Is this normal or at least not too bad?

-
Steves65

Steves65

Well-Known Member
Joined
Nov 7, 2012
Messages
433
Reaction score
170
Location
Massachusetts
So I am a little worried about the health of my slant...it was rebuilt last year and ran great all summer...now that it is getting cold, when it first starts up, it is running really rough, blowing some grey smoke and the other day I saw a little oil coming out of the tailpipe!

This only happens in the first 5 minutes and then once it warms up, no issues! What I think/hope it is...is the exhaust manifold, the heat valve inside the manifold is seized open...is that my issue or could something else be going on?

Wondering if anyone has had a similar experience?

Thanks,
Steve
 
my 64 valiant does the exact same thing! id be interested to hear an answer on this too!
 
Pretty much normal for an old car on modern fuels. What you think is oil might well be nothing more than soot from the tail pipe and muffler that's been liquefied by moisture in the exhaust at startup. Sometimes it can look pretty bad, but if you're not burning oil it's not a problem...unless a sooty mess on your floor or wall is a problem.

The rough running could be a dozen things, but my first guess is a maladjusted choke, and that could also be the cause of your first problem.
 
It is most likley the choke adjustment as said above. Examine the liquid coming out of the exhaust pipe and see what it is; if it is soot and water (water is a normal combustion byproduct and will condense easily in a the cold exhaust system), then it will be watery and not oily in texture if you rub it between your fingers, and will be carbon black in color. It takes some work to get these older cars adjusted to run smoothly when cold; it is not like a modern fuel injected system.

Look at the carb area and see if there is a long rod coming off of the top area of the carb at an angle down to a small, bowl shaped metal cover held onto the exhaust manifold by 1 bolt. If so, this is the choke action in the 'heat well'. Remove the bolt and you should find that long tod connected to a flat, spiral spring. This is the bimettalix spring that unwinds and pulls off the choke when hot. There is normally a small screw and nut holding it together and a scale with gradations with L at one end and R at the other. You can loosen the nut and adjust so that the choke is richer (towards R) or leaner (towards L).

Let is know if you have this or if there is a 'pod' on the upper side of the carb instead of the long rod to the heat well. The pod choke cna be adjusted too. A pix of the upper carb area would be great.

BTW, the heat manifold riser stuck open would only help cold operation after 1-2 minutes, not hurt it. Being stuck closed would be the issue, but would not effect startup running in the first minute or 2. Being stuck open hurts warm weather driveability.

If you are just starting the car, and letting it idle without touchgin the throttle, that can be an issue too. The choke has to be pretty rich to start, but can become too rich after 20-30 seconds of heating up. Normally, I 'blip' the throttle after 20-30 seconds to drop the idle a bit and let the choke open a bit, and it will run better.
 
I agree that it is very likely an over adjusted choke and soot from it coming out the pipe.

An easy way to verify it before you tear into a bunch of stuff is to remove the aircleaner and then start it up when cold.
When it starts running like crap and "grey smoking" push the choke plate open a little more and see if it makes it smooth out.
If it does, then you need to back off on your choke adjustment.
With a carbed engine it is pretty comon to have to readjust the choke when seasons change.

I hate seeing someone jump into a bunch of procedures because of a symtom without verifying what the symtom is trying to tell you.
Once this is verfied by the choke plate position test, then you can get into doing something about it.
 
TrailBeast said:
With a carbed engine it is pretty comon to have to readjust the choke when seasons change.
Click to expand...
^^^ Yes, this is true. I am thnking aobut goig out and checking mine to day with the temps int her 40's; I leaned out the choke in May for better summer starting.
 
nm9stheham said:
^^^ Yes, this is true. I am thnking aobut goig out and checking mine to day with the temps int her 40's; I leaned out the choke in May for better summer starting.
Click to expand...

That was exactly my point. :)
And finding if that's what the problem is can be easy as manually opening the choke with the car running.
 
