Rough idle concern and a sprinkle of questions

[DCJ]

Hello all, 

 

This is my first time posting to this group... Indeed, my first time taking the step to be a part of any forum (I usually just 'steal' what I'm looking for as a passing observer through targeted Google searching lol).

 

I *finally got my 1949 Dodge Meadowbrook running last weekend, it's been sitting since about 2002. Got it last April on trade for a rifle... Boy was it a real diamond in the rough... I'm legitimately afraid to post any pictures of how well this thing has cleaned up in case the guy want's a trade-back. He told me the engine was seized, and based on how dilapidated it appeared, I was frankly interested in selling it's parts off. Definitely going to keep this guy at this point. Very good looking car, and very, very clean after a toothbrushing (literally). 

 

I'm curious to know if anyone in this group has any opinions on how rough, or smoothly these things are supposed to run, in general. I know that's fairly vague but it idles a bit rough for my taste (and experience). It doesn't try to die or surge, and I've driven it around at fair speeds just to see if it still does it under labor, but it doesn't. It also does not smoke at idle, or leave a trail of clouds in any way when it's driven at speed or under acceleration. It doesn't seem to have an un-even or underpowered feeling to it either, quite the opposite, its got quite a bit of low end torque (to my feeling at least...). It's just got a bit of a concerning idle... Don't know how else to describe it, but it doesn't seem to run rich, or lean, or have any major seal problems. I need to pull plugs tomorrow and verify some of this more closely.

 

This car is 72 years old... Older than my grandparents. I understand these motors are a little off from the silky smoothe operation of todays computerized monstrosities... But I'm not sure how 'off' it should really be.

 

I was also curious to know, if there are any other Coronet, Desoto, Meadowbrook, etc. owners in this forum in Ohio! I'm just East of Cincinnati, but was hoping I might be able to cultivate a couple connections on this end of the country. 

 

I'm curious to know about any car shows I should keep under my cap, the best place to go for any mechanical advice, any suggestions off the beaten path for parts or people in the country under the radar who have stockpiles of random things, etc...

 

Many thanks for any replies, and I look forward to being part of this group!

 

Cheers!

 

 

 

[keithb7]

Welcome! You found the right spot. 
 

The flatheads run pretty smooth. Getting them dialed in and tuned properly is a learned skill set. I like to set a base line and go from there, digging in further to find the cause. 
 

Here’s what I’d do to get that baseline. If you don’t know the condition of the listed items, I replace them.  But that’s just me. 
 

compression test wet and dry

fuel pressure test

Intake vacuum test

set idle A/F mixture with assistance of vacuum gauge

New plugs

New Points & set with assistance of a dwell meter

New Condenser while in there inspect all wires and ground points for good connections

new coil

New plug wires

New cap and rotor

set timing

set idle speed

set valves

What you find in these steps will determine where you’ll go further. 

Here’s my 1953 265ci engine at idle:

 

 

Edited January 15, 2021 by keithb7

[soth122003]

DCJ,

What kind of rifle did you trade? A Barrett? Sweet looking ride and welcome to the forum. From your description The car runs fine when moving, it's just the idle that's rough? If so, either your carb is dirty or you are sucking in to much air or both. If you haven't cleaned the carb yet start with that. Your idle circuit is probably fouled. If after a cleaning, and it still runs rough, use a can of carb cleaner and spray around the carb and it will tell where the leak is. On these old cars, it's one of three things. 

!. bad gaskets or seals

2. nicked, warped or damaged mating surfaces. i.e. carb base to manifold or carb base to middle carb etc.

3. worn throttle plate bushings or idle/air mixture screw. (mine is the bushings)

 

Double check the timing using and light and vacuum gage. Then the condition of all the parts in the distributor and plug wires and plugs. I got mine running smooth but at about 650 rpms to offset the leaky throttle plate bushings.

 

Joe Lee

[rallyace]

Flat head Mopar engines are long stroke engines for lots of low end torque and they have hefty flywheels so getting it to run smooth is not all that difficult. Keith and South have pointed out the things to look at. Parts are readily available from places like Andy Bernbaum, Roberts, and Mopar Pro. You can still find a lot of parts through NAPA, O'Reillys and Rock Auto.  You are in the right place to get good, solid advice. This forum has a lot of folks with decades of experience with these old cars.  Good luck and keep asking questions.  The only dumb question is the one you did not ask.

[Sniper]

13 minutes ago, rallyace said:

they have hefty flywheels

 

That is a no foolin' statement right there.  had one shipped to me, listed weight on the package was 66lbs and I believe it. 

 

One thing that usually gets avoided because it's not all that easy to get to is the valve adjustments and that can make it a bit shaky at idle.  But after sitting for who knows how long Keith's list is a good one to go thru in any case.

[DCJ]

8 hours ago, soth122003 said:

DCJ,

What kind of rifle did you trade? A Barrett?

 

Funny you should ask, actually... 

