Carburetor Circuits

[Sniper]

When I did the compression test on my 51 they ran 50-60 psi across the cylinders.  But it runs well, I put it down to sticky rings due to sitting.  I really ought to do the tests again now that I have some miles, and MMO, on it.

[Los_Control]

Just now, Sniper said:

I really ought to do the tests again now that I have some miles, and MMO, on it.

I would agree ... I think is a wonderful idea to do a compression check when you first get your car regardless how well it runs.

Just creates a base line or starting point and as time goes by we have something to look at and compare in the future.

Hoping @keithb7 ran a compression check when he first got the Chrysler.

 

@Sniper my brother ... so much information can be gained from a compression test. What do I know, just a old washed up carpenter.... My first compression test showed a couple over 100 psi, couple between 75-90, 1 at 60 ... To me that suggest stuck rings and dirty valve seats. With mmo & love they are now all above 90 psi

 

When they are all proper within 10 psi of each other and low, My lil pea brain thinks you have a good running worn engine that needs a set of rings.

Back in the day, If you took your car to the Texaco gas station, they would replace the rings in 1 day.

Of course you had to be on top of it, get the needed parts replaced before the pistons had to much slop & ruined the cylinders.

 

I only think that if you get on top of a issue early, creates less damage. I think these cars had weak rings, they would wear out. They would first turn the rings into a oval during power & compression stroke, then they would turn the cylinders into a oval.

 

@Sniper If you are happy with your oil pressure, you can keep it and just re-use the bearings. At least look at them.

Hoping you run a compression check then report it is better.

[Sniper]

35 minutes ago, Los_Control said:

@Sniper If you are happy with your oil pressure, you can keep it and just re-use the bearings. At least look at them.

Hoping you run a compression check then report it is better.

I might very well do another test.  I am tearing down a 230 to build up.  Found a few things I don't like, primarily the water distribution tube was virtually plugged up with crud. 

[Los_Control]

Just now, Sniper said:

the water distribution tube was virtually plugged up with crud.

I assume you will replace it.

Amazing how tough that crud is ... like barnacles growing on a hull of a ship.

What I did with mine is wrong, I just rammed some metal rod down it and cleaned it out.

It actually fixed a issue I think the truck was originally parked for ... overheating.

 

I will try to quote @Plymouthy Adams People do not realize the "laydown" room needed to work on a project.

I can only take apart so much at a time, when cheaply painted & put back together ... maybe I drive it for a year and then pull the motor. I just do not have the room or mental capacity to blow it to pieces & put it back together.

The engine work will come later after is on the road. Hoping the compression equals out, same time the rear seal is leaking ... we all know this engine is being pulled someday. When I only have a engine in front of me & not a full truck.

 

What I meant to say, I think those barnacles growing in the middle of the wdt, actually push it out.

So taking the time to clean out the middle of the tube, the thin metal actually has a place to collapse while pulling it out.

[chrysler1941]

Compression test is good. A leak-down test will tell more about valves and rings.

A simple vacuum meter will tell you everything.  

 

 

 

Jump to 0:44

Edited June 6, 2021 by chrysler1941

[keithb7]

A lot of the issues I am dealing with on my '38 Chrsyler are due to the car sitting so much over the past 25 years. 7000 total miles since the engine and entire car was rebuilt. We've all heard it before, cars were not meant to sit. They certainly deteriorate. I'm seeing some of those results now.

 

Today I will purchase some Marvel Mystery Oil. Put a little in each cylinder, crank the engine over, and let it sit overnight. I'll put some MMO in the fuel tank and then start driving it. I'll perform a complete valve set. Then see what happens to the compression over the next 500 miles or so. Good chance it'll come up I think. I'll see if I can round up a boro-scope too to have a look down in the cylinders.  Worst case scenario it's not a big deal to pull head and manifolds next winter if needed. Lap them valves up nice and pretty. Have a look at cylinder walls in #2 then plan out next steps.

 

In the mean time, I've had a lot of fun and gained more great experience dealing with what this car has thrown at me so far. 

Edited June 6, 2021 by keithb7

[Los_Control]

Kieth I think you are on the right track. Watched your video today about the compression check As far as I know ... your engine is not wore out.

