Motorcraft 4300d carburetor heat spacer

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gmqcode

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Having a serious hot start issue with my completely stock 1973 351CJ due to excessive carburetor heat. I have concluded that I need a 1" or smaller carburetor heat spacer for the original Motorcraft 4300D. Searched extensively but cannot locate anything that will fit. It seems that the 4300 has a Holley bolt pattern but the Quadrajet spread bore configuration. My question is, has anyone ever located/used one of these spacers? If so, any help or direction on where I might locate one would be appreciated. Thank you in advance!

 
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Just a thought...could you use the original EGR plate and just block it off where the valve would normally attach? Pic of spacer below if you do not already have.

28j8c60.jpg


 

gmqcode

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Yes, I have the aluminum EGR plate installed but it does not appear to have the heat insulating properties the I need. I wanted to add a phenolic heat spacer to the top of that.

 
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Yes, I have the aluminum EGR plate installed but it does not appear to have the heat insulating properties the I need. I wanted to add a phenolic heat spacer to the top of that.
Here's a thought, the outside base dimensions are they same for spread bore or square bore are they not? Could you buy a square bore insulator and re-cut the secondary holes? All you'd need would be a drum sanding sleeve (or two) on a drill arbor.

I actually made my square bore spacer from 1" thick Micarda, but there are Holley insulated spacers out there. I'll go check my box of bits, I may be able to find a number on a 1/4" one I have.

Question; unless you have a concours car, why would you want to keep that crappy 4300 and not go to a Holley 670 or Quick Fuel 650? ( I think they make a spread bore..... or not!) Do you even need a spread bore? Just asking that question.

EDIT NOTE: Just checked the 1/4" insulator I have and there is no number on it, but it does look like there is sufficient material to open up the secondary bores. I don't have a carb to make sure, but maybe an option for you.

 
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gmqcode

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I thought about making one but I was hoping that there was someone out there who would be able able to point me to a shop or a manufacturer than makes them.

My car is not concours but I do like to keep things as factory original as possible and have already spent a lot of time getting this back to factory condition and running properly. The oddity these days seems to be having the original car at a show as opposed to one that is modified.

 
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I thought about making one but I was hoping that there was someone out there who would be able able to point me to a shop or a manufacturer than makes them.

My car is not concours but I do like to keep things as factory original as possible and have already spent a lot of time getting this back to factory condition and running properly. The oddity these days seems to be having the original car at a show as opposed to one that is modified.
I know what you mean about originality........ to a point. Fact is unless someone really knows, a good carb hidden under an original air cleaner is all but invisible. No-one seemed to notice yesterday when my car won best in class for Original 1970-79's at a show.

It's up to you entirely, but I did have a major overheating problem on my carb before I did two things. 1, make the insulator and 2, block off the heat passage in the manifold from the underside. Not an easy job, but worth it. I could probably take the spacer out or just use that 1/4" one I have. By the way, my car is a 71 351C 4V, square bore with a Holley Street Avenger 670.

 

gmqcode

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I thought about making one but I was hoping that there was someone out there who would be able able to point me to a shop or a manufacturer than makes them.

My car is not concours but I do like to keep things as factory original as possible and have already spent a lot of time getting this back to factory condition and running properly. The oddity these days seems to be having the original car at a show as opposed to one that is modified.
I know what you mean about originality........ to a point. Fact is unless someone really knows, a good carb hidden under an original air cleaner is all but invisible. No-one seemed to notice yesterday when my car won best in class for Original 1970-79's at a show.

It's up to you entirely, but I did have a major overheating problem on my carb before I did two things. 1, make the insulator and 2, block off the heat passage in the manifold from the underside. Not an easy job, but worth it. I could probably take the spacer out or just use that 1/4" one I have. By the way, my car is a 71 351C 4V, square bore with a Holley Street Avenger 670.
Thank you for the advise, nice car!! Gary

 

mach1000

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I had same issues with my 2 barrel 302. Always would percolate after shutting off when up to temperature. Concluded it is mainly due to the ethanol gas and its lower boiling point. Used a phenolic spacer and problem pretty much went away. I may add a gas line insulation but again the spaced pretty much did it. Mine is a 2 barrel and got the spacer over the counter at Auto Zone for about $15. Not sure about your 4V application. Good luck.

