1979 W72 Spark Plug Wiring Help Needed - Second Generation Pontiac Firebird (1970 - 1981) - Firebird Nation

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1979 W72 Spark Plug Wiring Help Needed


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11 replies to this topic

#1 Brock219

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  • Model: Trans Am SE
  • Engine: 400
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Posted A week ago

Doing reassembly after an engine compartment restoration of my 1979 W72 Y84 SE 4-Speed car. All new front and a/c wiring harnesses. Also, powder coated all the metal components - photo attached.

Now doing the reassembly. Somehow the spark plug wires at the distributor became disconnected - likely, one of my helpers. Does anyone have the correct spark plug wire assignments on the distributor cap? Have seen several diagrams on-line, but not sure any differences for the W72 engine, and the HEI. Kindly advise. Thanks so much!

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#2 myk74

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Posted A week ago

Was the distributor removed? I would go with this chart.

 

http://www.gtsparkpl...er-pontiac.html

 

If the dizzy wasn't removed and that chart doesn't work, move #1 one spot counter clockwise and all the others accordingly



#3 Brock219

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Posted A week ago

Was the distributor removed? I would go with this chart.
 
http://www.gtsparkpl...er-pontiac.html
 
If the dizzy wasn't removed and that chart doesn't work, move #1 one spot counter clockwise and all the others accordingly


Distributor was not removed - only cap for inspection. Question: why move wires one spot counter-clock wise? Kindly advise.

#4 myk74

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Posted A week ago

When I googled it I found the number1 in both spots.. But at this point, it needs to be put on where it was which could be anywhere unless you plan on restabbing the distributor. I would try the previous suggestions or find Top dead center and see where the rotor cap points. It should be pointing to number1



#5 b_hill_86

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Posted A week ago

Agree, if you dont remember what wires were where, you need to rotate the engine over so #1 cylinder is at top dead center on the compression stroke (not the exhaust stroke) and where the rotor points will be #1. From there, work counterclockwise in this order. 1-8-4-3-6-5-7-2. The left bank of cylinders is 1-3-5-7 from front to back and the right bank is 2-4-6-8 front to back.

#6 Brock219

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Posted A week ago

Thanks so much, guys. Have not ever attempted trying to find TDC on a modern V-8, but principles the same as any engine. Last one I did it on was my grandfathers 1930 Willys Overland Whippet, which he bought new and is still in the family - things much easier on a straight 6! Pic below when the car was 4 years old, my grandfather with his Dad out in their orchard in Ludington, Mi.

Will give it a shot tomorrow evening and report back. Thanks so much for everyones help!

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#7 b_hill_86

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Posted A week ago

That picture of the Willys is awesome! I actually grew up in Toledo which was the home of the Willys plant (became Jeep). I had several family members including a great grandmother I think who worked there back when it was still Willys. My maternal grandfather, aunt and father all worked at jeep (at that plant). My dad retired from there in 04 I think and they shut it down a few years later after a new plant had been built.

The plant is gone now but there is still one huge brick smokestack standing that says OVERLAND vertically.

Sorry to get off subject. Jeeps are what got me into cars as a kid so the Willys history always interested me too.

#8 Brock219

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Posted A week ago

Great connections! I saw the plant in operation and stopped by with the car on a trailer in route down here to NC - thought it deserved to visit its birthplace. Have a pic somewhere with the Overland smokestack in the background. Car has indeed been around - below a similar angle pic from a few years ago, when had it out for an event in CA. It is unrestored, save some paint freshening and runs fabulous, though certainly no match for the W72! Whatever the era, always great to have some history you can drive!

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#9 b_hill_86

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Posted A week ago

Yea thats really cool. Thanks for sharing those.

#10 Brock219

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Posted A week ago

Agree, if you dont remember what wires were where, you need to rotate the engine over so #1 cylinder is at top dead center on the compression stroke (not the exhaust stroke) and where the rotor points will be #1. From there, work counterclockwise in this order. 1-8-4-3-6-5-7-2. The left bank of cylinders is 1-3-5-7 from front to back and the right bank is 2-4-6-8 front to back.


That did it - quarter turn and the W72 roared right back to life! Thanks again, Myk74 and b-hill-86!

#11 myk74

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Posted A week ago

Glad you got it going. Where did #1 end up being?



#12 Brock219

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Posted A week ago

Glad you got it going. Where did #1 end up being?


Without finding TDC, would have never guessed - was one space clockwise from the diagram you forwarded. Likely from when the previous owner re-built the top end of the W72. With new plugs, wires and all new engine, front end and ac harnesses, plus all the vacuum lines hooked up, and all the correct ac brackets, runs better than ever!

More engine detailing to do in a future project - previous owner painted it the wrong color - plus cleaning and power coating the subframe and front suspension. All that for another winter, as the above and cleaning and powder coating the inner fenders, core support (installed new bushings), bumper and all the front brackets, plus restoring the evaporator box, new condenser, ac hoses and getting radiator cleaned and painted, and painting the firewall was enough.

Will be posting some pics of the vacuum lines plus the ac brackets, as would be good to have an easy reference for the forum users.

Thanks again for all your kind assistance!




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