust your distributor and the plug wires won't be long enough. Older vehicles this is no problem, you just move your plug wires over. On newer vehicles the computer uses the distributor to trigger the injectors so it must go in correctly
Not sure but looks like the number 7 on the coil wire which seems weird. Appears the wires (based on the numbers) at least run to the correct side of the engine.
