New Car Day! 1938 P6 Plymouth Deluxe

[n1gzd_plymouth]

congrats. nice find.

Rebecca

[keithb7]

I will start by admitting I like to research and learn topics before I dive in. I spend a lot of time looking for technical info that my brain craves. Even for old 6V systems from 1938. I must say, Google searches pretty much provide marketing and sales search results for every search I perform it seems.  When I search for technical info all I ever seem to get is options to buy things.  Do you folks have a better search engine for technical searches?

 

I am interested in learning more about head light and horn relays. I'd like to learn the differences. I have some pretty good ideas however want to really dig in. Does anyone have any good Delco-Remy reference books from the 40's-50's and back that cover 6V systems. I am interested in buying a book that covers the specialized subject. There is one on Ebay now that I think suits me well. Thoughts on this one? https://www.ebay.com/itm/Delco-Remy-Electrical-Equipment-DR-324-Operation-Maintenance-Handbook-Book-1950/142921844018?hash=item2146ce4532:g:pjcAAOSwo91biAk2

 

There are 3 relays mounted to the inner fender wall on my '38. One for the fog lights, a headlight relay and likely a horn relay I think. Not 100% on that that yet as I need to trace more wires. The weird part is the relays do not appear to be wired up properly. I'd like to fix that.  I could likely do that pretty easily, but would miss out on the opportunity to learn more technical data that I crave. A couple of relay pics in my '38 are attached.

 

This first one reads: H, B, S. Horn battery, switch I think. This was used for the fog lights.  Seems to be a horn relay. However aren't these designed for temporary use?

 

Second relay shows what I think is the headlight relay. With a fuse. This one seems pretty straight forward. Just the wiring to be replaced as you can see the exposed wire. You can see a third relay in this second photo, the grey box with the red wire twisted on it. This grey relay is where I pulled the headlight harness from. Seems odd.  Like I said, more tracing required so I can figure this out. The car was upgraded to sealed beam headlights. I am unaware of the wiring details required for that but hope to learn. Seems pretty simple. Yet 2 relays for headlights? The grey relay mentioned was only utilizing 2 terminals. The black one has 3 wires hooked up.  Who knows what was done here and why. If I could get a proper schematic I should be able to straighten this out. 

 

There is no wiring schematic in the original 1938 P6 manual. There is a wiring diagram. A layout, but no schematic, which I would like to be able to find. If there ever was such a thing. - Keith

 

 

 

 

 

Edited July 29, 2019 by keithb7

[Merle Coggins]

The first picture certainly looks like a horn relay, and you would be correct on the markings. H=Horn, B=Battery, and S=Switch. I don't know how it would hold up to a continuous use, but it may be fine.

 

The other relay looks like a typical 4 terminal relay, but with only 3 wires? Did you say is for your fog lights? I can't see it, but I would assume that the other end of the fuse connects to another terminal input to supply fused voltage? That would make your B and C the 85 and 86 terminals possibly. If the fuse is connected to a second terminal that would indicate, to me, that the 30 and 85 are connected together and the relay is controlled by switching the ground for the coil (86). Pretty much the same function as the 3 terminal relay for the horn.

 

The third relay also looks like a 3 terminal relay, like a horn relay. It's possible that someone wired it up to the high beams to take some amp load off the headlight switch.

[9 foot box]

   Have you found the ply33.com site?  It looks like Delco is pre 35. Your car is, should be Autolite.  mopar.donsautoparts.com has a few early parts. 

[keithb7]

The engine runs a little rough when cold. Could be many things. However looking in the carb bowl, I decided to start there.

 

I pulled the carb and cleaned it all out. I used  a new carb kit. The carb is a Carter BBS carb from 1954, matching the same year engine. It seems the 1954 Plymouths used these carbs. 

 

When I was reassembling the carb I accidentally snapped the step up fuel metering rod. I tried in vain to find a replacement. I did locate a used BBS carb on ebay for $30 and ordered it.  My carb was missing it’s Id tag. I took a chance on the used carb and hoped the metering rod would be the same. Snapped rod seen in pic. 

 

The carb arrived and I was happy to see the rods appeared identical. I reassembled it, set up the choke, and flashed up the engine.  It’s running better but still not smooth. Auto choke is working well. I’ve got some more troubleshooting to do. I suspect a fuel pump issue. It has an electric pump on it that I keep having to prime. It’s also mounted up too high in my opinion. I will test fuel pressure. Also install a carb vacuum gage and view the results.  