If you picture it in your mind, we have tools to clean the ring grooves on the pistons.

Then install the rings they need to rotate freely while working.

 

Back then we had rings made of different materials. Today we have rings going 300k miles.

 

If you picture your ring stuck to the piston from sitting, it will not rotate in the groove like it should. can be just a 1/2" section, but will prevent it from opening fully & spinning in the groove as designed.

Is it dissimilar metals?  I dunno ...

 

Thats where mmo will help you, but it takes patience.

Get the big jug, fill all the cylinders to overflow. Then let it sit.

I let mine sit for 2 weeks at a time ... you wont like that ... maybe 5 days? If you turn the engine over all the mmo gets pushed out of the exhaust. Just a waste of time & product ... waste of time.

 

No guarantee this will fix it, but probably best chance you have ... short of tearing it down & replace the rings.

[Sniper]

I was doing yard work today, 8 hours worth, yay.  Anyway, my push mower will occasionally not vent the gas tank and when the vacuum in the tank gets high enough the engine will stall for lack of fuel, made me think of your issue.  Any chance you can pull the gas cap when it acts up and listen for a whoosh sound? 

 

I am not going to do a compression test this weekend, too dang wore out now.  Mid 90's out and I spent all my energy in the yard.  Lost 5 pounds today due to sweating.

[keithb7]

Feels like we are in the middle of summer above the arctic circle here today.  Brr. Cold and windy. 
 

I put some MMO in all the cylinders and fuel tank today. I’ll start driving it this week and continue with treatments, until it’s attitude improves.

 

I’ll continue to focus on cylinder #2 long term. A have faith it’ll free up. 
 

Will try the fuel cap vent idea. The Chrysler is exhibiting many similar fuel issues as my ‘38 Ply last spring. I only have so much time to poke through every possible improvement on the car.  So it takes a while. I’m confident at some point I’ll have it dealt with. The 6V auxiliary pump is a sure winner. Pretty sure I’ll be going there. Worked great for my Plym.
 

The only reluctance I have is all the comments I hear about others with similar Mopars with no issues in 100 degree heat. No auxiliary electric fuel pump. Running cheap ethanol fuel. No carb base heat plate. No phenolic spacer. All stock....I’m skeptical. 

Had  I not been idling for 30 mins in stop and go traffic at 95F, I’d have been fine last week. I am pretty sure I could easily flash up my car and drive in 100F temps at regular speeds.  30 MPH and up, normal driving, and I’d have no problems about vapor lock either. 
 

It’ll all be sorted. I appreciate your comments and support....In time grasshopper. In time it will all be done. 

Edited June 6, 2021 by keithb7

[keithb7]

A brief update:

 

I put Marvel Mystery Oil in all 6 cylinders and let it soak for a full week. I put extra, extra oil down in #2. I flashed it up this morning. Burned off the oil. Went for a drive. Did a compression test on #2. Still 75 psi. I will add MMO in the fuel tank indefinitely and see if the situation improves.  Next step is a full valve set. Will report the results.

Edited June 13, 2021 by keithb7

[chrysler1941]

I always thought Marvel Snake Oil was solely an American phenomenon.

[Sniper]

MMO in the oil is the best long term degummer.

 

And no, it isn't snake oil.

[Los_Control]

Just now, keithb7 said:

A brief update:

 

I put Marvel Mystery Oil in all 6 cylinders and let it soak for a full week. I put extra, extra oil down in #2. I flashed it up this morning. Burned off the oil. Went for a drive. Did a compression test on #2. Still 75 psi. I will add MMO in the fuel tank indefinitely and see if the situation improves.  Next step is a full valve set. Will report the results.

Kieth sometimes I feel like the old movie actor Forrest Gump, I'm not a smart man. 

I certainly am no mechanic.

 

My idle brain thoughts .... first of all we know that motor is in pretty good shape, at least we think it was rebuilt with 8k miles on it.

 

Are the other cylinders improving? .... what is the highest cylinder now? My lil pea brain I think a motor was built or re-built & all cylinders are created equal.  They all have same mileage & use.

