1939 Plymouth Coupe P8

[smallfoot]

Hey that looks purty snazzy! Congrats on the ride...

 

[1952B3b23]

Thanks guys.

I had never painted anything before so i was a bit nervous that i'd get runs everywhere and it end up looking like crap. I think thats why people get all worked up. If it ends up looking bad its the first thing everyone sees.

Yea fixing stuff twice is pretty annoying. Speaking of that.... i should of replaced the thermostat when i fixed the gasket cause just last night i got half way down my street and my temp gauge was soaring! Luckily i noticed and turned around right away. I then shut the car off and let momentum carry me back into the drive way. Pushing the car back up a slight hill into the garage wasn't much fun I had replaced the thermostat about 5 years ago when the engine was still in my '52 Dodge truck and it seemed to be working well until yesterday.

-Chris

 

[1952B3b23]

I've been having some weird problems with the car for about a week and a half now. Once the engine is up to temp (about 180) if i shut off the car it will not start again until its cooled off. It simply cranks and cranks and will not fire. When the engine is cold the car starts with ease. A couple revolutions and it's up and running. It idles fine and doesn't sound like its missing or anything. When driving the car it feels like it has real good power, it actually surprised me when i was cruising around at 50 comfortably. It accelerates well and the engine has no funny noises. Here's the stuff i've tried so far:

1. My first suspicion was vapor lock so i took the air cleaner off the carb, looked down the throat, and gave the throttle a few quick blips. The accelerator pump is working like it should and giving good squirts of fuel. The carb was also recently rebuilt.

2. Tried using starting fluid to get it going, again it just cranks, doesn't even make sounds like it wants to fire.

3. Removed each spark plug wire and held it about 1/4" from the cylinder head. Crank the engine over and see a good blue spark jump the air gap to the head.

4. Then check each spark plug gap and make sure each one is firing. All seems well there.

5. Removed the distributor cap and inspected for cracks. Cleaned the metal contacts on the inside of the cap and cleaned the contact points on the rotor.

6. Inspected the breaker points and they look to be a dull gray color, no pitting or burning. The rubbing block does look a little worn though. I also set the point gap to .020".

7. I've inspected the plug wires and they all still look decent. While the car was running i reached over to work the throttle linkage which passes under the plug wires and i got a little bit of a shock. I had some rubber work gloves on and im pretty certain i didn't touch any of the metal parts of the spark plug or plug wire. So maybe the insulation has degraded and im losing voltage to my plugs, especially as the resistance of the wire goes up with the added heat from the engine.

8. I replaced the distributor condenser. That didnt fix anything.

9. I tried a different ignition coil, no luck.

10. I reset the static ignition timing to 2 degrees before TDC. I thought maybe the timing was to advanced and causing it to not start when hot. I ordered a timing light so i should be able to double check the setting sometime this week. This didn't do anything to fix the issue.

11. Found out my vacuum advance isn't working. It's an issue but shouldn't prevent the car from starting when hot.

Since i just finished putting the car together i had replaced all the wiring and new battery cables (2 aught welding cable). I also have a 6 volt battery charger so i make sure to keep the battery up to snuff at all times when trying this. The starter seems to crank the engine fine when hot so i don't think its a slow crank issue. I have no idea how old the plug wires, cap, rotor, and points are. So i think my next job is going to be to replace those items and see what happens. At this point im stumped and since that stuff really isn't all that expensive it's worth a shot. I also ordered a 5/8" phenolic carb spacer from Tom Langdon. I still need to install that, but i really don't think fuel delivery is my issue. It can't hurt to insulate the carb from all that heat though. Whatever it is it affects all cylinders at the same time once the engine is up to operating temp. If i run the engine for two minutes, shut it off and try again it will fire right up with ease. I apologize for the really long post but i've tried to be as thorough as possible with this and give you guys as much background as i can.

Does any one have any other ideas?

Thanks in advance,

-Chris

 

[DJ3100]

Wish I had something to add, but it seems like you have it covered.

I can sympathize - trouble shoot everything and it still doesn't work. I gotta admit, it makes me feel a little better to know I'm not the only one with goofy mechanical problems.

 

[1952B3b23]

Wish I had something to add, but it seems like you have it covered.

I can sympathize - trouble shoot everything and it still doesn't work. I gotta admit, it makes me feel a little better to know I'm not the only one with goofy mechanical problems.

Yea it's starting to get pretty frustrating. The bottom line is theres got to be something causing this and i need to figure out what. I was really hoping for a straightforward fix.

 

[1952B3b23]

Well i think i finally solved my hot starting problem. I tried a new distributor cap and rotor and that didn't do it. At that point i was getting so frustrated that i decided to remove the distributor so i could look at the points a lot more closely. I'm glad i did. When i was slumped over the fender of the car trying to look closely at them they looked to be in good shape. Once i looked at them on the bench it was easy to see little pits in the surface. I swapped them out and got the engine started back up. Then i put my timing light on it and got it timed. Went for a few spins around the block to get the engine up to operating temp (180*) came back and shut off the car. Immediately tried starting it back up and she fired!! Less than a few revolutions of the starter and it was running. So then i took it out for a little bit longer of a drive, came back and let it sit for 5-10 minutes, tried again and she started right up. I was pretty excited since i've been fighting this for awhile now.

On Sunday i installed a 5/8" phenolic spacer under the carb to help with heat soak. I got the spacer from Tom Langdon. I figured it cant hurt to isolate the carb from all that manifold heat.

-Chris

 

[Torchie]

Glad to read that you got the starting problem sorted out.[cl
Points can be interesting. I've seen some that have been filed down so much you wouldn't think that they could work and other that look brand new that don't spark worth a darn.
Get to driving and watch out for the curbs with those white walls.[ddd
Torchie

 

[DJ3100]

I had forgotten what a pain points can be. Haven't had any for decades. Good to know you got it figured out.

