The Stovebolt Site Forums The Shop Area Engine Shop New Carb, running ruffffff

Just replaced my carb, a Carter to a Rodchester,from Chevy Duty. It's running ruff, and they asy not to adjust it.I got to run it with the chock pulled out about 1/3 of the way.Is this just a worm up problum, or do I make the call to CD? Thanks Paul

Try turning the idle mixture jet out about 1 turn, noting it's original position so you can turn it back if that doesn't help. If that doesn't do it & you are sure rest of the systems are ok, it's time to call them. At least Half the reman carbs sold are not right. Be sure there are no vacuum leaks. Do you have gaskets between the carb, spacer, & manifold, if it has a spacer?

Yes, I have gaskets in, thinking the same lines as you. Always nice to have another oppion.
Thanks, Paul

If it's only running with choke, then the engine is lean. Most likely you have internal problems with the carb, like improper float height, clogged passages, vac leaks.

Have a carb shop or do it you're self and rebuild the carter and put that back on, the carter is a much better carb,I just got done rebuilding a 235 and installing it in my 52 I rebuilt the Mod B that was on it just to get on the road tell I put her away for the winter ,on the work bench I have a carter YF4480s that I just got done rebuilding and I just ordered a rebuilding kit for a zenith that I got when it gets nice out again I'll play around with both and see which one makes My 235 run better,fuel milage ,etc.
You got a 216 ? You could use a W1 carter I got two,for 35.00 rebuilt one and ran it on my 216 to Kansas city and back good milage and no trouble at all.
Pete

Got me thinking leaks.I only got one gasket under the carb, and the spacer has a gasket, I made,to the manofold. Sounds like a vac leak like Skidmark says......got to try it!

i had a similar problem with my 40's zenith. when i had the insulator off to clean and paint it to match the freshly painted carb i forgot to replace the gasket that goes between the insulator and the manifold.

as for setting the idle mixture i do like the book says. i use a vacuum gage and set it at the highest reading i can get. it will change your idle speed so i had to keep tweaking the both of them until i had ythe idle speed where i wanted it along with the highest reading from the idle mixture screw. i did this on all three trucks and they all work fine with no black spots on the floor from the tail pipes at start up.

Someone educate me: What do the black spots on start-up signify?

I'm guessing running rich or incomplete combustion. Not just a symptom of a cold engine at start-up?

-Michael

mike, you answered your own question. being involved in the operation and maintenance of industrial boilers for 30+ years smoke is a constant and obvious concern with what come out of the stack especially when it comes to burning oil. unlike a tail pipe when it spits it out of a 130' sack seems to get everyones attention quickly. most causes are from a dirty tip which over time will carbon up which will distort the flame and cause incomplete combustion (smoke). improper mixture of the fuel/air ratio occurs due to improper mixing of the two to burn clean. fixing one or the other results in a clean burn. the carb does the same thing except the that the fuel is metered at idle and the air ratio is adjusted with the idle screw to permit the proper mixture. this is not to say that a portion of the fuel circuit isnt dirty thus being a possible cause. what i do get on the floor at start up is condensation until it warms up just like everybody else gets.

Thanks for the detailed response! I love these old trucks, but after just a few years in this hobby, I've definitely come to appreciate the advantages of modern fuel injection and electronic ignition. "Tuning" a carb and points system really seems like voodoo sometimes.

I wish we could add a guage to our dash, labeled "air/fuel ratio", with the magical 14.7 being straight up.

Of course, I think something like that exists, possibly called an Exhaust Analyzer? I'm starting to research one of those. Never thought I'd get so geeked out on old engines!

-Michael

Black coming out of the exhaust is rich on gas.
Blue coming out of the exhaust is burning oil.
White coming out of the exhaust is water.
Grey or more clear exhaust is good.

I like to take my finger and rub the inside of the tailpipe. It should be little or grey in color. If it is black and sooty, then it is too rich. Of course it takes some amount of driving to get the tailpipe to a good color. That's why I would pull the plugs and look at their colors.

Start with some new plugs and make sure the timing and gaps (plugs and points) are correct, cap, plug wires and rotors are in good shape, valves are set right. After running it down the road for 10 miles or so, pull the plugs to check their colors. If you make a change to timing, carb, or anything, clean or change the plugs and drive it again and check the colors of the plugs again. If you think about it, the spark plugs are a part of the combustion chamber. That is the best place to look to see how well your engine is burning fuel.

I like to see the ceramic piece of the center electrode of the spark plug to be a nice brown-tan and grey. The ring of the bottom of the plug can be darker. Sometimes, debris on the plug that looks like molten or boiled crap on one side of the plug (this would take more than a few miles) would indicate a valve is loose in the guide and/or valve seal is bad, and allowing oil to burn. If you have access to a scope that you can look into the combustion chamber and the piston is washed off and clean looking around the edges near the rings, that would indicate oil is getting past your rings.

Let us know what you find.

Mikestem I think that guage you want for your dash is a vacuum guage Rob