Possible issue with IAP type distributor

[49WINDS]

Good evening everyone, I'm in the process of trying to tackle a pertronix electronic ignition conversion on my 1949 Chrysler Windsor and I happened to notice something that looks out of place. I was looking at the weights underneath the breaker plate and at first thought one of the springs was worn out until I pulled it apart further and saw that it actually looks like the cam is worn out on one side. I'm guessing this isn't how it should look? Is it worth trying to find a replacement part or will it still function normally? I'd hate to put it all back together and then find out I need to tear it all down again. Any help would be greatly appreciated!

[Plymouthy Adams]

that will need repaired for proper function you can rely on.....check your cam pin....it appears to look good from the top but the action is from the side...

[49WINDS]

Plymouthy- I looked closer at the pin and it looks a little worn down as well, maybe as a result of the worn out cam. Only question now is can I find parts to fix this or not? Thought I had seen stuff like this before but time to start searching I suppose.

[Dodgeb4ya]

921275 is the part# for that Dist.cam... Dist# IAP4102C-1.....numbers are  out of the 1949 Chrysler parts and shop books.

Autolite cam #....IGS1100RX

Dist shaft with pins IGS1112R

You might end up getting another distributor... cheaper way to go at this point.

Edited August 25, 2020 by Dodgeb4ya

[49WINDS]

Awesome, thank you very much Dodge! This gives me yet another reason to purchase a parts book soon.

[Dodgeb4ya]

here's the NOS shaft..https://www.ebay.com/itm/Massey-Harris-Co-op-More-distributor-Shaft-autolite-IGS-1112R-See-Photos/254290381874?hash=item3b34e34c32:g:FQgAAOSwihldI6dd

[49WINDS]

20 dollars seems like a pretty decent price, that shaft looks a little different but that could just be from it not having everything else bolted on to it.

[Dodgeb4ya]

You need to carefully look at yours before you buy as you know...

I think the Autolite # is stamped into the parts...even though I got the #'s from the proper sources sometimes they are wrong!

Make sure your dizzy # is a IAP4102C-1

That is what's supposed to be in a model C45 1949 Chrysler six engine.

[49WINDS]

That is the correct number indeed so that's good to know it matches. I somehow got the wrong cap from rock auto for it even though I know I selected the IAP style one. Guess that's the least of my worries until I can either fix this cam or find a replacement. I'd have to get it all the way apart to be sure but I think the pins are ok, or at least in better shape than the cam.

[49WINDS]

Well It looks like I might be throwing the distributor back in for now until I can get a new cam for it. The only one I could find so far is on ebay for $192 and there's no way I'm paying that much for it! I do see a couple other types of that same part for under $30 but they state they're for a slightly different dist model. Any idea on if they're compatible with my style or do they have enough difference that they won't work correctly?

[kencombs]

Or, one could disassemble the distributor and weld up the slot and file to shape.   The pin can be done that way too.  Not ideal, but once back together it should work well.  Could be done with MIG I guess, but a torch is neater IMO.

[greg g]

I would think a machine shop could weld that worn portion and put it back in good Nick.  Pin should be repairable also.

[49WINDS]

Thanks Ken & Greg, I may actually look into that route. Even if it just gets me a few months or even years until I could find a more reasonable price on that part it will still be worth it.

 

On another note-I'm slightly confused on how to wire in the pertronix module. It says to connect the black/white wire to the negative side of the coil, the black wire to the ignition switch wire, and to reconnect the distributor ground wire when done. On the old setup it had this yellow wire running from the post on the side of the distributor to the positive terminal on the coil and the red & white wires from the harness going to the negative coil terminal. I'm pretty sure those two wires were spliced in because the electrical diagram I have shows black and green wires running to the coil but even those look to be on different terminals from each other. Question is-which wire do I connect to the black wire of the pertronix and do I still need the wire running from the distributor plate to the positive side of the coil? Is that the ground wire perhaps? (I also did buy the pertronix coil, I just used the old one for the mock up in the picture)

[DonaldSmith]

The Pertronix is wired opposite the standard system.  I made a sketch of the two systems.   

The standard system uses the points to ground the primary circuit of the coil, while the ignition circuit keeps "live" power to the coil.    

The Pertronix system controls the current to the "live" side of the coil, and the coil is always grounded. 

 

If you have the semi-automatic transmission, the interrupter circuit briefly kills the engine to allow for the shifting. 

The standard system uses grounds the points, so no spark. 

The Pertronix system grounds the live side of the circuit, so it needs a 7 ohm resister in the  interrupter circuit to keep from frying anything.  

 

 

Edited August 25, 2020 by DonaldSmith

[49WINDS]

Wow, thanks for the awesome drawing and explanation Donald! My car does indeed have the semi-auto, or the fluid drive transmission, and looking at the wiring diagram it appears that it is the blue wire feeding into the circuit breaker & resistor. I can't help but wonder if it was hooked up incorrectly the old way since it had both interrupt and ignition wires hooked up to the negative side and only the ground hooked up on the positive side. Either way it looks like I'll have to peel back more of the electrical tape to find out what color of wire was spliced to each so I know which one to hook up correctly.

