VCCA Home Forums TECHNICAL - 1945 AND NEWER 1949-1954 Full Power Full Choke

I have a 1951 Styleline deluxe 2 door with a 216, 3 on the tree transmission. The engine starts and idles well with choke at about 1/4 out. When driving, last time out, the engine would lose power at higher rpm. Pulling the choke out further would increase power. By the time we got home I had to have the choke pulled out all the way. In turn when shifting to neutral the choke acts like the accelerator. Meaning when the choke is all the way out the engine revs, when pushed back into about 1/4 way out engine idles fine.

The car has new fuel tank, lines, and fuel filter. Not sure on age of fuel pump. The engine has been previously converted to 12 volts.

Any thoughts on where to start diagnosing the problem?

Thanks!

There are multIple potential problems you need to investigate. The key point is that for some reason the engine is not getting enough fuel and is running very lean. The solution is to find the cause of the lean condition.

I suggest that your first steps are to confirm that the choke and throttle cables are properly connected and adjusted. I know this sounds a little stupid but there have been cases when those cables have been connected backwards.

The next step is to search for vacuum leaks. What vacuum do you read at idle? If the engine is in decent shape you should get at least 16”or 17” of mercury. Is the wiper motor properly connected and not leaking air into the engine? You can water, spray carb cleaner, or WD40 at the carburetor base and intake manifold gasket areas to see if anything is pulled into the engine.

Even though it is a new fuel filter, check to make sure it is not plugged. Just because it is a new fuel tank and lines does not mean there was not dirt in them.

If the carburetor has not been rebuilt recently or has been sitting a one time it is always a potential source of the problem. Plugged fuel passages can cause this problem. Or there could be issues with the float level and needle valve.

Of course the fuel pump can have a hole in the diaphragm. You can check for adequate pressure and vacuum with a fuel gauge.

Thanks much! I will be ordering a carb kit and a fuel pump for starters. I am not sure on the vacuum pressures. I think I will need someone with the right gauges to help me out.

A vacuum/fuel pressure gauge is a very inexpensive investment in diagnosing engine performance. I have seen used ones listed on Facebook marketplace for $10. New ones are $14 at Harbor Freight or $30 on Amazon Prime for a good OTC brand gauge with adapters.

First I would check fuel delivery by removing gas line and turning over engine (catch gas in container)

Regarding this:
"In turn when shifting to neutral the choke acts like the accelerator. Meaning when the choke is all the way out the engine revs, when pushed back into about 1/4 way out engine idles fine."
What carburetor are you running?
I assume it has a fast idle linkage on it, meaning...
When you pull out the choke, it opens the throttle at the same time. So the engine SHOULD run faster with the choke out. It was designed to work that way. :-)

YES. if it is a Rochester carb. it has the automaticc fast idle lever and cam.

Thanks for the reminder. I keep forgetting that later W1’s and the Rochester carbs have a fast idle cam that was activated by the choke.

Thanks for all the replays. How much fuel should be coming out of line when I disconnect line, crank engine, and catch in a container? I will most likely pull carb off too and order a rebuild kit. Any ideas on where to find one. My guess it is original Rochester 1 barrel carb.

Napper2,
I have purchased 2 rebuild kits for Rochester Model B carbs from my local auto parts store. They are made to modern standards to deal with the ethanol gas. They did not contain a new float but everything else is there. My cost was $11.00. You can also find them on eBay.
Jeff

I suggest that you do not guess about which carburetor is on your engine.

The Carburetor Shop in Eldon, Missouri and Mike’s Carburetors in Chehalis, Washington are 2 great sources of high quality kits plus a lot of good technical support. They have lots of information on their websites to help you identify your carburetor.