 

I think that the highest compression of cylinders sets a threshold of where the rest need to be.

The example is mine has a few at 110 psi .... while some came up after use and getting close.

iirc, your video did not show any over 100?  Or was close to it ... been a few day since watching it ... that was my impression they all seemed low.

 

If I get a few cylinders over 110 psi  on a truck been sitting in a field for 20 years ... I suspect this car would show more.

 

@keithb7 Plan a video on doing a valve job ... specifically lapping the valves. I am not a smart person, I kinda think this video will fix most your issues ...

[chrysler1941]

9 hours ago, Sniper said:

MMO in the oil is the best long term degummer.

 

And no, it isn't snake oil.

Never heard of it before joining the forum. It's mystery rest of the world has managed without it LOL

[Sniper]

There's a reason for that, top secret American product.  Eyes only, lol.

[knuckleharley]

4 hours ago, chrysler1941 said:

Never heard of it before joining the forum. It's mystery rest of the world has managed without it LOL

I started using it in the late 60's,at the suggestion of the farmer I was buying a 51 Ford panel truck from. It had been sitting for 10 or 12 years,and was stuck. Filled the rear with cinder blocks for weight,pulled the plugs,filled the cylinders with Marvel Mystery Oil,and pulled it around in one of his fields with his tractor,and the truck trans in 2nd gear with no spark plugs or battery.

 

Got it freed up,put the plugs back in it,and it started right up with the starter and a hose running from a small gas tank to the carb. Shut it off,and when I went to start it again to move it,damned if it wasn't stuck again,so we had to pull it around again to get it running.

 

Drove that truck for 4 or 5 years. Was even forced to live in it parked in the woods a few times. Broke my heart to sell it,but I was moving to Colorado to go to gunsmith school,and I knew if I left it at home my father would sell it to the crusher. He HATED old cars.

[keithb7]

@Los_ControlI will perform a valve set, however at this point, it won’t include any valve lapping. Valve lapping means the cylinder head comes off.

 

For a valve set, just the valve covers, fender window, and RF wheel comes off.  
 

My top cylinder recorded 100 psi. Others about 90. Then #2 at 75. MMO is in the fuel tank. We shall run it as is and see what develops. As mentioned the engine has been laying unused for many of the past 25 years, since it was rebuilt. MMO certainly won’t hurt while I drive it this summer. 

 

The cylinder head might come off in the future. Not now. If the head comes off, I start thinking about the oil pan. Unbolt the rod cap on #2 and slide the rod and piston right out the top. Then I’d learn exactly what’s going on. Maybe followed by a hone,  rings and reassembly. That’s not happening this cruising season. Unless the engine self-schedules the job. 
 

Finding an engine with unknown time in a field and recording 110 psi, is akin to winning the lottery in my opinion. Certainly not a normal occurrence. 

[kencombs]

9 hours ago, keithb7 said:

@Los_ControlI will perform a valve set, however at this point, it won’t include any valve lapping. Valve lapping means the cylinder head comes off.

 

For a valve set, just the valve covers, fender window, and RF wheel comes off.  
 

My top cylinder recorded 100 psi. Others about 90. Then #2 at 75. MMO is in the fuel tank. We shall run it as is and see what develops. As mentioned the engine has been laying unused for many of the past 25 years, since it was rebuilt. MMO certainly won’t hurt while I drive it this summer. 

 

The cylinder head might come off in the future. Not now. If the head comes off, I start thinking about the oil pan. Unbolt the rod cap on #2 and slide the rod and piston right out the top. Then I’d learn exactly what’s going on. Maybe followed by a hone,  rings and reassembly. That’s not happening this cruising season. Unless the engine self-schedules the job. 
 

Finding an engine with unknown time in a field and recording 110 psi, is akin to winning the lottery in my opinion. Certainly not a normal occurrence. 

I think you have a good plan!

 

FWIW, my guess is that #2just by chance had an open valve and a piston somewhat down in the bore  when it was parked and developed some surface rust on the cylinder wall.  Driving may well  polish it enough to renew the ring seal. 

