Dual point distributor ID question

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mvh

mvh

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I have a Prestolite distributor labeled "273-4 1967", but the part number on the tag is not correct for 67 according to the FSM and another reference I have. I was wondering if anyone could identify the application? I am wondering if it's for a 65-66 (I don't have any references for 66 and earlier) as it doesn't match up with any 340 numbers either. Or maybe it's a factory replacement?

2642461
IBS-4013AS 183

By the book, 67 273-4 CAP would be 2642358 IBS-4013B; w/o CAP would be 2642242 IBS-4013A (this is what is on my car, which is correct since it's from Oregon).

IMG_5646.jpeg
 
Back in the day we had actual parts books. Good luck

MyMopar has scans of some years of Chrysler OEM parts books, but those would be OEM no's and not Prestolite I believe. Might be worth a look
 
Prestolite was OEM for this application in this time frame (also for 340s and Hemis). Haven't searched for parts books yet.
 
mvh said:
I have a Prestolite distributor labeled "273-4 1967", but the part number on the tag is not correct for 67 according to the FSM and another reference I have. I was wondering if anyone could identify the application? I am wondering if it's for a 65-66 (I don't have any references for 66 and earlier) as it doesn't match up with any 340 numbers either. Or maybe it's a factory replacement?

2642461
IBS-4013AS 183

By the book, 67 273-4 CAP would be 2642358 IBS-4013B; w/o CAP would be 2642242 IBS-4013A (this is what is on my car, which is correct since it's from Oregon).

View attachment 1716069409
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2642461 is for a 66 or 67 273-4 barrel without CAP (Clean air Package)
 
Yes, I just checked the 1966 FSM, and the specs are identical between it and the 2642242 which is what is listed for 1967 (and is in my 67 FB). But the # is listed for 1966.

So, why the different part number, is my question? Whatever...
 
mvh said:
Yes, I just checked the 1966 FSM, and the specs are identical between it and the 2642242 which is what is listed for 1967 (and is in my 67 FB). But the # is listed for 1966.

So, why the different part number, is my question? Whatever...
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My book shows the same part number for 66 and 67.
2642405 is with CAP Did you read my post #5?
 
Yes, I did. What book are you referring to? I was looking at the Plymouth factory service manuals for 1966 and 1967. Seems there is a contradiction. I suspect the 1967 FSM is actually correct, because it lists the part number that is actually installed on my very original car (2nd owner). But it's just a quibble about the number tag, since the actual unit is exactly the same in all specs.
 
mvh said:
Yes, I did. What book are you referring to? I was looking at the Plymouth factory service manuals for 1966 and 1967. Seems there is a contradiction. I suspect the 1967 FSM is actually correct, because it lists the part number that is actually installed on my very original car (2nd owner). But it's just a quibble about the number tag, since the actual unit is exactly the same in all specs.
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I have a few Galen Govier parts books.
 
Well, I can't say he is "wrong", since it's the same part. But a "correct" tag for a 67 w/o CAP should be 2642242 based on actual evidence. He was probably fooled by a parts interchange manual showing 66 and 67 as identical, which is true, but for some reason Mopar changed the number on the tag, and documented it in the FSM.

Oddly, despite every other ignition spec being identical for those two years, Mopar also changed the spark plug from Champion N9Y to N10Y... who knows why?
 
mvh said:
Well, I can't say he is "wrong", since it's the same part. But a "correct" tag for a 67 w/o CAP should be 2642242 based on actual evidence. He was probably fooled by a parts interchange manual showing 66 and 67 as identical, which is true, but for some reason Mopar changed the number on the tag, and documented it in the FSM.

Oddly, despite every other ignition spec being identical for those two years, Mopar also changed the spark plug from Champion N9Y to N10Y... who knows why?
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9's were too cold. The manuals are written and printed a half year ahead of time and any changes don't come until the next year. The 4 barrel engine was only produced in 65,6, and 7. There was no CAP in 65 so they need a little different calibration in 66 and 7.
 
OK, that makes sense.

I have been studying up on the ignition specs because I'm trying to figure out why my car is pinging so bad. Apparently it was pulling 53º total advance, which is nuts. All in, by the book, should be 32.5º (I'm assuming the 10º at 1800 is the maximum centrifugal advance), but it was pulling 38º on the centrifugal alone. So I was contemplating swapping in this other distributor. It should be identical, in theory, but maybe the springs are in better shape. I also have a CAP distributor, but it dials in more centrifugal advance, faster, which wouldn't seem to help.
 
mvh said:
Prestolite was OEM for this application in this time frame (also for 340s and Hemis). Haven't searched for parts books yet.
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I know full well---what I was referring to is a Prestolite number as opposed to an OEM part number
 
mvh said:
OK, that makes sense.