 

It was a Barrett M99. Had that thing crammed in the safe, and I saw this car up for trade for this guy. Wasn't shooting gun, but the wife-lady thought that the car looked super cool. 

 

After she made the decision that the car would hurt her shoulder less (she's 4'10" and 115 pounds...) we were off to Indiana the next morning lol 

 

Rolled it up on the trailer and brought it home, and it sat in our garage for several months, until we moved to our house now (new house has a dedicated shop for 'toys'). 

 

I'm going to start playing with it more today to see where it gets me. 

 

I'm also having a problem with starting it... I need to jump it to get it going. 

 

It has a 6V battery (fairly new), new starter, new starter relay, new condensor, plugs, wires, dis-cap, capacitor, new points, distributer thumb, etc.

 

I'm looking today for heavier gauge wires for the starter and associated components. I've read up a little , and apparently on these 6V systems, they need heftier main battery cables than 12V systems do. I'm also going to run an additional ground to the starter bolt as well, I've heard that can help tremendously (it's only grounded to the block near the water pump, and just about as far away as you can get from the start itself...). 

 

In relation to the carburator... 

 

Can not having the air filter on it contribute to air flow issues?

And, where is the idle a/f mix set screw for this? 

 

Thanks again!

 

[Sniper]

the Idle mixture screw will be towards the base of the carb, on my carb it's next to where the hard line for the distributor vacuum advance screws into the carb.  It has a spring on the screw, only one like that.  You can see it in my carb rebuild write up

 

http://www.yourolddad.com/carb-rebuild

 

As for the air filter question.  Maybe is the best answer I have.  Some have seen on race engines with a 4bbl a modest increase in hp with a properly designed base attached as it is thought to smooth the airflow into the carb.  How that may apply to our stuff, well only a dyno test can really answer that I suppose.

Edited January 15, 2021 by Sniper
clarity

[Marcel Backs]

If the car was sitting for any amount of time and gas has soured and dried in the carb it may have accumulated some varnish in there. This would be more obvious at idle. A sure way to tell is to give the fresh fuel a shot of Lucas fuel system treatment, take it for a good ride and see how she idles then. I do this to my 39 chevvy every summer and the 235 starts and responds like a new fuel injected model. If the car will be stored for a while, make sure you have run stabilizer through the fuel system. Ensure you use premium alcohol free gasoline at all times. Hope this helps! BTW is this the original woodgraining on the dash? Have a good weekend and congrats on an excellent trade!

Marcel

[DCJ]

Sniper,

 

Thanks a TON, I'm going to save your link!

 

I'm thinking I definitely want to do a rebuild on this carburetor for sure... I see a few seeping areas. There is a spring loaded screw on the 'top' of this thing as well, not sure what it goes to.

 

Can anyone lead me in the right direction for a rebuild kit for this carburetor? I've hunted around a bit, but can't seem to lock down exactly what this thing is. I know it's a Carter... There's also an open screw hole on the top of this thing as well, by the way, does that matter?

 

I'm picking up some stuff today (ride to town is 50min one way...), and I'll try to get a video of it running later this afternoon, maybe that would help you guys out a little...

 

 

Thanks!

 

 

[Marcel Backs]

Pics show a carb needing a serious cleaning and rebuild. Is your automatic choke working properly?

[Sniper]

In the following link, 7th pic down, shows where the carb number is located.  You will need that to get the right info and parts. 

 

http://www.yourolddad.com/tune-up

 

This link has a download for the Carter BB service manual.  It ought to be of use

 

 

Edited January 15, 2021 by Sniper
more info

[Cannuck]

That must have been some rifle ,that is one nice car congrats 

 

[Merle Coggins]

The screw on the top if an adjuster for the anti-stall dashpot that’s inside the float bowl. Looks like another accelerator pump, but not... 

[James_Douglas]

I love those carbs with the dash-pot screw on top that can be adjusted. On both of my Desoto's (1947 and 1949) I took off the stock carb and used a version of the one you have. With the fluid couplings....

 

If you are at a stop sign and hit the gas and then pull out of the throttle quick reversion can kill the engine. The dash-pot is what takes care of this by lowering the butterfly valve slowly. With the mechanical as opposed to the electric dash-pot you can adjust it. It saved my butt when I went to a three speed with a fluid coupling versus the M5/M6 trans.

 

One thing. Almost all of these carbs have emulsion tubes that have deteriorated. When I first got my '47 I fought for a couple of years to get the engine to run silky smooth. I did everything one could imagine. I rebuilt three different carbs to a high level of detail and it still was a little rough on idle.

 

I found, and it cost, a NOS carburetor. I put it on and at idle the car was smooth as glass.  After researching it I found out that the emulsion tubes get chewed up by the decades of leaded gas. The problem is that 99% of the rebuilt units out there never had those tubes replaced. It takes a special too to get it out and in. Not to mention finding the correct tubes.

 

So, the lesson learned is that you can get a rebuilt carb or do it yourself and still not have a carb that is mixing the fuel and air correctly.