 

[1952B3b23]

Thanks guys. I've been looking at the Pertronix Ignitor Kit for these cars. It does away with the points and condenser, and gets replaced with a little electronic module in there. I would also switch to the coil which they recommend, apparently puts out 40,000 volts instead of 20,000 from the stock coil. For now though im sticking with what i have. I can always do upgrades this winter.

The points really through me for a loop. I had checked the spark at the plugs over and over when the engine was hot. All looked well to me. Im glad i finally got fed up and took the distributor out to have a look. If your eye sight is less than perfect grab a magnifying glass lol.

I hear ya Torchie. I can't wait to drive again. My rebuilt vacuum advance will hopefully come in today. I love the whitewalls but boy are they hard to keep clean.

-Chris

 

[1952B3b23]

My rebuilt vacuum advance came in today. I sent my old one out to a company in NJ called My Classic Car Trader, LLC. They happened to have a*rebuilt unit on the shelf so they sent me that one and kept mine as a core. I'd recommend using them as the service was good and fast. They also rebuild carbs, fuel pumps, starters, etc., check out the web site:

http://www.classiccadillacwaterpumpsforsale.com/

Hopefully i'll have some time on Sunday to install it.

-Chris

 

[DJ3100]

I gotta admit, never once have I thought about the need to re-build vacuum advance. I didn't know anyone did it or that it could be done. Interesting stuff.

 

[1952B3b23]

So I'm having engine troubles again, before the car wouldn't start when hot. Changed out my points and the issue was resolved. Now it just wont start at all! I'm getting very weak spark. When i pull the coil wire out of the distributor cap and hold it over the head, the end needs to be practically touching the head to get a spark. With the ignition key on and manually pulling the points apart i see a very tinny spark. I almost couldn't see it until i had my face right up against it. The last time i did this test when the car was running alright it was quite easy to see the spark jump the points gap.

I have tried a different ignition coil that i know is good. The points and condenser are brand new, they have about 2 hours of total run time on them. When i go through the trouble shooting steps in the manual everything checks out. Except of course the weak spark at the points and coil wire. I'm wondering if i don't have a bad ground between the distributor and engine block. That might explain why i have very weak spark.

The screw that sticks out the side of the distributor and gets connected to the coil via a wire, is that supposed to be electrically isolated from the distributor body? I'm thinking it is. Last night i connected my ohm meter to the screw and put the other lead on the body and i was reading zero resistance. I also remember that the last time i was adjusting the timing with the engine at idle i got a slight shock when rotating the distributor body.

Any help is much appreciated,

-Chris

 

[Old Iron]

I've had a couple distributors short out and couldn't be fixed. Had to change them out.

 

[bob w]

That electrical connection should not ground against the distributor body. The wire that runs from the points to that terminal can develop internal breaks in some of the wire strands and won't pass much current. Look at the insulation on that wire to make sure it hasn't worn through.

 

[1952B3b23]

I've had a couple distributors short out and couldn't be fixed. Had to change them out.

That electrical connection should not ground against the distributor body. The wire that runs from the points to that terminal can develop internal breaks in some of the wire strands and won't pass much current. Look at the insulation on that wire to make sure it hasn't worn through.

Thanks guys. The more i think about it the more i feel as if its the screw grounding against the body that's causing me all this headache. I know that there's a rubber isolator on the inside of the distributor under the head of the screw. But on the outside its just a nut thats tightened against the body. A couple weeks ago i tightened this up when i had the distributor out to change the points. The friction of the nut on the body could have finally rubbed through the paint and caused a short. I don't know why it would only start acting up now but i very well could of made the problem myself without even knowing it.

Regardless i'm taking the distributor back out and inspecting the screw and all the wires to make sure they are okay. I'll post pictures of what i find. Hopefully it will help other people in the future.

-Chris

 

[sgtpontiac]

Yeah, I'd insulate the screw from the dist body...

Normally they have a thru grommet to insulate it or they have fiber washers that insulate the nut / screw from the housing...so I think you are on the right track...

 

[Bamamav]

Normally they have a thru grommet to insulate it or they have fiber washers that insulate the nut / screw from the housing...so I think you are on the right track...

I think Sarge is right, there should be a grommet there. If the wire is touching the distributor case it is grounding out.

 

[1952B3b23]

I didn't really get to work on fixing the problem but I was able to verify that the screw is grounding out on the distributor body. I believe it's a high resistance short so some current is still getting to the points. That's why I was seeing such tinny sparks. Definitely not enough juice to fire the plugs. I did stop at ace hardware to get some rubber washers. I'll also probably use heat shrink tubing to sleeve the screw where it passes thru the body. I don't know if I'll be able to find a small enough rubber grommet locally.

Thanks for the comments guys,

-Chris

 

[1952B3b23]

Whelp i kind of feel like a knucklehead.... it wasn't the screw grounding to the body after all. Something much more simple, somehow my points gap had opened up to .035" when they should be .020"! I know for certain i had them set at the right gap when i installed the new ones. I have no idea how they would of opened up on there own, the hold down screw was nice and tight.

After pulling the distributor i checked out all the wires and made sure none where rubbing, reset the points gap, put the distributor back in and static timed it to 2 degree before TDC. In a couple hours i was cruising around the block again. Tonight i'll put the timing light on her to get it dialed in. I did learn a lot about how the whole ignition system functions so that's a plus.

Thanks for all the comments and suggestions,

-Chris

 

[Torchie]

Good to hear that you got it running again.
Is .020 a factory gap spec as I usually set my points at .016 ?
That is for SBC and your Plymouth may be different.
Torchie