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Motorcraft 4 Barrel Carb
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JGRANTAMX View Drop Down
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Points: 1703 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JGRANTAMX Quote  Post ReplyReply Direct Link To This Post Posted: Jun/10/2019 at 11:16am
Interesting info, there is a link from member Trader at the beginning of this thread to Mikes Carburetor parts for 4300 newer type float, I bought one this morning.

J
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Trader View Drop Down
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Points: 6910 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jun/10/2019 at 2:45pm
So to get that facts corrected.
According to Mike's Carburetor and a Ford mechanic the original 70's nitrophyl floats all absorbed gas over time and sink. 
The deteriorating floats as per the Ford mechanic came from an aftermarket supplier back in the 80's and they were only in business until the mid 90's. This may have been a local supplier and not into the US.
In the mid 90's the floats for these carburetors were no longer manufactured and all supplies basically dried up.
They have just started reproducing new floats in the last few years for these carburetors. They are a new formulation of nitrophyl that they developed in the late 70's or early 80's that are so far floaters and not sinkers.
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LakesideRamblin View Drop Down
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Points: 2694 		Post Options Post Options   Thanks (0) Thanks(0)   Quote LakesideRamblin Quote  Post ReplyReply Direct Link To This Post Posted: Jun/10/2019 at 3:02pm
Originally posted by Trader Trader wrote:

So Lakeside,
I thought I was giving sound advice on preventative maintenance for your Motorcraft carb. I didn't state anything to replace the carburetor.
The other responses seem to state the floats can be expected to fail, as I did.

I still believe it is sound advice. On these carburetors, it is best to replace the floats, accelerator pump, while the carb is running good. When the floats deteriorate the material will start to plug passages ... and the carb will provide poor performance and cost more to clean and rebuild if allowed to get to that stage.

Take the advice or leave it, just my opinion.

You did give me good advice, Trader, thank you.  I'll be ordering the floats you linked!
LakesideRamblin
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JGRANTAMX View Drop Down
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Points: 1703 		Post Options Post Options   Thanks (1) Thanks(1)   Quote JGRANTAMX Quote  Post ReplyReply Direct Link To This Post Posted: Jun/10/2019 at 3:58pm
From Mike's Carburetor Parts description of the replacement floats. "New 4300 4 barrel plastic float. New. 1969-74 Ford products. Fits the 4300 only, NOT the 4350 and cannot be substituted. These are not nitrophyl, but they are made from a type of plastic. Ethanol ready."

J
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scott View Drop Down
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Points: 3502 		Post Options Post Options   Thanks (1) Thanks(1)   Quote scott Quote  Post ReplyReply Direct Link To This Post Posted: Jun/10/2019 at 4:38pm
Originally posted by LakesideRamblin LakesideRamblin wrote:

  The engine also has the original cast iron intake manifold.  I will eventually swap that out with a better one (I know there are several good ones from which to choose).  Saw this number on the original manifold behind the carb:  321748B.  Again, I assume it is the original intake manifold.

The original intake is a good piece, I would bet that it flows better than something like an Edelbrock Performer or Offy Dual port. The ports probably match the heads & gaskets better than any aftermarket intake. But it is heavy cast iron.

Accelerator pump cups are the one problem I've had in my 4300. Black ones, who knows what they are made of, shrink over time & stop sealing. I switched to a blue viton cup & have had great luck, no more problems. Also, if you rebuild a 4300, be aware that it has two needle assemblies ( at least my 70 & 71 do, never worked on a 73), operated off of one float. Both need to be adjusted by the service manual specs. One is high flow, the other low flow. Sort of a clever idea.


Edited by scott - Jun/10/2019 at 4:40pm
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LakesideRamblin View Drop Down
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Points: 2694 		Post Options Post Options   Thanks (0) Thanks(0)   Quote LakesideRamblin Quote  Post ReplyReply Direct Link To This Post Posted: Jun/10/2019 at 6:52pm
Much appreciated, Scott.  Good info.
LakesideRamblin
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JGRANTAMX View Drop Down
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Points: 1703 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JGRANTAMX Quote  Post ReplyReply Direct Link To This Post Posted: Jun/10/2019 at 7:54pm
Anyone interested in buying a new Mike's Carburetor 4300 float can get one for the same price as Mike's on ebay with free shipping.
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JGRANTAMX View Drop Down
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Points: 1703 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JGRANTAMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/21/2021 at 3:44pm
 Follow up on the updated floats they have been discontinued anyone know why? I restored my carburetor with one it has not been used yet.

J
https://www.carburetor-parts.com/Motorcraft-4300-Float--FL18_p_3527.html?fbclid=IwAR0oP5F3I7hasOvRLln6Vyw0rYWR-Gj5ta8RKm_4qfJyeSgxTQpsIrTbUrc


 


Edited by JGRANTAMX - Oct/21/2021 at 3:46pm
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ramblinrev View Drop Down
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Points: 11543 		Post Options Post Options   Thanks (0) Thanks(0)   Quote ramblinrev Quote  Post ReplyReply Direct Link To This Post Posted: Oct/21/2021 at 4:24pm
My guess could be supply chain issue?? Also, can't be too much demand.
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amxron View Drop Down
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Points: 295 		Post Options Post Options   Thanks (0) Thanks(0)   Quote amxron Quote  Post ReplyReply Direct Link To This Post Posted: Oct/21/2021 at 11:11pm
These carbs run a little lean. If you add headers or other aftermarket speed parts you will need to go to bigger jets, 2 to as much as 10 sizes larger.

You can buy jets from Ford, they are not the same as Holleys.
All 2 & 4 barrel Motorcraft/Autolite use the same style jets.

Goodluck,

Ron.
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