Matt Harwood

Diagnostic Challenge!

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I think I can see a track running out to the bottom of the cap.

Then at the end of that track there is evidence of arcing where the cap sits on the distributor.

I might also see a crack between near that inside post and the one to its right in the picture.

I can only see this on the dirty (I assume before) picture.

I say cap.

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Benefits of AACA Membership.

Matt,

 

I don't know how long it will take to get the replacement cap, but apparently the difference between the tripower cap and regular Delco window caps is not the diameter, it's the location of the point adjustment window. The tripower cap has the window right next to one of the mounting screws, whereas the normal cap has it more centered between the two. Apparently you can use the conventional cap on a tripower car, you just can't access the points through the window. If the correct replacement takes a while to arrive, you might try a new conventional cap temporarily to see if the misfire goes away.

 

Top photo shows clocking of the window on a tripower cap, lower photo on a conventional cap. The clocking difference is about one tower.

 

s-l1600.jpg

 

s-l1600.jpg

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So I’m sitting here thinkn anybody knows the caps are all the same. I love it when I learn something new. Seems that happens on this forum a lot. Thanks!  Where does a body find such an unusual part? 

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15 minutes ago, Studeous said:

So I’m sitting here thinkn anybody knows the caps are all the same. I love it when I learn something new. Seems that happens on this forum a lot. Thanks!  Where does a body find such an unusual part? 

 

I had exactly the same thought, until I did some research. If the different window location surprises you, this one will blow your mind (hint, that's for a Corvette dual point distributor). 😉

 

B4003-060-1-Web.jpg

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Remember those, since you mentioned it. Thanks!  In high school I craved a brown delco remy distributer cap for my 55 chevy. Never did get one. Dont remember if too expensive or too hard to find........or I just didn’t know how to find one. 

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When I saw the carbon tracking on the cap, I just did a search for a "1959 Cadillac distributor cap" and found several for $35. Nice! But then I saw one that was about five times that much. That's odd, what's the difference? I did some additional reading and found several posts on the CLC message forum that said the Tri-Power distributors were smaller to clear the rear carb. They also mentioned the different location of the points window. With that knowledge, I checked with several vendors specializing in these cars and sure enough, all of them had reproduction Cadillac distributor caps whose fitment said "WILL NOT FIT 1958-1960 TRI-POWER." In fact, it appears that all Cadillac distributor caps from 1956-1974 are identical EXCEPT the Tri-Power caps.

 

Now whether the diameter is different or it's just the window, I don't rightly know, but I didn't want to make my #1 most common mistake and buy the wrong one even if it was a lot cheaper. We'll definitely find out when the presumably correct one arrives this week. I'm in no real hurry to get this car running, we have plenty of other cars to service, so whenever it shows up we'll give it a try. But knowing it may just be the points window, I may compare it to or maybe even try the cap from the 1963 Cadillac I have parked a few bays over...

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Does the tripower cap require its own unique rotor due to the difference in the cap from the others?  This is the type of question that pops into my mind at 2am when I should be sleeping.

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1 hour ago, TerryB said:

Does the tripower cap require its own unique rotor due to the difference in the cap from the others?  This is the type of question that pops into my mind at 2am when I should be sleeping.

It would if it were actually smaller in diameter, not if the difference is just location of the window.

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1 hour ago, joe_padavano said:

It would if it were actually smaller in diameter, not if the difference is just location of the window.

Yes, that is why it came to me, if the cap difference is diameter then the rotor would have to be smaller too and be different from the non tripower cap.  I watch reruns of Columbo on Sunday nights and often have to ask “just one more question” as a result of that.

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On 6/26/2020 at 8:56 AM, joe_padavano said:

A 1980s Subaru still had points?

 

Memory not as good....

 

1979 Subaru.

 

Interesting, Tercel kept points until 1982.

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13 minutes ago, Frank DuVal said:

 

Memory not as good....

 

1979 Subaru.

 

Interesting, Tercel kept points until 1982.

 

I'm actually surprised that a 1979 Sube had points. The whole reason why automakers went to electronic ignition systems in the early 1970s was to comply with EPA requirements that the car meet emissions standards after 50,000 miles without a tuneup. I'm guessing that any point-style distributor that met that requirement must have been using the points as a low-current switch to trigger a CDI box or something like that so that even pitted points would still fire it.

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I think the 1980s Triumph TR8 with the aluminum V8 based on a 1960s Buick design had points too.  I was looking at buying one back then and the points distributor was a surprise to see.

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4 hours ago, TerryB said:

I think the 1980s Triumph TR8 with the aluminum V8 based on a 1960s Buick design had points too.  I was looking at buying one back then and the points distributor was a surprise to see.

 

Sorry, no. The US-spec TR8s came with electronic distributors.

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There was nothing unusual about points in imported cars in the late 70s. More unusual in 80-82 but there were still some around.

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7 hours ago, Bloo said:

There was nothing unusual about points in imported cars in the late 70s. More unusual in 80-82 but there were still some around.

 

I know that in the 1970s the EPA exempted some low-volume manufacturers from complying with all the emissions requirements. I don't know if that applied to the 50K mile without a tuneup requirement or not. I'm still wondering how points would go 50K miles without servicing. That's also why automakers went to high voltage coils and expensive spark plugs.

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OK, new distributor cap arrived and it was identical to the old one so it fit perfectly. Actually, it's better than the old one, with brass terminals instead of aluminum.


Unfortunately, #2 cylinder is still dead.


Now what? I'm out of ideas.

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How about a dynamic issue like an exhaust valve hanging when running but not when cranking for a compression test?  Put a vacuum gauge on it and read your problem by how the needle reacts.

 

 

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Can you verify you have spark when engine is running?  Can you see the spark generated?  Is it weak or intermittent?  

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Clamp an inductive timing light on the #2 spark plug wire and make sure the plug is firing in the cylinder.

 

Paul

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Might I suggest a shiny new plug for #2. And a substitute wire for same. Perchance the plugs and or wires got jumbled when swapping? You know, “in all the excitement, I lost count” kind of deal. Good luck cause you covered about anything else. 

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49 minutes ago, Studeous said:

Might I suggest a shiny new plug for #2. And a substitute wire for same. Perchance the plugs and or wires got jumbled when swapping? You know, “in all the excitement, I lost count” kind of deal. Good luck cause you covered about anything else. 

 

Go back and read post #1

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Posted (edited)

It is time to have a good look at the closest barrel of the closest carburetor.

 

Does this setup have idle jets on all carbs or just the center? Is it progressive linkage?

 

It is truly amazing how small a vacuum leak can be and still kill a cylinder, particularly if the leak is out on a runner.

Edited by Bloo (see edit history)

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3 hours ago, Matt Harwood said:

OK, new distributor cap arrived and it was identical to the old one so it fit perfectly. Actually, it's better than the old one, with brass terminals instead of aluminum.


Unfortunately, #2 cylinder is still dead.


Now what? I'm out of ideas.


 

Fix it.

 

Sorry..........all those terrible thing they say about me are true.

 

You need a KV tester. I realized I didn’t have one down south when we were talking about this thread, so I ordered one, It will be here next week. Compression, fuel, and spark......boom. If only it were that easy. Did you do a cylinder power balance test? I would still look for vacuum leaks.......most likely the cause. 

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Posted (edited)

Maybe a weak valve spring.  You could test it on the car by trying to push the valve open with a bar then noting the pressure difference between the two valves on the bad cylinder. Make sure that the piston is down and both valves are closed. You might have to take the pushrods out to do this. Pfitz's  timing light idea is good too.

Edited by misterc9 (see edit history)

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