 
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1971 Mustang Mach 1, M code, 4 speed.
I thought about making one but I was hoping that there was someone out there who would be able able to point me to a shop or a manufacturer than makes them.

My car is not concours but I do like to keep things as factory original as possible and have already spent a lot of time getting this back to factory condition and running properly. The oddity these days seems to be having the original car at a show as opposed to one that is modified.
I know what you mean about originality........ to a point. Fact is unless someone really knows, a good carb hidden under an original air cleaner is all but invisible. No-one seemed to notice yesterday when my car won best in class for Original 1970-79's at a show.

It's up to you entirely, but I did have a major overheating problem on my carb before I did two things. 1, make the insulator and 2, block off the heat passage in the manifold from the underside. Not an easy job, but worth it. I could probably take the spacer out or just use that 1/4" one I have. By the way, my car is a 71 351C 4V, square bore with a Holley Street Avenger 670.
Thank you for the advise, nice car!! Gary
Thanks Gary. I have to say, this is not the picture I intended to post. I have since added PS and PB, but the carb under the air cleaner looks the same. Without the 1" spacer, it would be far less noticeable.

Looking at the picture of the gasket, I am no longer sure that a modified square bore is possible. The bore centers look very different.

I am adding the pictures I meant to post..... just for the heck of it.

Good luck finding what you need.

Geoff.

I didn't mean to steal the limelight here, only show how a different carb might look in your car. Sorry if it came across that way.

 
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gmqcode

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I had same issues with my 2 barrel 302. Always would percolate after shutting off when up to temperature. Concluded it is mainly due to the ethanol gas and its lower boiling point. Used a phenolic spacer and problem pretty much went away. I may add a gas line insulation but again the spaced pretty much did it. Mine is a 2 barrel and got the spacer over the counter at Auto Zone for about $15. Not sure about your 4V application. Good luck.
That's exactly what I wanted to do but no one makes an insulated spacer for the 4300 Motorcraft. I just ordered the fuel line insulation which I will add also.

 
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Gary, I did a bit of searching myself. You're right, there doesn't seem to be anything for the Autolite / Motorcraft carbs, but there are adapter plate available for Rochester and other makes to go from square bore to spread bore. I believe the bolt pattern is the same as Holley and the Ford manifold. There are phenolic open adapters, big square hole. What I don't know and a question I've asked myself before is; Do you really need the 4 hole type or will an open insulator work the same? Perhaps one of our carb guys can chime in and answer that question. If it doesn't matter that much, then there are insulators out there. The gasket with the SS insert in, or an open one like it, will be needed if your exhaust heat cross-over is NOT blocked off or you'll burn the phenolic.

Let us know what you decide on.

Geoff.

 
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gmqcode

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Gary, I did a bit of searching myself. You're right, there doesn't seem to be anything for the Autolite / Motorcraft carbs, but there are adapter plate available for Rochester and other makes to go from square bore to spread bore. I believe the bolt pattern is the same as Holley and the Ford manifold. There are phenolic open adapters, big square hole. What I don't know and a question I've asked myself before is; Do you really need the 4 hole type or will an open insulator work the same? Perhaps one of our carb guys can chime in and answer that question. If it doesn't matter that much, then there are insulators out there. The gasket with the SS insert in, or an open one like it, will be needed if your exhaust heat cross-over is NOT blocked off or you'll burn the phenolic.

Let us know what you decide on.

Geoff.
The aluminum EGR spacer in in place and I planned on putting the plastic spacer on top of that with the gasket with the SS spacer so I don't think the plastic will melt. The EGR spacer has the spreadbore design so I don't think that the open insulator would be the best option. The heat crossover is not blocked off. Was looking at factory spacers they used for the 351M motors and they look like they might work, but not sure if that intake is the same as a 351C. Thank you for the reply!