 

James

[DCJ]

On 1/16/2021 at 11:50 AM, James_Douglas said:

I love those carbs with the dash-pot screw on top that can be adjusted. On both of my Desoto's (1947 and 1949) I took off the stock carb and used a version of the one you have. With the fluid couplings....

 

If you are at a stop sign and hit the gas and then pull out of the throttle quick reversion can kill the engine. The dash-pot is what takes care of this by lowering the butterfly valve slowly. With the mechanical as opposed to the electric dash-pot you can adjust it. It saved my butt when I went to a three speed with a fluid coupling versus the M5/M6 trans.

 

One thing. Almost all of these carbs have emulsion tubes that have deteriorated. When I first got my '47 I fought for a couple of years to get the engine to run silky smooth. I did everything one could imagine. I rebuilt three different carbs to a high level of detail and it still was a little rough on idle.

 

I found, and it cost, a NOS carburetor. I put it on and at idle the car was smooth as glass.  After researching it I found out that the emulsion tubes get chewed up by the decades of leaded gas. The problem is that 99% of the rebuilt units out there never had those tubes replaced. It takes a special too to get it out and in. Not to mention finding the correct tubes.

 

So, the lesson learned is that you can get a rebuilt carb or do it yourself and still not have a carb that is mixing the fuel and air correctly.

 

James

James, 

 

Thank you so much for the info!

 

I'm attaching a couple before and after shots of my 'quick' rebuild for my carb. Found a kit by Walker that I was able to get next-day. There was a good bit of buildup in it. This car has been sitting. How long, I don't know, but a bit of boiling, scrubbing, new balls and seals, and polishing definitely helped it a lot.

 

I'm actually going ahead and pulling the engine out of my car... Thing's a little rough looking, and I'm a stickler for cleanliness (I'm also insanely BORED). I have several more weeks of random time available to me, so I figure I'll go ahead and do at least a partial teardown. It's cold outside, and I don't have grass to cut (haha).

 

It looks to me like someone has had this engine out at some point, there's multi-colored gasket builder in different areas layered on top of itself.

 

The wife and I are pulling the engine out of this guy between tonight/ tomorrow, but We've hit a bit of a snag on this one.

 

I keep seeing people say that I need to remove the back section of the transmission (just at the crossmember) before I can pull this engine out, but I have a ball and trunnion driveshaft link from the diff to the shaft, and also from the back of the trans to the driveshaft. I have pulled, and pulled, and pried, and pulled some more trying to get this thing off, but no dice... 

 

I was hoping I could just separate the engine in the bay and lift it almost straight out, where it meets the flywheel housing, where the starter inserts.

 

Thanks again!

 

 

[DCJ]

James, 

 

Trying to pull DS away from back of trans...

 

Is there something I'm missing. I have never actually worked on a car with a trunnion type before, this thing will NOT separate. It's like it's been spring loaded by an elephant...

 

Thanks again!

[soth122003]

DCJ,

Easiest way is to remove the bolts from the rear of the driveshaft at the rear differential then push the D/S forward and remove the whole D/S.

 

Joe Lee

[Merle Coggins]

I see that you have your jack stands under the frame so that the suspension is hanging. I can only assume it's the same in the rear. When the axle is hanging down the differential drive flange is the closest to the transmission, making your driveshaft at it's shortest possible dimension. If you jack up the axle it will move rearward, lengthen the driveshaft, and making it easier to remove as there is more room to collapse the slip joint. 

[DCJ]

On 1/18/2021 at 7:43 AM, Merle Coggins said:

I see that you have your jack stands under the frame so that the suspension is hanging. I can only assume it's the same in the rear. When the axle is hanging down the differential drive flange is the closest to the transmission, making your driveshaft at it's shortest possible dimension. If you jack up the axle it will move rearward, lengthen the driveshaft, and making it easier to remove as there is more room to collapse the slip joint. 

 

I did BOTH, I lifted the rear dif, and I also removed the rear first (the bolts holding it in place were NOT studs like the back of the trans, they were standalone sets of bolts/ nuts and came right out!

 

Thank you so, so much! Definitely saved me a bunch of headache.

[greg g]

Couple of the pics of the carb show it with the choke butterfly partially closed and some sort of wire holding it in that position. You cant set the idle air screw or the idle speed if the choke butterfly isn't opening all the way.  This looks to be an automatic choke that has been cobbled with and rendered non working. If you need to secure it, it should be locked down in the fully open position and with the fast idle cam in the linkage is out of the way also.

 

If the choke is not opening all the way it causes a rich mixture too much gas not enough air which will foul plugs causing miss tires.  If the engine won't run or idle with the choke wide open, that suggests a vacuum leak below the throttle butterfly which will lean out the mixture causing missfired, voting under load and increased operating temps.  He easiest way to address the choke problem is with an aftermarket manual choke conversion kit.  Or locating proper parts to repair the auto choke to work properly.

[Ward Duffield]

Hope you have a Parts Manual and a Service Manual by now...