Author Topic: 66 carb prob? Something else?????????  (Read 13682 times)

mike

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66 carb prob? Something else?????????
« on: December 17, 2008, 09:23:38 PM »
Ok, 66 coupe autolite 4100. Rebuild 10 months ago. Car used once or twice a week. Car can be sitting for a week or a day... step on the gas once, close plate, step on the gas one more time to pump some gas...turn the key, and it's magic! starts right away. No hickups, no smoke, no gas smell. fast idle kicks on and it's all good. Turn the car off, back on again and no problems. Let it sit for 15 minutes, and it's a whole different ball game. It does not turn...and when it does after 10 or 15 seconds of turning the key, it starts very sluggish, ruff, with gas smell and some smoke.As it gets going it eventually smoothes out.  I have tried adjustng the choke spring so as to keep it open or closed longer. no luck. I was told that maybe the power valve on the carb was bad. I had the carb checked by the same guy who rebuild it. He adjusted the floats and change the power valve gasket. He idin't think that was the problem as there was no gas sitting in there. "Long story short... ruff starting after sitting warm and sitting for some minutes?????
Thank youuuuu

66GTKFB

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Re: 66 carb prob? Something else?????????
« Reply #1 on: December 17, 2008, 11:25:44 PM »
Think about technique. When you start warm, do you hit the accelerator pedal? Do you 'pump it' after a second or two? Do you floor it? Do you start without touching the pedal (recomended technique in the book)? Remove the air cleaner and observe what happens when starting (use a helper to start the car).
Jim

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Re: 66 carb prob? Something else?????????
« Reply #2 on: December 18, 2008, 03:57:53 AM »
With that 4100, don't pump it after the car is warm.  That will flood it. Just slightly push the gas pedal down maybe an inch or so, then start it.  Like Jim said, it's all in the technique of what you do to start it.  If it does get flooded, then push the pedal to the metal and start it. 

mike

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Re: 66 carb prob? Something else?????????
« Reply #3 on: December 18, 2008, 09:19:33 AM »
ok, tried all of the above. starting without touching gas pedal. once all the way before starting. slightly before starting, slightly after trying to crank, all the way after trying to crank, slightly after it starts, couple of times after it starts... sluggish, and then it starts smoothing out.????

Soaring

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Re: 66 carb prob? Something else?????????
« Reply #4 on: December 18, 2008, 05:04:16 PM »
It's flooding if you have a strong gas odor after it starts.  Do you notice a big puff of smoke coming out your tailpipe as soon as it starts?  You may as well just take the carb off and put a new kit in it.  That's what I would do.  Apparently your mechanic friend didn't know what he was doing. 

mike

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Re: 66 carb prob? Something else?????????
« Reply #5 on: December 18, 2008, 07:26:09 PM »
trust me, i've thought of doing that. So i guess we are set on it being a carb problem huh? Also, i gues i should have mentioned this as well, no matter how many times i change the gasket from the manifold to the spacer to the carb (3 times i've removed the carb) i still get some leaking of gas/oil or very dirty gas(blakish) gas from through the gasket. nuts are tight. you all think that might have to do with some internal leakish??

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Re: 66 carb prob? Something else?????????
« Reply #6 on: December 19, 2008, 02:20:03 AM »
Yeah, that carb is leaking like a sumbitch.  Overhaul it. 

Don A

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Re: 66 carb prob? Something else?????????
« Reply #7 on: December 19, 2008, 05:42:51 AM »
One part of the problem is easy--Too much fuel--From your description I would guess that for some reason the choke sticks closed as the engine cooks back down.  In other words you don't run it long enough to thoroughly lock the choke open so as it cools back down it is partially closed. 

Be that as it may be--I would do my warm up as you have been, then wait thru the cool down as you have been doing then carefully inspect the card linkage etc seeking causes of binding.  If none found hold the choke open and start and see if you still have the problem

This will establish if it is a choke problem or an internal paroblem such as a stuck needle valve or float

Soaring

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Re: 66 carb prob? Something else?????????
« Reply #8 on: December 19, 2008, 04:57:52 PM »
Well, yeah.....if the choke is hung up, then you will have a problem.  Take the air cleaner off and stick a screwdriver in the throat to hold the choke open then see what happens. 

mike

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Re: 66 carb prob? Something else????????? follow-up
« Reply #9 on: December 20, 2008, 05:16:13 PM »
i have played with the choke plate. I have done it both ways... with the spring housing set in rich, left of the center mark so it closes sooner, and where i have it now, right of the center mark in lean position. The choke plate remains open. It remains open for a good while, so that isn't the problem. When it warms up, i step on the gas once and the fast idle kicks off and the plate is open. I have been talking to a mustang carb guy up in ohio. He first thought it was the power valve...i had that checked and it seemed fine. He mentioned it also sounds like the carb is internally leaking into the intake???

