Distributor trouble?
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
Distributor trouble?
Ok, my engine is broken in. I can't run it more than 5-10 minutes without it getting hot and will have to work through that issue.
I have been following the timing sticky by Barry and I set my dwell right on 30 at idle. But when I rev it up it goes up to 36 or more. I am not really revving it very high either. According to the stick if this happens then my distributor main shaft has too much end play and needs to be repaired. Is this correct and do I seem to have this problem based on the changes in the dwell? Reason I say this is because the distributor was rebuilt by Lars and just now put into service.
I have been following the timing sticky by Barry and I set my dwell right on 30 at idle. But when I rev it up it goes up to 36 or more. I am not really revving it very high either. According to the stick if this happens then my distributor main shaft has too much end play and needs to be repaired. Is this correct and do I seem to have this problem based on the changes in the dwell? Reason I say this is because the distributor was rebuilt by Lars and just now put into service.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Dwell is the length of time the points stay open. 30* is the center of the recommended range. They only way that will change is if the cam in the distributor is worn. And the number can't go up. If it's set at 30*, and the cam wears, (or the points wear) the dwell becomes less as the points close up.
You can "feel" your distributor and get a rough idea of any wear. Pull the cap, grab the rotor and pull straight up. The shaft should pull up a tiny amount- just enough to feel it. It's only .005, very small amount so if there's a big amount then you have a problem there. remember the distributor shaft will turn as it moves up too, so don't confuse the turn with the amount it moves up and down. If you're really worried, pull the distributor and measure the clearance between the top of the gear and the shim.
For that reason, I'm thinking you may have dwell and timing mixed up. At idle, your timing should be somewhere between 4 and 12*, with the advance coming in per the sticky. If you have the initial advance set at 30* that will be the cause of your heating problem. You need to check your initial timing and then add RPM to get to 36* @ 3000 RPM.
You can "feel" your distributor and get a rough idea of any wear. Pull the cap, grab the rotor and pull straight up. The shaft should pull up a tiny amount- just enough to feel it. It's only .005, very small amount so if there's a big amount then you have a problem there. remember the distributor shaft will turn as it moves up too, so don't confuse the turn with the amount it moves up and down. If you're really worried, pull the distributor and measure the clearance between the top of the gear and the shim.
For that reason, I'm thinking you may have dwell and timing mixed up. At idle, your timing should be somewhere between 4 and 12*, with the advance coming in per the sticky. If you have the initial advance set at 30* that will be the cause of your heating problem. You need to check your initial timing and then add RPM to get to 36* @ 3000 RPM.
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
Dwell is the length of time the points stay open. 30* is the center of the recommended range. They only way that will change is if the cam in the distributor is worn. And the number can't go up. If it's set at 30*, and the cam wears, (or the points wear) the dwell becomes less as the points close up.
You can "feel" your distributor and get a rough idea of any wear. Pull the cap, grab the rotor and pull straight up. The shaft should pull up a tiny amount- just enough to feel it. It's only .005, very small amount so if there's a big amount then you have a problem there. remember the distributor shaft will turn as it moves up too, so don't confuse the turn with the amount it moves up and down. If you're really worried, pull the distributor and measure the clearance between the top of the gear and the shim.
For that reason, I'm thinking you may have dwell and timing mixed up. At idle, your timing should be somewhere between 4 and 12*, with the advance coming in per the sticky. If you have the initial advance set at 30* that will be the cause of your heating problem. You need to check your initial timing and then add RPM to get to 36* @ 3000 RPM.
You can "feel" your distributor and get a rough idea of any wear. Pull the cap, grab the rotor and pull straight up. The shaft should pull up a tiny amount- just enough to feel it. It's only .005, very small amount so if there's a big amount then you have a problem there. remember the distributor shaft will turn as it moves up too, so don't confuse the turn with the amount it moves up and down. If you're really worried, pull the distributor and measure the clearance between the top of the gear and the shim.
For that reason, I'm thinking you may have dwell and timing mixed up. At idle, your timing should be somewhere between 4 and 12*, with the advance coming in per the sticky. If you have the initial advance set at 30* that will be the cause of your heating problem. You need to check your initial timing and then add RPM to get to 36* @ 3000 RPM.
I can recheck tomorrow and I will check the play as you said.
I will also do the total timing. But if my distibutor is bad the timing will have to be redone. But so what, I need the experience and I would love to solve the heating problem that easily. BTW - Since break in, with vaccum advance line plugged, I set my initial timing to 4 per the book.
