/6 wont start/ run with choke

My 1965 valiant convertible has its original 225 /6. It will not start with the choke connected to the heat operated actuator. When it’s warm I have to hold the pedal to the floor and it’s cranks for a significant amount of time before sputtering resistantly to life. Once running it runs smooth and perfect. At 55 mph you would think it was an electric car it’s so smooth.

I replaced the Carter carburetor that had worn out sloppy throttle shaft bushings and had been sitting for who knows how long with a brand new rebuilt unit. I replaced the brittle old gasket and installed a brand new spring heat operated choke actuator and its doing the same thing. It only starts with the choke wide open and the throttle pedal fully pressed to the floor.

I’m thinking it might be low compression due to valve adjustment, old worn out piston rings could be the culprit. I’m sure it still have valve seats designed for leaded fuel. The odometer is showing 3012 miles and I’m assuming this is 103,012.

I want the engine completely stock and to operate as it should with all the factory components fully functional.

has anyone else had this problem?

before I start chasing things around indefinitely only to have no results I’d appreciate if the forum could point me in the correct direction.

Thanks in advance for any information.

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"New rebuilt" doesn't mean the same thing as "good".

Well, it's always good advice to do a hot compression test. But I once had a slant with an EGR intake that had a crack through base of the intake manifold where it is heated and draws from exhaust gas from the heat riser. It would do the same thing during cranking but wouldn't take full throttle once running without sputtering and blubbering, though.

RustyRatRod said:

"New rebuilt" doesn't mean the same thing as "good".

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The carburetor came with the vehicle. The owner was a local mopar drag racing hero who had passed away.
He had shelves of blowers and tunnel rams with dual quads, random carbs all over his shop and was notorious for being super fast.
The carb carter carb was in the trunk wrapped in plastic and in a box.
His widow told me it ran but had carburetor issues. I opened up the replacement carb and all the internals appeared brand new. The carb appeared brand new in general, bead blasted, shiny everything.
The problem is, it acts exactly the same with another carb so personally I believe the carb can be mostly excluded as the culprit of the issue.
I need to do a compression test but my compression tester disappeared with a lot of my tools on the move to Idaho.

I’ll check the manifold for cracks or leaks too but those usually run better with the choke on don’t they?

Those two things, that’s where I’ll start. then I’ll check the valve lash, worst case I’ll pull the engine and go through it. With bearings, rings, ect.

I was hoping someone had a simple explanation. I just want to drive anywhere, anytime with no problems and to keep it completely stock.

Is this a carter BBS single barrel carb,???. If so the float level might be off. It should be set at 1/4 inch. You have to take it apart to adjust it. It is at the fuel intake, in back of the fitting. You must take the fuel fitting out to set it. Slightly bend the little tab that contacts the back of the needle, very gently, one way, or the other, to get 1/4inch. The needle faces the inlet (back) side of theinlet fitting. After 1/4 inch is obtained, set the choke idle,, and fast (curb) idle.
The choke idle screw should be set to about 1/4inch measured form the back of the acellorator plate. The fast idle screw should be se to1/2 inch, measured on the back.Choke idle screw is the inboard, screw, fast idle screw is outboard screw. Screwe settings are approximate. THis should get it running to where you can adjust it.
Set idle mixture screw (on carb base) about 2 turns out from full in. Do it very gently.

Dave

It might not be the carb . Keep an open mind. It could have jumped a tooth on the timing chain or the dist could be in the wrong position.These things can cause the same symptoms that you are describing .How many miles are on this motor ?

Henchman said:

The problem is, it acts exactly the same with another carb so personally I believe the carb can be mostly excluded as the culprit of the issue.
I need to do a compression test but my compression tester disappeared with a lot of my tools on the move to Idaho.

I’ll check the manifold for cracks or leaks too but those usually run better with the choke on don’t they?

I was hoping someone had a simple explanation. I just want to drive anywhere, anytime with no problems and to keep it completely stock.

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So you tried 2 carbs and it didn't change anything? I think I would move on from the carbs and try something else. Like items mentioned in post #3.

What is the choke actually doing? On a cold engine, depress the gas pedal and check it out with the air cleaner off without starting the engine. Where is the choke plate on an idling warmed up engine?

You can rent a compression tester from one of the larger parts stores for free.

When it finally starts do you have any blue or black smoke out of the exhaust?

Also these are old cars. If you find that car you can just jump in and go and not have problems let me know? ha

Don't know if this help but I had issues with my /6 1bbl. It seemed like we had a vacuum leak. Once it warmed up it wouldn't idle. Put your hand over the throat and it smoothened right out. Went through all the hoses, new choke, intake and carb gasket, adjusted the valves. Went through 3 different rebuilt carbs and still the same issue. Had to set the idle high just to keep it running. I finally sent it to Woodruff carbs (advertised here). Dave Cunningham got it and told me whoever rebuilt the carb was apparently sleeping. It was so WAYYY too lean. I got it back from him and the car runs like brand new. 108K and it purrs. You might want to try that.