I have been studying up on the ignition specs because I'm trying to figure out why my car is pinging so bad. Apparently it was pulling 53º total advance, which is nuts. All in, by the book, should be 32.5º (I'm assuming the 10º at 1800 is the maximum centrifugal advance), but it was pulling 38º on the centrifugal alone. So I was contemplating swapping in this other distributor. It should be identical, in theory, but maybe the springs are in better shape. I also have a CAP distributor, but it dials in more centrifugal advance, faster, which wouldn't seem to help.
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53 is not unheard of if you are talking complete full advance with both vacuum and centrifugal AT THE CRANK. Don't forget, "the book" specs for dist advance is DISTRIBUTOR degrees, which must be doubled at the crank.
 
Take this example, 67 273 4bbl no clean air

Initial timing is 10BTC, plus mechanical is max of 20 + vacuum is 23 max, so that is 53 degrees total

273.jpg
 
67Dart273 said:
53 is not unheard of if you are talking complete full advance with both vacuum and centrifugal AT THE CRANK. Don't forget, "the book" specs for dist advance is DISTRIBUTOR degrees, which must be doubled at the crank.
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Doh! That didn't occur to me, because I have no way to directly measure distributor timing. That example is exactly what I have, interestingly.
 
mvh said:
Doh! That didn't occur to me, because I have no way to directly measure distributor timing. Still, I've heard all-in timing should not exceed 40º, typically.
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No that is full throttle balls to the wall. At that point, the vacuum is out because with the carb wide open, there is no vacuum, so that is initial + mechanical. Also that can vary some but 40 (actually less nowadays) is a good figure

I was astounded to learn that G3 hemis want WAY WAY less, more like low 20's at the crank
 
Ah, got it. Where it seemed to be pinging was half throttle, right off cruise. Which didn't seem right, because as soon as you depress the accelerator, the vacuum drops right off (per the gauge).
 
I don't know what all can cause that. Certainly carb/ vacuum advance mismatch, engine using some oil (valve guides), too lean or too hot, not sure what else. "Back then" for awhile I had a 71 high compression 340 in an old Landcruiser, and typically ran either Holley spread bore or QJ 4 bbl. Seems to me the QJ always had that problem, heavy "lug" load, part throttle rattle. On the other hand I used to run "plenty" of timing, and likely too much LOL
 
The carb was lean at cruise — fixed. Timing was a tad advanced (14 at idle). Trying a different set of plugs now.
 
mvh said:
Ah, got it. Where it seemed to be pinging was half throttle, right off cruise. Which didn't seem right, because as soon as you depress the accelerator, the vacuum drops right off (per the gauge).
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Pull the hose off the distributor and plug it and go for a drive. If the ping goes away at least you know the vacuum advance is causing it. Where is your initial timing set?
 
It's at a shop because my new HOA won't let me work on it in my driveway. They have been driving it w/o the vac advance, and they set the timing to stock (10ºB). But they just called to say when they did that, it made the idle slightly rougher, and they could hear the heat riser flapping, and now they're wondering if we both were mistaking that for pinging. So they are wiring it open as a test.

The motor is just far enough away from stock that's it's a little bit of a guessing game. Rebuilt years ago at .030 over, w/ TRW hypereutetic pistons, Crower hydraulic cam with a smidge more lift, plus a recent set of used heads with new valves and a mild port, 2-1/2" dual exhaust.
 
mvh said:
It's at a shop because my new HOA won't let me work on it in my driveway. They have been driving it w/o the vac advance, and they set the timing to stock (10ºB). But they just called to say when they did that, it made the idle slightly rougher, and they could hear the heat riser flapping, and now they're wondering if we both were mistaking that for pinging. So they are wiring it open as a test.

The motor is just far enough away from stock that's it's a little bit of a guessing game. Rebuilt years ago at .030 over, w/ TRW hypereutetic pistons, Crower hydraulic cam with a smidge more lift, plus a recent set of used heads with new valves and a mild port, 2-1/2" dual exhaust.
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That's too bad. You really don't know what you have for sure it seems. I would leave the initial around 10° to start. Some people continue to advance the initial until it kicks back against the starter and then retard it a couple degrees. No more than 32° or so at say 3000 rpm with the vacuum advanced disabled. Those original distributors don't have adjustable vacuum canisters unless you take the end apart and shim the spring. You can get into the advance mechanism's with lighter springs for quicker advance (which may have happened to yours) and the advance plates can be changed or the slots modified for more or less centrifugal advance. It's a science for sure and too much, too fast, or at the wrong time can cause detonation. A noisy heat riser is another thing. :BangHead: :BangHead:
 
I'm pretty sure the distributor hasn't been messed with other than high mileage. Oh, except the vacuum advance was replaced... possibly with a different washer pack, but it doesn't seem to be the problem, anyway. Just curious -- what is the effect of adding/subtracting washers to the vacuum advance? Does a thicker washer decrease the amount of advance, or the other way around? They don't discuss this in the FSM at all.
 
Replacement vac advance pods have different total advances available. There should be a number stamped on the flat linkage arm. IIRC it's advance in crankshaft degrees but don't quote me.

Where's @Halifaxwhen you need him.
 
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