Last edited by AWilson; Sep 13, 2009 at 03:09 AM.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Check the gap between the bottom of the distributor and the gear, you should have less than .060 movement up and down. If more than that than you need to insert a shim.
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
Ok, I measured the amount that the distributor pulls up. I got .016 end play. 16 thousandths. That should be well within specs., shouldn't it? So what could be causing the dwell to move 6-7 degress higher between idle and higher RPM"S?
Last edited by AWilson; Sep 13, 2009 at 10:26 AM.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
The easiest and fastest way to know if you have an upper distributor bushing failure is to go to the dwell.
Awilson, you need to pull the distributor on this car and check the bushings as well as the condition of the main shaft.
Willcox
Awilson, you need to pull the distributor on this car and check the bushings as well as the condition of the main shaft.
Willcox
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
I just learned about spark scatter too. Maybe I have this. At high RPM, 3000 the timing mark jumps every couple of seconds then goes back. I thought this was normal.
Last edited by AWilson; Sep 13, 2009 at 11:49 AM.
Intermediate
Joined: Aug 2009
Posts: 28
Likes: 0
if youre setting dwell you obviously have a points style ign. If youre hving issues w/ the dwell jumping around you most likely have a worn dist. shaft. now the easiest,best, and cheepest way to fix it would be to convet the distributer points with "Pertronics" style ign. You dont have to pull the stem or anything,just install according to directions in the box. you can get these units @ carquest or napa. They are much less persnickety than points especially if dist play is an issue. Plus you wont even have to swap youre cap or rotor, it all stays stock
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Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
AWilson,
I like to set the new points to 28 and used to 30. They can move open a little bit but nothing like you describe.
Replacement of the points kit with an HEI replacement would not be an option at this point. With the variance you have the upper bushing is either worn out or the point plate is worn out. One of the two can cause this problem but 99 percent of the time it is the upper bushing.
I don't know what type of H/P you have in your engine, but point bouce is not going to play a roll at 3000 RPM's with a good distributor. If you are running a H/P engine after a distributor re-build, I then would consider the HEI conversion kiits. If you are really pushing the h/p then do as I did on my 72 and go to the MSD or Excel Distributors. MSD makes a great tach drive distributor but you'll need the coil and the 6AL ignition box to run it.
IMHO,
Willcox
I like to set the new points to 28 and used to 30. They can move open a little bit but nothing like you describe.
Replacement of the points kit with an HEI replacement would not be an option at this point. With the variance you have the upper bushing is either worn out or the point plate is worn out. One of the two can cause this problem but 99 percent of the time it is the upper bushing.
I don't know what type of H/P you have in your engine, but point bouce is not going to play a roll at 3000 RPM's with a good distributor. If you are running a H/P engine after a distributor re-build, I then would consider the HEI conversion kiits. If you are really pushing the h/p then do as I did on my 72 and go to the MSD or Excel Distributors. MSD makes a great tach drive distributor but you'll need the coil and the 6AL ignition box to run it.
IMHO,
Willcox
Le Mans Master
Joined: Nov 2008
Posts: 5,691
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From: columbus oh
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
New symptom
Ok, It appears that I did not have enough vacuum to allow me to be aware of all problems. Now that the vacuum is coming direct from the manifold and the distributor can is working I have a new symptom.
It is intermittent but I would say about 2/3 of the time the distributor is making a very fast clickety click sound. Not high pitched. When this happens the timing retards a good 4-6 degrees. The 1/3 of the time it is not doing it the timing snaps back. It only happens under about 950 rpm.
It is intermittent but I would say about 2/3 of the time the distributor is making a very fast clickety click sound. Not high pitched. When this happens the timing retards a good 4-6 degrees. The 1/3 of the time it is not doing it the timing snaps back. It only happens under about 950 rpm.
Last edited by AWilson; Sep 20, 2009 at 07:24 PM.
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
Melting Slicks
Joined: Jul 2004
Posts: 2,862
Likes: 195
From: Maryland
If you stick to the stock distributor then get it blueprinted to the specs for your engine. Have it taken apart, inspected for worn parts, lubed and the ignition map correctly curved to your engines spec. Correct the gear end play to .005-.010. Use HD points(BW112Hp, Accel 8104 kit) , a non emissions cap and rotor and the correct VAC for your engines vacuum characteristics. If you need a contact to do this work I can refer one to you.
The noise in your distributor is probably interference with the rotor tang & cap contacts. Check for deep marks on the cap contacts
The noise in your distributor is probably interference with the rotor tang & cap contacts. Check for deep marks on the cap contacts
Last edited by Donald #31176; Sep 20, 2009 at 10:40 AM.
