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Old 10-19-2014, 08:01 AM   #1
Terry,NJ
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Default Carb story (A and B)

As I have said, My A (Coupe) has been running lousy lately and overheating on hills and I can't find out why. All cyls seem to be firing properly. Compression is lousy but equal. I don't trust my gauge, A 1960s vintage Schauer that reads only 25 lbs . The car starts and runs too good for this to be accurate. Altough, testing the gauge shows it to be ok, there's still the performance angle.
So checking out the dist. shows nothing, I looked at the carb which had recently been rebuilt. Checking the throttle shaft, I found about .005-.007 throttle play/slop in the shaft, Is this too much? It was not bushed.
I removed the A carb. and replaced it with a B carb. Hopefully killing two birds with one stone. There was a reason why the B carb wasn't used before! The engine starts buts seems to run out of gas after about 15 seconds. So what is my problem? Not carburetor at all? is 5-7 mils play too much? Gees! I'd really like to know.
Terry
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Old 10-19-2014, 08:26 AM   #2
Tom Wesenberg
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Default Re: Carb story (A and B)

Throttle shaft play doesn't have much effect at half or more throttle.
How is the gas flow if you disconnect the line at the carb?
Is the filter clean inside the carb?
Did this problem start all of a sudden?
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Old 10-19-2014, 08:55 AM   #3
Mitch//pa
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Default Re: Carb story (A and B)

as tom mentioned the throttle shaft is not causing your high speed troubles but to answer your question yes it is to much play. maybe you can do a leak down test on each cylinder with the rad cap lifted and enough coolant to look for air coming up, plus you can see how your valves and rings are. i suspect you may have multiple problems some being with the motor and the other a restricted radiator. does it have abnormal crankcase pressure when running? you may also have excessive slop in your timing gears have you ever pulled the cover and peaked at the cam gear? hows is the fuel flow? do you have crap in the tank?
along with fuel flow you can also drive it with a spark tester inline to see if it gets weaker or erattic under load..
you need to really start from scratch and do a complete diagnostics. if your engine passes some of the basic mechanical tests,do you have AAA or a trailer? if so bring it down to the shop drop it and iill spend some time on it.

Last edited by Mitch//pa; 10-19-2014 at 09:13 AM.
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Old 10-19-2014, 10:32 AM   #4
Ed in Maine
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Default Re: Carb story (A and B)

Hello Terry, I can read the frustration you are having. It is time to take a deep breath and check over the car from the beginning. I assume you have Model A repair books that will take you through both the electrical and fuel systems. I have been in the hobby since 1964 and this stuff is still not committed to memory.

After all these years, I was not totally satisfied with how my cars ran. They did start promptly and run but always felt there could be more power and idle better. I finally purchased a couple of Model A & B Carb books that took me through the rebuilding process. I used to think that a good cleaning and install a new rebuild kit would get me on my way. WRONG! The books pointed out all the critical passages that had to be open and some are not obvious. The most critical part is the correct feed rate of gasoline into the manifold by the carb. In my opinion, you are wasting your time rebuilding a carb with the jets that are on the market without testing them. The books show you how to build a flow tester out of plastic pipe. You can modify the jet sizes to provide maximum power or the best economy. I picked the middle to avoid a rich mixture and get good all around operation. I was amazed on how quickly my car started and ran with a proper carb rebuild.

If your radiator is partially plugged up with water pump grease and rust, you cannot flush it out with cleaner. You cannot get enough pressure and flow velocity through the plugged tubes to clean it up. You can remove the top tank and carefully rod the contamination to the bottom tank and flush it out. There are several posts on Ford Barn on how to do this.

When I run into problems like this I keep telling myself there is a reason for everything! Good luck, keep us posted. Ed
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Old 10-19-2014, 02:00 PM   #5
Terry,NJ
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Default Re: Carb story (A and B)

Just an update. I tinkered with it a little and wound up "Refreshing" the B carb. after a few hours of messing with it, Basically tearing it down and poking things into the jets and passages, I got it to run. Not the way I like it, but it ran and didn't quit on me. My Vacuum gauge said late ignition timing with a steady needle. However, when it missed, the needle dropped. The problem, I'm pretty sure is not the carb. It's about the same with the A carb. The miss is intermitant. I've got a B dist. Perhaps I'll rebuild it and see how it works.
Another question arose, with my ear next to the engine I could hear some light Thud sounds (Bearings?) Maybe it's time to pull the pan and see what those clearances look like.
Terry
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