Vapor lock, I think

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RC92234

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You may be able to buy a 1/4" thick spacer at most of our vendors. You may also need the gasket that has a metal insert between two layers of gasket material. This is to cover the heat passages and stop the gasket/insulator from burning. Again I can't say for sure on the 73 as it's a spread bore (I think). Check NPD's website.

Does a carb spacer go by any other names? lol... Exactly zero carb or carburetor spacers at NPD. Gaskets galore. Took a gander at CJPony: guess they're big on Edelbrock; nothing for the Motorcraft/Holley 4300D. Mr Gasket at CJPony offers a 1" generic ("Fits Square Bore Edelbrock, Carter and Holley 4150 and 4160 Model Number Carburetors") but it's aluminum; not exactly an insulator.

On to the rest of vendor sites
 
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RC92234

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[url=https://ibb.co/ZVjjKXW][img]https://i.ibb.co/zrMMbxG/s-l1600-2.jpg[/img][/url]
You may be able to buy a 1/4" thick spacer at most of our vendors. You may also need the gasket that has a metal insert between two layers of gasket material. This is to cover the heat passages and stop the gasket/insulator from burning. Again I can't say for sure on the 73 as it's a spread bore (I think). Check NPD's website.
Turns out a spacer is harder to find than one would think, but I did locate likely candidates at Classic (was California Mustang). Nothing at NPD, CJP, Ohio or Kentucky or Virginia Mustang nor Ecklers.

Here are two, one ported, one open center; which is the right answer? And now I'm wondering, should I remove the EGR plate? Both of these are 3/8" high.
 

RC92234

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Turns out a spacer is harder to find than one would think, but I did locate likely candidates at Classic (was California Mustang). Nothing at NPD, CJP, Ohio or Kentucky or Virginia Mustang nor Ecklers.

Here are two, one ported, one open center; which is the right answer? And now I'm wondering, should I remove the EGR plate? Both of these are 3/8" high.
It needs to be non conductive material. a thin gasket and an aluminum spacer won't do the job.
 

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DSwan and Stanglover mentioned the insulator spacer that goes between carb and intake manifold, I am reminded I also installed a spacer at same time as the return to tank pump. I recommend the Edelbrock spacer P/N: EDL-9266 at Summit, quality is superior over the Holley Base Gasket P/N: 108-18 at Holley’s web site, I have both. The Edelbrock is much better looking.
I remember going ahead with the return to tank pump at same time as gasket. My fuel pressure was running about 9-10psi before engine was at operating temp and vapor lock would start, I needed to lower pump psi closer to 7psi.
I don’t thing the Carter return to tank pump came on any other Mustangs than the 71 429cj that used a return to tank line and a quadrajet carb.
I would order up the EDL-9266 Divided Heat Insltr and possibly a little longer carb studs from Summit and give that a try before considering a return to tank system or messing with your ignition system just yet.
 
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Well, there is one more alternative option, make your own. You should be able to find and buy a piece of Micarta in varying thicknesses. It is used to insulate electronics and high temp components. I made my own 1" thick insulator spacer for my carb, but then I had access to a mill and boring head. I bought it from an electrical supply wholesaler. It does not have to be too fancy or exact. Hole saws will be sufficient.
McMaster and Carr might be a good company to try. A Google search will come up with other options.
 

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IMG_20220129_123936488[1243].jpg This is the insulation coming up through the power steering bracket. I tried to add another picture of just the insulation, but I can't figure this format out used on the forum. I got it from a friend, and it works nice, you just slide it over the fuel line. I'll try to add the other picture to another post.
 

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IMG_20220129_124137247[1241].jpg Here's just the insulation. I might be able to find out exactly where it was purchased, but I think it's fairly common.
 

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IMG_20220129_123836804[1240].jpg Picture of 1" square tubing used to brace upper control arm to frame so suspension drop doesn't tear up ball joint boots when lifting car.
 

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I believe this will work, the stud spacing and throttle bore measurements are the same as on my CJ manifold.
It doesn't say how thick it is, but appears to be about 1/4".
 

RC92234

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[url=https://ibb.co/ZVjjKXW][img]https://i.ibb.co/zrMMbxG/s-l1600-2.jpg[/img][/url]
I believe this will work, the stud spacing and throttle bore measurements are the same as on my CJ manifold.
It doesn't say how thick it is, but appears to be about 1/4".
Saw the one on WCCC, also -- very disappointing it was out of stock! But in this one for the 4350 series, why didn't you look at the 4300D? In the 4300 series shown on that site, the openings for secondaries are slightly larger than primaries, but in the 4350 series the secondaries are significantly larger. I do not know what the underside of my 4300D looks like, so I don't know which is correct. Also, at least in the 4300 series, the flange gasket is only 1/64" thick. That won't help.

So what do you think of this "Heat dissipation kit" from Holley? Would it fit my 4300D? It's several mixed layers, totaling 1/4"
 

RC92234

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[url=https://ibb.co/ZVjjKXW][img]https://i.ibb.co/zrMMbxG/s-l1600-2.jpg[/img][/url]
Saw the one on WCCC, also -- very disappointing it was out of stock! But in this one for the 4350 series, why didn't you look at the 4300D? In the 4300 series shown on that site, the openings for secondaries are slightly larger than primaries, but in the 4350 series the secondaries are significantly larger. I do not know what the underside of my 4300D looks like, so I don't know which is correct. Also, at least in the 4300 series, the flange gasket is only 1/64" thick. That won't help.

So what do you think of this "Heat dissipation kit" from Holley? Would it fit my 4300D? It's several mixed layers, totaling 1/4"
I've never heard of these folks, but here's a generic, inexpensive, in-stock, phenolic open bore model:
 

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The bottom of your 4300D looks just like the 4350 flange gasket and the gasket on WCCC. You might be able to make the one from Holley work, will, require modifying the gaskets. If you want I'll post a picture of the carburetor mounting flange on the CJ intake manifold.
 

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I've never heard of these folks, but here's a generic, inexpensive, in-stock, phenolic open bore model:
Your carburetor is not a square bore. It is a unique spread bore design. I'm assuming it looks like this:
4300D.jpg
 
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RC92234

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1973 Convertible, 351 4v CJ, C6, Mach 1 Decor options, power: steering, brakes and windows, a/c, Rally Pac gauges, Deluxe interior.
[url=https://ibb.co/ZVjjKXW][img]https://i.ibb.co/zrMMbxG/s-l1600-2.jpg[/img][/url]
The bottom of your 4300D looks just like the 4350 flange gasket and the gasket on WCCC. You might be able to make the one from Holley work, will, require modifying the gaskets. If you want I'll post a picture of the carburetor mounting flange on the CJ intake manifold.
A pic of the manifold would be great. I think I'll continue to look for the one closest to the WCCC version even though the WCCC version doesn't say how thick
Your carburetor is not a square bore. It is a unique spread bore design.
So that's why open bore won't work. Ok.
.
 
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