 

 

Edited August 7, 2019 by keithb7

[Bobb Horn]

I installed an electric fuel pump on my 38 many years ago, close to the fuel tank, and down very low, so the fuel filter and pump will always be full of fuel.

The modern electric fuel pumps do a good job for pushing fuel, but are very poor at trying to draw fuel...

[keithb7]

Thanks @Bobb Horn  I really appreciate hearing from other ‘37-‘38 Plymouth owners. I will consider a new pump. 

 

On another note, with my tranny in neutral, then letting the clutch engage, I hear humming. Is this likely the clutch pilot bearing spinning? Likely worn out?  Or am I hearing a couple of straight cut tranny gears spinning together?

 

Little to no experience with this ‘38. None around to compare.  Thx. 

Edited August 7, 2019 by keithb7

[Bobb Horn]

My trans hums also when in neutral for the past several years.      When I installed my 5 speed, I used the throw out bearing from my 38, so I guess that is where the hum comes from.       It has not caused any problems so far.

[keithb7]

By chance does anyone have any old spare Mopar distributor breaker plates? I am in need of the small hex-head slotted bolt that retains the points spring arms, condenser wire  and ground wire. This tiny bolt sits down inside the wall of the distributor housing. A small ¼” wrench is required to loosen it off the change the points and condenser.  My bolt head is rounded off pretty bad and should be replaced.  Not an easy bolt to find. However appear prevalent on most old DPDC products.  I posted a want ad in the classifieds.  It mounts at about 3 o’clock in the photos.  

 

I tried to gather the specs. Hard to work with as its so small. 27 TPI. 3/16 thread length. Thread diameter .018”. 11/64 maybe?

 

Thx kindly. 

 

Edited August 8, 2019 by keithb7

[Silverdome]

Are you sure it's not an 8-32 thread. The body diameter would be .164 and then 32 TPI.

The other option would be a 10-24. The body diameter would be .190 and then 24 TPI.

Edited August 8, 2019 by Silverdome

[keithb7]

On 8/8/2019 at 7:29 AM, Silverdome said:

Are you sure it's not an 8-32 thread.

 

Definitely not an 8-32. Using a hardware measuring display at a store, a 6-32 is the closest diameter standard fastener. However the threads are off.  Also these are machine screws and don’t have the required hex head. 

 

I can see why some folks acquire heaps of spare parts. This little stuff can be a challenge. 

[Merle Coggins]

Are you sure it's not a metric thread? An M5 screw would have a 0.8 thread pitch, which would be pretty close to a 27TPI measurement. And 0.18" converts to 4.57mm. A 4 mm screw would have 0.7 threads. I don't have all of those size thread pitch gauges on hand right now, but I did have a 27 and a 1.0 in my desk and they are pretty close. The 1.0 is slightly off from a 27, when I hold them tooth to tooth. The fit is similar to holding a 27 and 28 gauge together. This makes be believe the 0.8 metric pitch may be pretty close to a 27.  

[keithb7]

These thread checkers at work are handy. I never thought to check a metric option.  A 1938 Plymouth with a metric bolt in it? Really?

 

Seems this is the case. This little fastner is a 4MM diamter bolt.  0.70 threads per MM seems like a perfect fit.  Now I gotta find one. 

 

Thanks for the tip Merle. 

 

Edited August 9, 2019 by keithb7

[Silverdome]

I wonder if this wasn't originally a 6-32 and then somebody upped it to a 4M X .7 somewhere along the way. Was the car always in Canada?

[keithb7]

 

I keep over looking the fact that I have a 1938 car with a 1954 engine. Sorry. 

 

It is a Canadian built car. So is the implanted 1954 228 engine. We’ve formally been metric up here since the early 70’s. I think it was during Trudeau Sr’s tenure. I suspect the distributors back in ‘54 were Canadain built too. Could have originally been metric I suppose. We can do funny things up here. 

 

Here’s the little fella. I located and ordered a new hex head 4mm x 10 mm bolt. I’ll be in my hands tomorrow.  I’ll have to trim the length down. If it works I’ll post the part number here for future reference if needed. 

