1974 Distributor is Knocking
Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
. Lars has fed me a few tips for which I am thankful. We go back a long ways in this hobby.But here's the update for the day! I traced all the spark plugs wires and labelled them. See pic for normal (Lars' pic) and what some former owner thought was normal (my scribblings). Mr. #1 is near the firewall, not the typical location near the dwell access window. So........I was pointing the rotor tip in the wrong direction yesterday. That does not make things happen.
If you look closely at the pic you will see the 1-8-4-3-6-5-7-2 firing order is counter-clockwise: backwards. I can assure that this car was running last week, and nicely. Can a distributor sequence function backwards??
I will place the plug wires in the correct positions tomorrow, go through the #1 compression stroke and rotor exercise, and see what happens.
The mystery deepens. I will report back.
Last edited by Paul L; Aug 8, 2010 at 05:41 PM.
Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
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From: Ontario
Race Director
Joined: Jul 2001
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My brain is hurting trying to figure out how a reverse direction distributor could allow an engine to run or if such a thing exists.
Ow.
There is such a thing as a reverse direction SBC for marine use but I believe they still used a normal distributor. I would pull the cap and crank it over to see which way the rotor turns. Arrange the wires accordingly.
Ow.
There is such a thing as a reverse direction SBC for marine use but I believe they still used a normal distributor. I would pull the cap and crank it over to see which way the rotor turns. Arrange the wires accordingly.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Le Mans Master
Joined: Apr 2004
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From: Newark DE
Paul, I'd have to guess that if the wires were indexed incorrectly the whole time previous to this than whoever did that maybe found TDC based on a different cylinder to correlate with the strange indexing or something else screwed up like that... I don't know, my head hurts even trying to figure out what was done, how it was done, how it ran, etc before.
Whatever....
at this point I'd change things around to make it correct. Sure would make problem solving a lot easier not only now but also for any future work.
You already found TDC on the #1 cylinder so I'd trace back and mark every ignition wire to confirm what cylinder each wire is than connect them to the distributor cap with the normal correct indexing which is here:
I've found that when things get really confusing and messed up it ends up being easier to just start back at the very beginning and progressing from there (and you know me well enough to know I confuse easily so I start over a lot...
)
Whatever....
at this point I'd change things around to make it correct. Sure would make problem solving a lot easier not only now but also for any future work.
You already found TDC on the #1 cylinder so I'd trace back and mark every ignition wire to confirm what cylinder each wire is than connect them to the distributor cap with the normal correct indexing which is here:
I've found that when things get really confusing and messed up it ends up being easier to just start back at the very beginning and progressing from there (and you know me well enough to know I confuse easily so I start over a lot...
)
Race Director
Joined: Mar 2006
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From: Florida
The printed firing sequence on the picture is correct for a CW crank rotation chevy and the handwritten sequence is correct for a CCW crank rotation chevy.
You have an assembly (or at least the cap with installed wires) from a reverse rotation application.
In both applications the dist turns CW.
Make sure your vac advance is present and working properly, they are missing and not used on true marine distributers.
You have an assembly (or at least the cap with installed wires) from a reverse rotation application.
In both applications the dist turns CW.
Make sure your vac advance is present and working properly, they are missing and not used on true marine distributers.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
My brain is hurting trying to figure out how a reverse direction distributor could allow an engine to run or if such a thing exists.
Ow.
There is such a thing as a reverse direction SBC for marine use but I believe they still used a normal distributor. I would pull the cap and crank it over to see which way the rotor turns. Arrange the wires accordingly.
Ow.
There is such a thing as a reverse direction SBC for marine use but I believe they still used a normal distributor. I would pull the cap and crank it over to see which way the rotor turns. Arrange the wires accordingly.
What the heck is going on now , reverse rotation , what did I miss ?
EDIT- Paul , I agree with Barry , start over. To be honest if most guys would start from the beginning instead of trying to mark things and transfer things this probably wouldn't happen.
