1974 Distributor is Knocking
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Team Owner
Joined: Aug 1999
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From: Ontario
1974 Distributor is Knocking
I headed out this morning for a local event and stopped for gas. On start-up I noticed a knocking sound from the engine, upper end. It seemed to come on rather suddenly but perhaps it was there last weekend when I last drove and I did not notice it.
So I headed back to home port. It is an intermittent noise/knock that I have pretty much isolated to the distributor. In fact if I hold the distributor cap I can feel it. It is pronounced (on and off) at idle and with revving it seems to disappear or perhaps it is masked??
The car idles and runs well. No problems. The tach works. Very strange. I'm thinking distributor mainshaft bushings. But I would certainly appreciate opinions. I do have a rebuilt unit in the basement with Breakerless SE that I can install if need be but I will have to revisit Lars' tricks re #1, TDC, rotor to #1 etc.
Any one seen anything like this before?
So I headed back to home port. It is an intermittent noise/knock that I have pretty much isolated to the distributor. In fact if I hold the distributor cap I can feel it. It is pronounced (on and off) at idle and with revving it seems to disappear or perhaps it is masked??
The car idles and runs well. No problems. The tach works. Very strange. I'm thinking distributor mainshaft bushings. But I would certainly appreciate opinions. I do have a rebuilt unit in the basement with Breakerless SE that I can install if need be but I will have to revisit Lars' tricks re #1, TDC, rotor to #1 etc.
Any one seen anything like this before?
Last edited by Paul L; Aug 7, 2010 at 07:58 PM.
Thread Starter
Team Owner
Joined: Aug 1999
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From: Ontario
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
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From: Ontario
? Obviously someting went wrong to see that brass mush. I hope to get the reserve basement unit with Breakerless SE in tomorrow. I am tired. And will have to do the rotor# 1, TDC*, etc. trick. I'll get back to you tomorrow. Tonight I have just had enough with this car.
This week we had a severe rain and windstorm in the area (twice). A very pretty moutain ash came down and I just finished up with the tree removal company. It is gone and the stump reduced/chopped down to 8" below grade. So again I am tired. See you people tomorrow.
Last edited by Paul L; Aug 6, 2010 at 08:48 PM.
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)
There a some days we would just like to forget!
Looks like you not only lost a nice tree but it landed in your flower bed, bummer! Hope they didn't tare up all the Hosta's with the stump grinder.
Found out how expensive tree removal costs first hand.
About the dizzy here's a how to
http://www.tispecialty.com/articles/article6.htm
says thru 72 but it sure looks like up to 74.
Found out how expensive tree removal costs first hand.
About the dizzy here's a how to
http://www.tispecialty.com/articles/article6.htm
says thru 72 but it sure looks like up to 74.
Last edited by Peterbuilt; Aug 6, 2010 at 11:05 PM.
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Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
Looks like you not only lost a nice tree but it landed in your flower bed, bummer! Hope they didn't tare up all the Hosta's with the stump grinder.
Found out how expensive tree removal costs first hand.
About the dizzy here's a how to
http://www.tispecialty.com/articles/article6.htm
says thru 72 but it sure looks like up to 74.
Found out how expensive tree removal costs first hand.
About the dizzy here's a how to
http://www.tispecialty.com/articles/article6.htm
says thru 72 but it sure looks like up to 74.
I will probably try and install my basement rebuilt unit with Breakerless SE later today. I have Lars' "walking the distributor" paper. He tends to make things look easy but I do not have his experience and will probably run into problems. With compression on #1 he recommends a timing tab setting of 8 BTDC. That is my starting point. Hopefully all will go well.
The tree guys know their stuff. All debris has been chipped and hauled away. The stump is gone. We lost a bit of hosta but what the heck. It is also known as goutweed and spreads quickly or can be transplanted easily. IMO the cost was reasonable: $180.00 for the job and done within two days of the storm.
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If the engine vacuum at idle fluctuates and the vacuum canister is marginal in calibration, there can be a rattling sound from the dist I guess as the linkage hits the stops. Obviously not the case here though.
Thread Starter
Team Owner
Joined: Aug 1999
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From: Ontario
http://forums.corvetteforum.com/c1-a...post1574326672
Last edited by Paul L; Aug 7, 2010 at 12:26 PM.
Le Mans Master
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From: Newark DE
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.
Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
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.
No I did not do that. I did mark the #1 position on the latest distributor base as seen from an installed cap: just clockwise from the dwell window.
With the help of my Brother we did the #1 TDC thing and verified with valve cover off that both valves were closed. Then dropped the distributor in with rotor pointing to #1 position.
Unfortunately the car will not start. I am very perplexed as we seemed to follow the procedures. It just will not fire. Gas is fine (it floods) and pulling a plug to see spark was positive. All electrical hookups are fine. This is all very strange.
I even pulled the new Breakerless SE off in case it was defective and put in a new set of points and condensor. Still no go.
So I am burned out for the day and quite frankly have run out of ideas even for tomorrow. Very frustrating. Even with the bum distributor yesterday the car was running fairly well albeit with distributor noise and a failed tach gear.
Is it 180* out? According to procedures no. But that is a possibility. Anyone know a test to say yes or no? Have I missed something obvious?