 

One test you may consider is a leak down.  One doesn't really have to have a true leak down tester to find out some info though.   Make or buy an adapter to screw into the spark plug hole and allow attaching an air hose.  Old plug shell with a airline quick connect male  halt welded or brazed in will work.  Use a regulated air supply, 15/20 PSI is plenty and makes holding the engine from rotating much easier.  Attach the air supply ti the adapter with the piston at TDC compression,   and listen for air at the carb inlet, exhaust pipe and oil filler.  That simple test will expose the source of the leak.

 

Or you can go to Harbor Freight and buy the Leakdown Test Kit.  Not expensive,

https://www.harborfreight.com/cylinder-leak-down-tester-62595.html

[Los_Control]

8 hours ago, keithb7 said:

Finding an engine with unknown time in a field and recording 110 psi, is akin to winning the lottery in my opinion. Certainly not a normal occurrence. 

I think you are right 

When I get done farting around with it and actually drive it, am hoping the other cylinders improve more .... even if they do, I hope to get one year out of it and pull the engine. If for no other reason replace the rear main seal that is dripping now, expect it to be a flood after some miles.

 

Adjusting the valves is always a good idea. If one was adjusted to tight, that would affect compression. If the valve could not close and seat all the way.

If too loose they would clatter but not really affect compression .... assuming they are seating.

Thats where lapping them would come in handy. You visually inspect the cylinder while in there make sure no damage is being done while you drive it.

As long as you do not let a-d-d kick in, and make it a bigger project then planned.

I just picture a engine sitting for a long time with the valves open, will build up corrosion on the seating surface ... A small thin amount would cause low compression.

 

I feel valves are not really the issue, it is stuck rings that are not opening fully and sealing ... what do I know though.

 

The mmo in the fuel tank will lubricate your accelerator pump, help clean the carburetor, lubricate the valves etc ... will be a good thing.

 

While adding it to the crank case will lubricate the rings along with internal parts of the engine. Wont hurt a thing, just cost extra and normally just not needed.

When I was a kid pumping gas at the local texaco, I would add a quart of atf while changing the oil on a dirty gummed up engine. Drive it a few hundred miles and repeat it again then change oil again with pure oil no atf ... would really clean a engine out. Basically all the mmo is doing, atf is cheaper.

 

 

 

 

[Los_Control]

I was also wanting to add seafoam to the list of products to try. I have talked to a few real mechanics and they think seafoam is a good thing.

Again you can add it to your fuel, or read the instructions I believe there is a procedure to follow for adding to the oil.

Change the oil, add seafoam, run it at 1200 rpm for 15 min then drain the hot oil and add fresh.

I have done this with my daily driver chebby truck adding it to the fuel, but not in the oil ... just not needed, again atf will also do this.

 

That might make a interesting video also, A product review. I watched one youtube vid of a guy trying it on a old ford ranger. Just gummed up from no oil change abuse ... it was blowing black smoke out the tail pipe with the seafoam in it ... it really was cleaning. And it was a better running engine when finished.

Something you can do in a afternoon, compression check before ... run the seafoam, then compression check after ... see if it improves?

Snake oils do not fix mechanical problems, but gummy & sticky rings it might help.

I would rather experiment on your engine and not mine 

 

[keithb7]

Suppose a guy took the end cover off the coil. Found some exposed wire strands. Suppose they were intermittently touching and grounding to the metal housing? 
 

Maybe, maybe we’re on to something related to a mis-fire here. 

 

 

Edited June 15, 2021 by keithb7

[keithb7]

For reference, here’s what bad looks like. It is imperative that the wire from the ignition switch cleanly, firmly attaches to the rear of the stock coil. Its hidden under the armor and rear coil cap. Rear cap is easily removable. You can’t have old cloth shield threading away. No exposed bare wire strands. 
 

Spare coil and parts that came with the car came in very handy. 
 

 

 

[Young Ed]

It's not the easiest but you can uncrimp that armored cable from the back of the ignition and replace that wire. 

[Captain Neon]

So where does one pick up a phenolic spacer for a 23" L6?

 

[greg g]

Langdon has them in a few sizes and thickness for not much money.