 

What a riveting thread hey? Lol. All about a micro- sized bolt. Yet it’ll put the car down. It’s important. 

 

 

Edited August 9, 2019 by keithb7

[John Reddie]

keithb7,

 Watch out for this little wire in the distributor that I have highlighted. It carries juice to the points and if it is close or touching the distributor housing as this one is, it will rub the insulation through and short out and cause the engine to die out due to the movement of the breaker plate when the engine is running. It can drive you nuts when it happens if you are not familiar with it. I leaned this the hard way on a winter night at 5 degrees. (I am shivering just thinking about it)?

John R

 

[keithb7]

Thanks for the tip John Reddie I will place it nicely and keep it in mind. 

Well the points bolt is not a 4mm. I crossed my fingers and got the old one re-installed. I have located a good stock one from a contact on line and will put it in when it arrives.

The car is running better. Here's an update as of this afternoon. 

 

Gear two seems to make it sound like an old Mack Truck.  Keep in mind carpet & underlay are all removed so it is louder in the cab.

 

https://youtu.be/mHlEWJQ5_UQ

Edited August 11, 2019 by keithb7

[Sam Buchanan]

Text deleted due to erroneous info.

Edited August 14, 2019 by Sam Buchanan

[keithb7]

@Sam Buchanan you make a valid point. Perhaps I’ll change the oil and get a visual on the oil. After I run new oil for a while maybe send an oil sample to the lab for analysis. That would tell me if bearings were failing. 

 

I drive a 1928 Dodge once in a while. The tranny gears howl pretty good in it too. 

[keithb7]

I found the problem with rough idling. I was looking for a place to hook up a vacuum gauge. I found a spot alright...A pipe plug with a hole in it.

Wonder what maybe was supposed to plug into this pipe plug back in '54? Maybe some type of dash pot at one time? It is a good future tap to 

test vacuum. Maybe I'll tap the hole and install another tiny pipe plug. 

Thanks. Keith

 

https://youtu.be/cfwg-3xpeYI

Edited August 12, 2019 by keithb7

[DJ194950]

I would replace the plug for now but it also begs a question-where is your vacuum hookup for a hose for your vacuum wipers>>

 

Maybe that is where it used to be somehow??

 

DJ

[keithb7]

Vacuum wipers...I hadn’t thought of that. Well before my time.  The wipers don’t work. I hadn’t gotten to that project yet. 

 

I bet you’re right. Wipers...

[T120]

23 minutes ago, keithb7 said:

I found the problem with rough idling. I was looking for a place to hook up a vacuum gauge. I found a spot alright...A pipe plug with a hole in it.

Wonder what maybe was supposed to plug into this pipe plug back in '54? Maybe some type of dash pot at one time? It is a good future tap to 

test vacuum. Maybe I'll tap the hole and install another tiny pipe plug. 

Thanks. Keith

 

 

Possiblly the connection for the manifold drain valve . Used back in the day to correct the problem of fuel pooling in the intake causing flooding.I would probably install a plug.....This is the manifold drain valve on my 1936 DeSoto.

[T120]

... Or the connection for the vacuum wiper motor . ?

[keithb7]

With my vacuum gauge in that intake manifold hole, the needle is rock steady at 20 in/mg. Blipping the throttle the needle quickly drops to zero. Then upto 25-30 in/mg briefely. It soon settles down back to a rock steady 20 again.  Seems really good?

 

I’ve never done a vacuum test on an engine before. I was hoping the gauge would assist me to find the right idle mixture setting.

 

Turning the idle mixture screw in, eventually the vacuum reading starts to drop and the engine sputters. Taking the screw back out the engine settles at 20 again. If I keep backing the screw out the gauge does not change. It stays at 20. 

 

I must do more research on this task. I’m missing something here maybe. 

 

This  1954 228 L6 seems like a pretty solid old engine. I have little clues on how long ago, if ever, it was rebuilt. It has no smoke showing out the tail pipe. I recorded decent wet/dry compression around 100. It starts up very quickly when cold. Oil pressure appears very good on the gauge. Idling and purring nicely here now. I’m feeling a little fortunate with this engine. We’ll see how it performs when I start taking it out in traffic and pulling the big hill home. 

 

 

Edited August 12, 2019 by keithb7