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Basics firing order question |
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roadventure
AMC Nut Joined: May/23/2020 Location: Delaware Status: Offline Points: 278 |
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Posted: Jan/28/2023 at 3:13pm |
I changed the spark plugs in my 69 AMX (390 4V) yesterday and was careful to do one at a time and make sure that each cable went to the plug that was removed and replaced. The car runs great and this is the first engine maintenance thing I have done (except for changing oil/filter) since I got the car in July 2021. My question is this... I checked the Technical Service Manual (TSM) and, on page 4-27 it has a graphic showing the the engine firing order and the related distributor firing order. It's different than the reality on my car shown below. Using the screws as reference my distributor seems to be rotated 45 degrees CCW from the OEM orientation. Some other information: This distributor DOES have an electronic module inside (www.breakerless.com) replacing the OEM points but I didn't read anything in the instructions regarding a rotation that would require the distributor cap to be rotated as it is. Can someone educate me as to why my distributor is installed correctly? (remember, it does run great!) Thanks, Dave |
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ramblinrev
Moderator Group Joined: Dec/28/2008 Location: Wisconsin Status: Offline Points: 11470 |
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With a non-stock distributor, if you want to answer your questions, you need to find Top Dead Center on cylinder 1, and then take the distributor cap off, and find what 'tower' the rotor is lined up with. I don't think you can be 45 degrees off and run right, but you could be 180 degrees off.
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74 Hornet Hatchback X twins (since 1977)
62 American Convertible (still worth the $50 I spent in 1973!) AMCRC #513, AMO #384 70 AMX 360 4-speed (since 1981) |
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5454 |
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Your firing order on your cap is correct. If all you are worried about is the orientation of the distributor, turn the distributor body to where you want it, move the drive gear so the rotor points at the #1 tower, replace all the wires, re-time the engine and you are good.
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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The distributor can be installed any direction as long as the oil pump drive is aligned and the wires are located to match. Likely at some time in the past someone dropped distributor in wherever it took to engage the oil pump, then found tdc and simply installed the wires per the firing order.
If it runs fine and the timing is right leave it. If you want to align it as per original you can, but the wires have to be relocated, then pull the distributor and find the tooth that allows TDC to align, then stick a long screwdriver down and re-aline the oil pump to match. Then the engine has to be re-timed. It's a pain in the behind! Edit - treed by 6pak
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roadventure
AMC Nut Joined: May/23/2020 Location: Delaware Status: Offline Points: 278 |
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Thanks to everyone who answered. The explanations make sense. As I stated, it does run well and I have no compelling reason to make the changes made so the distributor aligns per the TSM. I appreciate you all sharing your knowledge!
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