Thanks everyone...lots of great information! I am really hoping it is just a choke adjustment...below is what I am looking at
 

Attachments

  • IMG_6702.jpg
    43.7 KB · Views: 326
  • IMG_6703.jpg
    41.8 KB · Views: 323
  • IMG_6704.jpg
    47.9 KB · Views: 317
Yes, that is the older heat well type of choke. See the long rod up to the small lever on the top of the carb throat? If you press the throttle to the floor once (or activate it with your hand moving the throttle linkage), there will be pressure on the rod that will snap the choke plate at the top of the carb throat shut. (The choke plate is the 'flapper' in the top of the carb throat.) As the heat increases in the heat well, the bimetallic spiral spring in the heat well moves and gradually moves the rod to open the choke plate as the car warms up.

At this point in time when you took the pix, if you had pressed or moved the throttle once already, and if the engine is cold at this time, then the choke is not working as the choke plate in the top of the carb is almost vertical (choke is off). That rod being bent is not normal, BTW, and that might be part of the issues.

Also, see the round thing also connected to the same linkage? That is the choke pulloff; when the car is revved up while the choke is still on, it will open the choke plate to let more air in to allow the enigne to rev without getting too rich. You can see it work as you rev the car while the choke is on.

I can barely see the heat riser weight below the carb; it is the older type BTW. (Almost looks like 2 shafts... one rusty and one clean... maybe one holds the anti-rattle spring?) The recommend rust penetrant and lube is at the Mopar dealer and is PN 4318039AC. If the riser flapper is stuck then I would do the following.
- Spray on penetrant and let is set for 30 minutes and then repeat
- After an hour or so, take 2 hammers and tap the shaft back and forth lightly. It may not move at first, but be persistent and keep applying penetrant. Eventually, the flapper shaft will move a bit and will move back and forth a bit as you tap lightly with the 2 hammers.
- Once the shaft moves back and forth some, you can apply some moderate turning pressure as you tap back and forth and eventually it will start to rotate a bit. Keep applying penetrant. Eventually it will free up.
- Note that there are 2 'haripin' style retainer clips in grooves in the shaft in the fornt and back that keep the shaft form moving too far forward or back. The are often gone at this age. Simple hardware store clips will work.

You have a Holley 1920 carb BTW (if you did not know).
 
These engines especially don't like cold ambient temps at start up. It takes a while to warm up the intake and they have a tendency to form carburetor ice. If you have a later model air cleaner housing with a themactor valve and can route a hose to a manifold heat stove it helps too.
 
Thanks guys, I was playing around with it this morning and it definitely looks like the choke, it didn't seem to be pulling in much at all and when I pushed it into the well by hand the smoke cleared right up
 
Good deal, at least it was easy to spot that. If you take the choke spring out of the heat well and it is stuck, you can try loosening up the rust with any rust penetrant but there is a penetrant with lube at the Dodge dealer for this and for the heat riser valve; it is Mopar PN 4318039AC.
 
Beautiful engine. Interesting you have a Holley 1920 (had on my 69 slant). Most early slants had a Carter BBS (my 64). When they work right, the 1920 is a great carb, but there are many poorly rebuilt ones out there.

To get the choke to work correctly, it is critical that the "choke pull-off" is working. That is the little can in the bottom left of your 2nd picture. Remove the vacuum line, push in the little piston, block the vacuum hole w/ your finger, and see if the piston stays in. If not, the rubber diaphragm is torn. Even easier to check w/ a hand vacuum pump. You can buy just the pull-off cheap (ebay).

My understanding is slightly different from post #9. I understand that as soon as the engine fires up, at idle, the choke pull-off should actuate to pop the choke open slightly (manual shows using a drill to measure gap). You shouldn't have to rev the engine. If it doesn't work, the choke will stay too tight and it will idle rich and probably die. You do want the choke fully closed while cranking.
 
^^^ Bill I do believe you are correct. Thanks for the correction. The manual says it controls the choke position after start up. I believe this is at idle only, and is a balance between the choke spring and the choke pull off. The imbalanced position of the choke plate on the shaft is what opens the choke plate as the engine revs up and airflow increases.
 
You must log in or register to reply here.
-

Back
Top