Repair Pontiac Mid-size 1974-1983 Repair Guide

Firing Orders

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Fig. Fig. 1 Pontiac built 151 cu. in. 4-cylinder engine Firing order: 1-3-4-2 Distributor rotation: Clockwise



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Fig. Fig. 2 Chevrolet built 250 cu. in. inline 6-cylinder engine Firing order: 1-5-3-6-2-4 Distributor rotation: Clockwise



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Fig. Fig. 3 Buick built 231 cu. in. (3.8L) and 252 cu. in. (4.2L) engines Firing order: 1-6-5-4-3-2 Distributor rotation: Clockwise



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Fig. Fig. 4 Oldsmobile built 260, 307, 350, 400, 455 cu. in. and Pontiac built 265, 301, 350, 400, 455 cu. in. V8 engines Firing order: 1-8-4-3-6-5-7-2 Distributor rotation: Counterclockwise



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Fig. Fig. 5 Buick built 350 cu. in. V8 engine Firing order: 1-8-4-3-6-5-7-2 Distributor rotation: Clockwise



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Fig. Fig. 6 Chevrolet built 305 and 350 cu. in. V8 engines Firing order: 1-8-4-3-6-5-7-2 Distributor rotation: Clockwise

To avoid confusion, remove and tag the wires one at a time.

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.

 
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