Find #1 TDC , drop your dist in with #1 in the position of the pic , install wires like the pic.
Stock wire lengths starting with the longest. 2,3,1,4,5,6,8,7........(2&3 are the same length,5&6 are the same length)
Last edited by ...Roger...; Aug 9, 2010 at 07:44 AM.
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Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
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From: Ontario
I fouled up yesterday!! But I gave it a go again this morning. The pic shows what I found. Basically all the wires are two terminals off. The #1 wire is in the #4 position, etc, etc. I'll continue to plug away at it.
Sometimes you just never know what has been done in the past!
*Edit* - I installed a new distributor cap with the wires in the correct positions. Basically started from scratch as some suggested above. I did the #1 cylinder pop/poof thing with the timing tab showing 4*BTDC. I dropped in the distributor with the rotor pointing to the now "correct" #1 position. The car started right up. I will now do the dwell and timing to complete the job.
I guess the lesson is that you should never assume that someone in the past has done things properly.
And I guess I now owe Roger a bottle of Tylenol....
Sometimes you just never know what has been done in the past!
*Edit* - I installed a new distributor cap with the wires in the correct positions. Basically started from scratch as some suggested above. I did the #1 cylinder pop/poof thing with the timing tab showing 4*BTDC. I dropped in the distributor with the rotor pointing to the now "correct" #1 position. The car started right up. I will now do the dwell and timing to complete the job.
I guess the lesson is that you should never assume that someone in the past has done things properly.
And I guess I now owe Roger a bottle of Tylenol....
Last edited by Paul L; Aug 9, 2010 at 01:44 PM.
Race Director
Joined: May 2006
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From: Dayton, Ohio
No Tylenol PM, please , that stuff makes me brain dead. 
Glad you got her gone. 
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Murpheys law!
Paul, did you mark reference points on the distributor housing and on the intake manifold to where the rotor was pointing before you removed it from the car? If you did you can drop it in the same position without having to go thru the whole procedure of finding TDC, etc
one of the times I had the distributor out of my '65 I marked the housing and rotor as seen here:
You can see the green mark and a black mark on the housing. The are also green and black marks on the rotor (but the rotor is turned to a different position in this pic so you can't see them).
I also marked a green mark on a piece of masking tape on the intake manifold showing the position of where the rotor was pointing for reference.
When it was time to drop the distributor back in I just aligned up my reference marks, moved the rotor slightly off the marks (because it will rotate a bit as you drop it back in because of the angle cut of the gears) and it went right in without having to refind TDC, etc
If you didn't mark the rotor position than yes, you will have to start from the beginning, find
TDC, than drop in in with the rotor pointing to #1 position on the cap.
one of the times I had the distributor out of my '65 I marked the housing and rotor as seen here:
You can see the green mark and a black mark on the housing. The are also green and black marks on the rotor (but the rotor is turned to a different position in this pic so you can't see them).
I also marked a green mark on a piece of masking tape on the intake manifold showing the position of where the rotor was pointing for reference.
When it was time to drop the distributor back in I just aligned up my reference marks, moved the rotor slightly off the marks (because it will rotate a bit as you drop it back in because of the angle cut of the gears) and it went right in without having to refind TDC, etc
If you didn't mark the rotor position than yes, you will have to start from the beginning, find
TDC, than drop in in with the rotor pointing to #1 position on the cap.
Once upon a time I was working on my dizzy.
Followed these instructions 100%, came into the house and poopsie said "Your not working on that greasy thing in my kitchen". Went back out and cleaned it.
Only realized I washed all the marks off when I went to reinstall it.
Glad you car is fixed.
Burning Brakes
Joined: Mar 2008
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From: Denver, CO
St. Jude Donor '08-'09-'10
sorry to chime back in so late. when i did it on mine, the pickup was a f150, so not chevy but still.. somehow i had the wires completely backwards and they were 4 off. so it was backwards and off..... and it ran! i dont know how. my point though was i hope you get them all back in correct orientation, which it appears you have. have fun driving!