 
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Gary, I did a bit of searching myself. You're right, there doesn't seem to be anything for the Autolite / Motorcraft carbs, but there are adapter plate available for Rochester and other makes to go from square bore to spread bore. I believe the bolt pattern is the same as Holley and the Ford manifold. There are phenolic open adapters, big square hole. What I don't know and a question I've asked myself before is; Do you really need the 4 hole type or will an open insulator work the same? Perhaps one of our carb guys can chime in and answer that question. If it doesn't matter that much, then there are insulators out there. The gasket with the SS insert in, or an open one like it, will be needed if your exhaust heat cross-over is NOT blocked off or you'll burn the phenolic.

Let us know what you decide on.

Geoff.
The aluminum EGR spacer in in place and I planned on putting the plastic spacer on top of that with the gasket with the SS spacer so I don't think the plastic will melt. The EGR spacer has the spreadbore design so I don't think that the open insulator would be the best option. The heat crossover is not blocked off. Was looking at factory spacers they used for the 351M motors and they look like they might work, but not sure if that intake is the same as a 351C. Thank you for the reply!
I know that the 351M intake is not the same as the 351C. The deck height on the M is taller, therefore the intake is wider. The bolt pattern for the carb should be the same I would think. Gets to be a pain trying to find this stuff. Lets us know how you make out with it.

There is a guy near here that makes heat proof spacers, but I don't know where exactly he is. He was at a local swap meet a couple of weeks ago. Let me check around and see if I can find him. Why I forgot this, I don't know....... unless it's old age!! I'll PM you if I find him.

Geoff.

 

gmqcode

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Gary, I did a bit of searching myself. You're right, there doesn't seem to be anything for the Autolite / Motorcraft carbs, but there are adapter plate available for Rochester and other makes to go from square bore to spread bore. I believe the bolt pattern is the same as Holley and the Ford manifold. There are phenolic open adapters, big square hole. What I don't know and a question I've asked myself before is; Do you really need the 4 hole type or will an open insulator work the same? Perhaps one of our carb guys can chime in and answer that question. If it doesn't matter that much, then there are insulators out there. The gasket with the SS insert in, or an open one like it, will be needed if your exhaust heat cross-over is NOT blocked off or you'll burn the phenolic.

Let us know what you decide on.

Geoff.
The aluminum EGR spacer in in place and I planned on putting the plastic spacer on top of that with the gasket with the SS spacer so I don't think the plastic will melt. The EGR spacer has the spreadbore design so I don't think that the open insulator would be the best option. The heat crossover is not blocked off. Was looking at factory spacers they used for the 351M motors and they look like they might work, but not sure if that intake is the same as a 351C. Thank you for the reply!
I know that the 351M intake is not the same as the 351C. The deck height on the M is taller, therefore the intake is wider. The bolt pattern for the carb should be the same I would think. Gets to be a pain trying to find this stuff. Lets us know how you make out with it.

There is a guy near here that makes heat proof spacers, but I don't know where exactly he is. He was at a local swap meet a couple of weeks ago. Let me check around and see if I can find him. Why I forgot this, I don't know....... unless it's old age!! I'll PM you if I find him.

Geoff.
Ha yep! Been looking for the air cleaner fresh air hose for 2 years! Can't believe there's not a repo for that. Would be great if you could locate that guy's number or e-mail. I will let everyone know how I end up dealing with this issue when/if I find a solution.