 

Two more questions for you though: 1-do I need to install a 7 ohm resistor in between the coil and interrupter or is that already built into the factory circuit breaker? and 2-do I no longer run the "ground" wire from the positive coil terminal to the breaker plate on the side of the distributor and instead run that to ground anywhere?

[DonaldSmith]

The resistor did not come with the Pertronix stuff.  I will have to look into my records for a source.  Maybe tomorrow.  Yes, run the ground wire from the coil to any good ground.  

 

8-26-2020:  Breaking news: 

I checked my records from 5 years ago, when I installed the Pertronix ignition module. 

Pertronix called for a 7-ohm, 5-watt resistor.  I called their technical gurus and asked if 12.5-watt would be OK.  Yes. 

(I got resister RH0107R000FC02, 12.5 watt, 7 ohm, 1%,  from Mouser Electronics.  Less than 10 bucks, including shipping.  

Edited August 26, 2020 by DonaldSmith
Additional information from the files

[Hamilton]

7 hours ago, 49WINDS said:

Well It looks like I might be throwing the distributor back in for now until I can get a new cam for it. The only one I could find so far is on ebay for $192 and there's no way I'm paying that much for it! I do see a couple other types of that same part for under $30 but they state they're for a slightly different dist model. Any idea on if they're compatible with my style or do they have enough difference that they won't work correctly?

 

I might be able to help.  I have a parts distributor out of a `49 Plymouth (IAP-4103A-1, part no. 1300875).  If it'll work I'm confident we can find a number that's reasonable for both of us.  I'll be out of town until late Thursday but should be available for a few days after that.  I'm in Golden, so if you don't mind the drive you're welcome to come have a look.

[49WINDS]

Hamilton-I'll send you a PM to try and get more details and such. It's great to know there's a member from here in Colorado, I was worried I was the only one!

[greg g]

The main mechanical difference between the 218, 230 engines and the 251 265 is the length of the dist drive the shaft.  There might be a slight difference in the advance curve. But since your advance probably isn't working, a unit with aproperly working system would be a plus.

[49WINDS]

1 hour ago, greg g said:

The main mechanical difference between the 218, 230 engines and the 251 265 is the length of the dist drive the shaft.  There might be a slight difference in the advance curve. But since your advance probably isn't working, a unit with aproperly working system would be a plus.

So in theory would I be safe to try a cam from a different model or year then? I came across an IGS-1100RH for $22 on ebay, as well as an 1100R & an 1100RQ for $29 each. I haven't found the weights or the springs though so I'd probably still have to get the pin fixed on the weight.

[49WINDS]

16 hours ago, DonaldSmith said:

The resistor did not come with the Pertronix stuff.  I will have to look into my records for a source.  Maybe tomorrow.  Yes, run the ground wire from the coil to any good ground.  

 

8-26-2020:  Breaking news: 

I checked my records from 5 years ago, when I installed the Pertronix ignition module. 

Pertronix called for a 7-ohm, 5-watt resistor.  I called their technical gurus and asked if 12.5-watt would be OK.  Yes. 

(I got resister RH0107R000FC02, 12.5 watt, 7 ohm, 1%,  from Mouser Electronics.  Less than 10 bucks, including shipping.  

That's the first breaking news I've been actually excited to read for once! Thank you again for all the information you provided, and now since I have to figure out how to fix the rest of the distributor I won't mind having to wait to order and ship a resistor.

 

On a side note - how happy have you been with your pertronix setup since installing it?

[DonaldSmith]

Pertronix - No dreaded points, condenser, etc.  Running fine for 5 years. 

Lingering fear of sudden Pertronix failure, perhaps rare but sometimes reported.  But with these cars, anything can bite us.  Then there's lightning, meteors, etc. 

Tools for an extended cruise - cell phone, contact number for tow truck service, and credit card.  

[49WINDS]

Good news! I went to a junkyard today and was lucky enough to find the exact same model of distributor that I have. It's a little rusty from being out in the elements but the cam looks to be in much better shape that mine. Plus it was only 30 dollars!

[greg g]

Good score.  Now if you can find an old shop with a Sun distributor machine you can check the advance mechanism against the specs. Set the dwell and check it's ndividual spark patterns.

[49WINDS]

Thought I'd share some pics of the progress I've made.

 

Got the weights and cam swapped over from the junkyard dist.  Also mounted the pertronix module to the breaker plate. I was waiting for more parts but today I got a cap & rotor, as well as the resistor needed for the shift interruptor. Last thing I need is the new gasket for the dist shaft and hopefully I'll be firing this thing back up soon!

 

One interesting thing I found is that after ordering the proper rotor and comparing to the old one I can see quite a difference in size. Think this could've caused a few issues??