I need the plug wire order on the distribtutor. For a 72 ford truck, I beleve it has a 390 in it. my truck backfires every 10 seconds or so

Firing order can be obtained at any parts store, online or at a dealer. Misfiring can be a bad spark plug, a bad spark plug wire. Bad news is a bad value seat (most likely intake) or the fuel injector may be the issue.

Check this video for idle speed adjustment. Backfiring can be caused by incorrect mixing in the carburettor or bad timing settings.


Check this link for backfire issues:

. What would cause Ford 390 to backfire through carb Yahoo Answers

Setting Curb Idle Speed of Carburetor Video Holley Carb DVD

Sound like you got crossed plug wires.Your firing order is 1-5-4-2-6-3-7-8

255 cid (4.2L), 302 cid (5.0L), 360 cid (5.9L), 390 cid (6.5L), 460 cid (7.5L) V8 engines Firing order: 1-5-4-2-6-3-7-8 Distributor rotation: Counterclockwise




351 cid W & M (5.8L), 400 (6.6L) engines Firing order: 1-3-7-2-6-5-4-8 Distributor rotation: Counterclockwise

If you are sitting in the car or truck and you have a 290. The Drivers side is 5678 Passengers side is 1234 1 and 5 4 and 2 6 and 3 and 7 and 8

300 straight six 153624 distributor rotation clockwise, 232 v6 142536 distributor rotation counterclockwise.

255/302/360/390/460 15426378 distributor rotation counterclockwise,

351 & 400 W & M 13726548 distributor rotation counterclockwise.

the firing order for the ford 4.6 is 1-3-7-2-6-5-4-8

FIRING ORDERS NOTE: To avoid confusion, remove and tag the spark plug wires one at a time, for replacement. If a distributor is not keyed for installation with only one orientation, it could have been removed previously and rewired. The resultant wiring would hold the correct firing order, but could change the relative placement of the plug towers in relation to the engine. For this reason it is imperative that you label all wires before disconnecting any of them. Also, before removal, compare the current wiring with the accompanying illustrations. If the current wiring does not match, make notes in your book to reflect how your engine is wired. Fig. 1: 300 cid (4.9L) inline six-cylinder engines Firing order: 1-5-3-6-2-4 Distributor rotation: Clockwise
Fig. 2: 232 cid (3.8L) V6 engine Firing order: 1-4-2-5-3-6 Distributor rotation: Counterclockwise
Fig. 3: 255 cid (4.2L), 302 cid (5.0L), 360 cid (5.9L), 390 cid (6.5L), 460 cid (7.5L) V8 engines Firing order: 1-5-4-2-6-3-7-8 Distributor rotation: Counterclockwise
Fig. 4: 351 cid W & M (5.8L), 400 (6.6L) engines Firing order: 1-3-7-2-6-5-4-8 Distributor rotation: Counterclockwise
Fig. 5: 6.9L diesel engines Firing order: 1-2-7-3-4-5-6-8

make sure all wires are secure on the plugs. Make sure that if you bought the plugs aftermarket, that they are the suggested equipment from the Ford (http://www.car-stuff.com/carparts/fordtaurus20002000motorcraftmisp432154315.html Make sure the plugs (gap) were not damaged during installation. Check the firing order is correct. (1,4,2,5,3,6)

Do you have the "firing order" correct? In other words, is each spark plug wire going to the same cylinder it was on before you changed the plugs? If you have done nothing else but changed the plugs then this is the most likely problem.
If when you try to start the car it backfires through the exhaust or backfires through the intake. Then this " IS" the problem. Good luck.