 
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gmqcode, the fresh air hose you need is part of the air cleaner duct and valve. Ford had released some service hoses but they are now discontinued. The Ford service part was 2 5/16" x 3 11/16". gmadrid found a flex duct offered by Crown Automotive with dimensions very close to the Ford duct (2.5 X 3.5) and he reported fit perfectly. http://www.4wd.com/Jeep-Engine-Performance/Air-Intake-Tube.aspx?t_c=74&t_s=6&t_pt=5621&t_pn=croj3231980

Your intake presents a unique problem. It is basically a one year only intake manifold (two if you include the 74 Q Gran Torino/Montego, and new 74 full size Cougar). Most aftermarket sources offered very little since most people tossed em' to get rid of the 4300D and the EGR valve. There was a Ford spread bore phenolic spacer offered for a while on the 72 police interceptor. I ran that intake on a transplanted 429 CJ in a 72 Gran Torino Sport. But it was a one year only application since the 73's with EGR valves changed the intake's. Unfortunately I no longer have it as it went along with all my other 429 "Stuff" when I went back to 351 C's. Because of the EGR exhaust passage none of the 72 spread bore gaskets or spacers would "Footprint" your intake. There was a phenolic spacer used on the mid 80's 460 Econline that may possibly fit on top of your EGR spacer. http://www.ebay.com/itm/OEM-Ford-D6UE-carburetor-spacer-gasket-4-barrel-OEM-Factoryt-Original-351M-400-/252496021123?hash=item3ac9ef8683:g:Oi8AAOSwHoFXq9es&vxp=mtr Ad states 351M/400 but Ford never offered a 4bl on those engines. The fitment is actually for a 460. One other choice if you want to stick with the 4300D carburetor is to find a 71/72 351 CJ intake. No EGR valves or fitment problems as everything (Gaskets, spacers, etc) will bolt right up. Hope there is some info you can use here. LOL

 

gmqcode

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gmqcode, the fresh air hose you need is part of the air cleaner duct and valve. Ford had released some service hoses but they are now discontinued. The Ford service part was 2 5/16" x 3 11/16". gmadrid found a flex duct offered by Crown Automotive with dimensions very close to the Ford duct (2.5 X 3.5) and he reported fit perfectly. http://www.4wd.com/Jeep-Engine-Performance/Air-Intake-Tube.aspx?t_c=74&t_s=6&t_pt=5621&t_pn=croj3231980

Your intake presents a unique problem. It is basically a one year only intake manifold (two if you include the 74 Q Gran Torino/Montego, and new 74 full size Cougar). Most aftermarket sources offered very little since most people tossed em' to get rid of the 4300D and the EGR valve. There was a Ford spread bore phenolic spacer offered for a while on the 72 police interceptor. I ran that intake on a transplanted 429 CJ in a 72 Gran Torino Sport. But it was a one year only application since the 73's with EGR valves changed the intake's. Unfortunately I no longer have it as it went along with all my other 429 "Stuff" when I went back to 351 C's. Because of the EGR exhaust passage none of the 72 spread bore gaskets or spacers would "Footprint" your intake. There was a phenolic spacer used on the mid 80's 460 Econline that may possibly fit on top of your EGR spacer. http://www.ebay.com/itm/OEM-Ford-D6UE-carburetor-spacer-gasket-4-barrel-OEM-Factoryt-Original-351M-400-/252496021123?hash=item3ac9ef8683:g:Oi8AAOSwHoFXq9es&vxp=mtr Ad states 351M/400 but Ford never offered a 4bl on those engines. The fitment is actually for a 460. One other choice if you want to stick with the 4300D carburetor is to find a 71/72 351 CJ intake. No EGR valves or fitment problems as everything (Gaskets, spacers, etc) will bolt right up. Hope there is some info you can use here. LOL
I will give the Crown duct a try seeing as I am unable to find anything else. I saw that spacer on E-bay and shot the guy a few questions, but he never got back to me. Thank you for the great info Steve....

 

rpxr400

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gmqcode - where in NJ are you? I ended up making one last year because I thought my issue was fuel boil. There is no available phenolic spacer available.

It ends up my issue was the carb, so I do not have use for the spacer any longer.

I used the rubber-ish 1/4" gasket that was under the carb as a template, bought 1/2" phenolic material and made my own.

You're in NJ? I'm in Eastern Pa - right across the border. PM me your address and I'll send you the spacer I made.

Just get some gasket material from your local auto parts store and cut gaskets to match.

Here's a pic of the spacer:

https://flic.kr/p/KXsTUL

 
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