Stymied

F

f balsiger

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1930 stock ModelA out of 20 years dry storage. fresh gas, rebuilt Zenith 2 carb.
New gaskets head and intake/exhaust,carb.
50 pounds compression each cylinder
Strong gas flow.
Electronic ignition
I changed intake manifolds.
Runs well but only with 3/4 choke.I tried 3 good rebuilt Zenith twos with same problem.
I tried opening the choke rod needle valve ,could not flood it.
I have sprayed starting fluid over all external intake omponents with no effect.
I have had model A's for 70 years and worked on them for this length of time but I have never had something like this happen.
What have I not done? FRED 7753782985.
 
What is the problem? Does 3/4 choke mean 3/4 turn open or 3/4 pulled up? Did it run before you put all new parts in? If so, why did you replace things? If not, what was the problem?

A "stock Model A" does not have electronic ignition. Those always make me suspect.
 
I think the first thing I would do is replace the electronic setup with regular points.Strange things can happen if they are set up wrong.Where it has sat around for 20 years I would want to make absolutely sure nothing set up housekeeping in the muffler.A partially plugged exhaust will have a very low vacuum,and will need the air intake pinched down pretty good to suck anything in.Having 50 pounds of compression though means some air is getting in.
 
Follow the instructions in the Les Andrews RED BOOK. Make sure you are measuring 6 volts at the locations he identifies. The other day a fellow could not get his A started and his is a real "runner"....never fails him. He discovered he was not getting 6 volts at the points arm and traced to a poor connection at the key switch.
 
Remove the gas cap to take the possibility of a plugged vent out of the equation.

Is there a modern inline fuel filter installed? Remove it if you do.

Does the gas line flow down hill all the way to the carburetor? I've found A's don't like having the gas run up hill at any point in the fuel line. Not sure why but it seems to make a difference.

Check to make sure your fuel line into the carburetor isn't protruding too far and is pushed up against the fuel filter in the carburetor.

Check your firewall mounted fuel filter to make sure it is clean.

Do you have a pencil filter in the tank? Blow some compressed air into the fuel line to clear any debris that may be blocking it.

I know you said you had strong fuel flow but checking all of the above won't hurt.
 
You might check to see how far the fuel line extends beyond the ferrule where it connects to the carburetor. If too long it can restrict the flow.

It is obvious that it is a fuel problem, not ignition. I don't think you will have to do anything electrical. The advice that others are giving regarding the fuel system is good. Even though you have tried 2 carburetors, there may be some crap getting into the carburetor from the fuel tank that is clogging them up. Or it may be something up steam.
 
running 12v neg ground.
blew all the carbs out and rotated them in today same problem reinstalled stock points distributor same problem. I still think I have a large vacuum leak that I cannot find. Any suggestions on finding a leak. I tried starting fluid.
I have been working on these things for 70 years and this is the most frustrating thing I have encountered.
At least I can still find the garage!
 
You mentioned changing intakes, how did they line up with the exhaust ? Just thinking out loud. I'm pretty sure you checked them and looked them over for cracks.
 
To eliminate the possibility that the exhaust system is clogged, take the exhaust pipe off. To test for a vacuum leak, hook up a vacuum gauge and then crank the engine with the throttle closed, or start it with your choke 3/4 on. If the intake manifold is not the type with a connection for a vacuum windshield wiper, you can drill and tap for one then use a pipe plug after the test. A vacuum cleaner stuck up the intake manifold will clean out the chips and may shed some light on any vacuum leak.

Another idea is to crank the engine with the fuel and ignition off and your hand over the carburetor mouth. You should feel a strong suction on all 4 cylinders.
 
back to the electronic distributor ,10 turns out on choke rod needle valve runs good above 1000 RPMS. wont idle yet but that will happen.
I dont know what I did. the coil gets hot but I can hold my hand on it.
 
10 turns!! You more than likely have a large vacuum leak where the manifold is attached to the block.
 
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