Last edited by Paul L; Aug 7, 2010 at 05:51 PM.
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Team Owner
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From: Ontario
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From: Florida
Here is an very easy way using an old spark plug to make a tool.
Note that the balloon won't stay inflated, but it will tell you what you need to know and that is that you are on the compression stroke. Since you know that, then just continue turning the crank till the timing marks line up.
This shows an hei, but use the rotor location for a points cap.
Note that the balloon won't stay inflated, but it will tell you what you need to know and that is that you are on the compression stroke. Since you know that, then just continue turning the crank till the timing marks line up.
This shows an hei, but use the rotor location for a points cap.
Try this way.
Looking at the front of the engine from the front of the car the balancer turns clockwise. The distributer turns clockwise looking down at it.
Almost foolproof method:
Get an old sparkplug that fits the engine.
Knock the guts out of it with a punch and hammer.
Stretch a balloon over the sparkplug leaving the threads exposed. (Balloons from Dollar Store)
Hand tighten the balloon/sparkplug into the #1 hole.
Disconnect power to distributor or make sure ignition is off.
Slowly turn over engine in clockwise direction with a socket and ratchet on the harmonic balancer center bolt.
Balloon will fill with air when approaching #1 firing position. It won't stay full so you have to watch it closely.
The mark on the balancer will be at approx 6 o'clock, so forget about the ballon and continue turning the engine over.
Continue to turn engine until the mark on balancer reaches the 10° BTDC mark.
This is close to the initial timed firing position.
Install dist with the rotor pointing approximatedly at the #2 terminal on the cap. (Just before #1 on cap)
Push down slowly and you will feel the gears mesh and the rotor will move toward the #1 position.
If it is going to go past #1, then slowly pull up on the distributer until you feel the gears "unmesh". then turn the rotor more towards the #2 direction with slight pressure down until you feel you have moved over 1 more tooth.
Then push down as far as it will go again to see if it is close to lining up with #1 terminal.
If the distributer housing base where you clamp it tight has a gap between it and the intake manifold, then the oil shaft has not lined up.
If this is the case, then the rotor should be between the #1 and #2 terminals on the cap.
Then just push down lightly on the distributer housing (watch out for spinning rotor) while someone cranks the starter over, and it will drop in place and the timing will be correct to fire up.
It may sound a little confusing, but try it and it's pretty simple and is is the easiest way I have found.
To check it, do the balloon thing again with the distributor now being fully seated on the intake. Turn the distributer housing until the rotor leading edge meets the #1 cap terminal. If the housing is oriented properly as in the first pic then you will have ample room for the vacumn advance can to turn the distributer for timing. Now clamp the distributor fairly tight and use you timing lite to time engine to your specs.
Use one of the papers in a sticky at top.
Looking at the front of the engine from the front of the car the balancer turns clockwise. The distributer turns clockwise looking down at it.
Almost foolproof method:
Get an old sparkplug that fits the engine.
Knock the guts out of it with a punch and hammer.
Stretch a balloon over the sparkplug leaving the threads exposed. (Balloons from Dollar Store)
Hand tighten the balloon/sparkplug into the #1 hole.
Disconnect power to distributor or make sure ignition is off.
Slowly turn over engine in clockwise direction with a socket and ratchet on the harmonic balancer center bolt.
Balloon will fill with air when approaching #1 firing position. It won't stay full so you have to watch it closely.
The mark on the balancer will be at approx 6 o'clock, so forget about the ballon and continue turning the engine over.
Continue to turn engine until the mark on balancer reaches the 10° BTDC mark.
This is close to the initial timed firing position.
Install dist with the rotor pointing approximatedly at the #2 terminal on the cap. (Just before #1 on cap)
Push down slowly and you will feel the gears mesh and the rotor will move toward the #1 position.
If it is going to go past #1, then slowly pull up on the distributer until you feel the gears "unmesh". then turn the rotor more towards the #2 direction with slight pressure down until you feel you have moved over 1 more tooth.
Then push down as far as it will go again to see if it is close to lining up with #1 terminal.
If the distributer housing base where you clamp it tight has a gap between it and the intake manifold, then the oil shaft has not lined up.
If this is the case, then the rotor should be between the #1 and #2 terminals on the cap.
Then just push down lightly on the distributer housing (watch out for spinning rotor) while someone cranks the starter over, and it will drop in place and the timing will be correct to fire up.
It may sound a little confusing, but try it and it's pretty simple and is is the easiest way I have found.
To check it, do the balloon thing again with the distributor now being fully seated on the intake. Turn the distributer housing until the rotor leading edge meets the #1 cap terminal. If the housing is oriented properly as in the first pic then you will have ample room for the vacumn advance can to turn the distributer for timing. Now clamp the distributor fairly tight and use you timing lite to time engine to your specs.
Use one of the papers in a sticky at top.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Paul,make sure when your looking at the valves on #1 being closed , that #3 intake and #5 exhaust are also open.
This will ensure you are on #1 firing stroke and NOT on #6 firing stroke.
This will ensure you are on #1 firing stroke and NOT on #6 firing stroke.
Last edited by ...Roger...; Aug 7, 2010 at 07:31 PM.