Soaring

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Re: 66 carb prob? Something else?????????
« Reply #10 on: December 20, 2008, 06:03:07 PM »
Yes, that happens when the float and/or the needle and seat allow more fuel into the bowl than the bowl is big.  It overflows into the throat and straingt into the firing chamber.  That carburetor needs an overhaul.  Last time I am going to tell you.    ;D

mike

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Re: 66 carb prob? Something else?????????
« Reply #11 on: December 20, 2008, 06:22:13 PM »
i will. this guy sells his overhauled mustang carbs on ebay. i asked him if he would work on mine. Seems like he knows what he's doing. i am shipping it off on monday. He said i should have it back in no more than 2 weeks. I hope that'll do thw trick. i will let you guys know how it goes.

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Re: 66 carb prob? Something else?????????
« Reply #12 on: December 20, 2008, 07:38:14 PM »
I also overhaul Motorcraft carburetors.  The 2100 is my specialty, but the 4100 is basically the same with another set of venturi.  Now, the 4300 is a bitch to overhaul, so I turn them down.  Good luck with it, and I bet you will be satisfied if the rebuilder actually knows what he is doing.  The measurements of the float settings to the choke settings are miniscule when it comes to getting it right and when you get it wrong.  It's a touch of the fingers that makes the difference.  I don't know how else to explain it. 
Also, to keep the cost of shipping down, use a one price box which is free at the PO.   It is less than 10 bucks one way. 

mike

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Re: 66 carb prob? Something else?????????
« Reply #13 on: January 01, 2009, 10:12:54 AM »
Ok, my carb guy in ohio got my carb,THE CARB IS A C4AF-R,
1.12 VENTURI, WHICH IS FROM A 64 GALAXIE WITH A 390, NOT A 289 MUSTANG. He has not opened it yet. Right off the bat you all think this might have something to do with it not working properly??? diference between the above and a MUSTANG.4100 4 BARREL CARBURETOR.C5ZF-C 1.08 ????
Thanks

mike

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Re: 66 carb prob? Something else?????????
« Reply #14 on: January 01, 2009, 12:00:38 PM »
doing more research here. C5ZF-C is for an early 65 must. 4 speed. what i have now is a C4AF-R for a 64 352 full size 1.12 venturi 600 cfm. for a 66 auto i should have C6ZF-B 1.08 venturi 480 cfm. should i stick with what i have after rebuild??? i can get the C5ZF-C , but that's for a 4 speed, how would that work with my auto and would it make a difference???

66GTKFB

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Re: 66 carb prob? Something else?????????
« Reply #15 on: January 01, 2009, 01:06:20 PM »
The main difference is the jets. Manual transmission equipped cars have leaner main and secondary jets. The other differences are the booster venturiis and the choke cover spring. None would make a significent difference except in mileage.
Jim

mike

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Re: 66 carb prob? Something else?????????
« Reply #16 on: January 01, 2009, 02:35:40 PM »
Also, how does the carb that i have now, the C4AF-R 1.12 600 cfm affect the performance of the car??? compared to a 1.08 480 cfm carb ??

mike

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Re: 66 carb prob? Something else?????????
« Reply #17 on: January 01, 2009, 02:39:18 PM »
Does the larger cfm carb affect how rich the car runs???

66GTKFB

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Re: 66 carb prob? Something else?????????
« Reply #18 on: January 01, 2009, 03:31:10 PM »
The correct mixture by weight of air to gas is about 15 to 1. A larger diameter venturi will allow more air and will require a spesific size jet to get the correct mixture. These jets may not be as large as the jets for the correct application. With a smaller engine, 289 CID vs 352 CID, the engine will, at low rpm, draw a bit more air/gas but the carburetor will have the capability to exceed the capacity of the engine. This is called 'over-carbureted'. Will it work? Yes. Will it work well? No. If you have the cam, distributor, exhaust, etc, to handle the larger amount of air/gas you will have more horsepower. On one of the cars I bought, there was a 1961 390 CID carb (1.12 dia) and it ran well but used a lot of gas. One of the first things I did was put a stock carb (1.08 dia). It runs a lot better (and cheaper) now.
Jim

mike

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Re: 66 carb prob? Something else?????????
« Reply #19 on: January 01, 2009, 03:46:23 PM »
thanks Jim, i'm convinced. the right carb for the right application is the way to go. I will go with the 1.08. I should get it by next week and i'll post my results. I cant wait to have a normal running car. 

 

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