Insulating Against Heat on the Carb

-
1969VADart

1969VADart

Well-Known Member
Joined
Aug 19, 2013
Messages
2,498
Reaction score
811
Location
Fredericksburg, VA
Obviously there has been a good deal of discussion on FABO about Edelbrock carbs and heat soak or fuel boiling issues. I am committed to keeping my Eddy carb, so I figured I would pose a question that surprisingly does not have a solid answer here on the forums. Given the following three options to best reduce heat soak or boiling fuel, which of the three would you choose:

1. Phenolic spacer (1/2" due to underhood clearance issues).
2. Wooden spacer (1/2" for same reason)
3. Edelbrock heat insulator gasket (I believe this is about 0.3")

The carb is mounted on a Mopar intake that looks very much like the Edelbrock Performer intake. I have read through a number of the threads that also addresses steps like adjusting floats and such. Those things will probably be addressed in tuning. But the carb will be mounted on one of the three options above, so I was curious what people thought would be the best option? Thanks as always.
 
1969VADart said:
Obviously there has been a good deal of discussion on FABO about Edelbrock carbs and heat soak or fuel boiling issues. I am committed to keeping my Eddy carb, so I figured I would pose a question that surprisingly does not have a solid answer here on the forums. Given the following three options to best reduce heat soak or boiling fuel, which of the three would you choose:

1. Phenolic spacer (1/2" due to underhood clearance issues).
2. Wooden spacer (1/2" for same reason)
3. Edelbrock heat insulator gasket (I believe this is about 0.3")

The carb is mounted on a Mopar intake that looks very much like the Edelbrock Performer intake. I have read through a number of the threads that also addresses steps like adjusting floats and such. Those things will probably be addressed in tuning. But the carb will be mounted on one of the three options above, so I was curious what people thought would be the best option? Thanks as always.
Click to expand...

Phenolic spacer and (most importantly!) block the heat crossover in the intake.
 
I made my own insulator from a 1/2 piece of 8 ply marine plywood it solved all heat related problems, I have since switched to the edelbrock piece with the same results.

Jeff
 
The factory paper style insulators that are about 5/16 thick with brass eyelets in the bolt holes to help keep you from breaking the ears off the carb work pretty well and are or were until recently easy to get at most parts stores. Pretty much any big block Mopar with a Carter or Holley non spread bore 4 barrel from the late 60s to early 70s had one. I never use anything other than a 1/4" ratchet or short end wrench to bolt on a carb. DO NOT OVER TIGHTEN. If I had the room I would go with the largest 4 hole spacer I could get in phenolic.
 
lilcuda said:
Phenolic spacer and (most importantly!) block the heat crossover in the intake.
Click to expand...

I had read about blocking the heat crossover. I was hoping to avoid removing the intake again (would be the third time). I finally got it bolted down and sealed properly. Is there a specific gasket set made to serve that purpose? Thanks.

jeffnmo said:
I made my own insulator from a 1/2 piece of 8 ply marine plywood it solved all heat related problems, I have since switched to the edelbrock piece with the same results.

Jeff
Click to expand...

By Edelbrock piece, do you mean the actual heat insulator gasket? Thanks.
 
If I don't block the heat crossover (mainly because I have reassembled a lot of the top of the motor and am not sure about removing the intake again), am I pretty much assured that the heat soak issue on the carb will not ever completely go away? Has anyone made this work with the Eddy without the heat soak problems and without blocking the heat crossover?
 
Any of the ones you stated will limit the thermal transfer from the engine to the carb. Edelbrock makes that .31" thick one for that reason. A good fan will take care of the radiant heat.
 
Good you brought it up VA Dart. Good info. I need a spacer on mine. I just have the thin paper gasket and have hot soak issues.
Thanks.
 
I am running the OEM style thick paper unit under a 625 Carter on my 68 post. No boiling issues. I do have a hood scoop though so I'm sure that helps reduce under hood temp. The passenger exhaust manifold is non EFE (early fuel evaporation) valve type also. The crossover is open on both intake gaskets. Big blocks are easy to cheat on since they have no water passage. You can cut a piece of tin can lid loosen the intake and slide it between the manifold and head to block the passage. I would be afraid you might get a water leak trying that on a small block.
 
The thick Edelbrock gasket cured all of my woes!

The single most biggest issue is using a thick gasket I between the carb and intake. The factory use a very thick gasket. Often this is tossed aside in favor for the 1/16 paper gasket. This is not good to use for any Carter (& Edelbrock carb.)

The aluminum heats up & cools very quickly. I do not know how fast the center resign body expands and contracts, but the rate is different and IMO, probably leading to its violent end due to the stress of it all.

The Carter/Edelbrock AFB & AVS (and if your lucky enough to have a WCFB) will suffer from fuel perculation pretty easy when the engine runs a bit warm and has a thin gasket. Edelbrock sells a thicker gasket for the square bore carbs. Edelbrock *I believe* has gaskets for the Quadra Jet that are thick BUT may not fit or trim to fit. Off hand, I know of no one making a thick gasket for the TQ. If you know, post it up please!
 
toolmanmike said:
I talked to that dude at the Nats. Looks like a cool product.
Click to expand...

Yeah, i had first seen this spacer on my buddy's 69 hemi fastback when he was running at Maplegrove PA. a few years back. I did the typical heat crossover block off's and then installed it. Great product, great guy too talk with.
 
Will that thicker Edelbrock Heat Insulator gasket (that is like 0.32" thick) work better than one of the 1/2" phenolic spacers?
 
i have edelbrock 1407 750 cfm with 1 inch alumin spacer, dual plane alum manifold on 400cid BB. electric fuel pump.... went to get burger with wife, @90 outside early eve, drove 15 miles parked ate said burger, came out did the hard start, got into the street and starves for fuel (temp at start up on gauge 198 degrees).... drove @ 1 mile and got it cooling and it got better..... DAMN THE ALUMINUM spacer!!!!!!!!!!! when i park the car and come back after 10 min the fuel filter is about bone dry.... QUESTIION^^^^^^ replace the alum spacer with WOOD or PLASTIC ??? does that coolplate do well? I have ^ pack big hood scoop so no problem with spacers and height....
 
Skip the aluminum for street drivers. Sometimes there fine, sometimes there not.
Phenolic resign cools well, wood is best.
 
rumblefish360 said:
The thick Edelbrock gasket cured all of my woes!

The single most biggest issue is using a thick gasket I between the carb and intake. The factory use a very thick gasket. Often this is tossed aside in favor for the 1/16 paper gasket. This is not good to use for any Carter (& Edelbrock carb.)

The aluminum heats up & cools very quickly. I do not know how fast the center resign body expands and contracts, but the rate is different and IMO, probably leading to its violent end due to the stress of it all.

The Carter/Edelbrock AFB & AVS (and if your lucky enough to have a WCFB) will suffer from fuel perculation pretty easy when the engine runs a bit warm and has a thin gasket. Edelbrock sells a thicker gasket for the square bore carbs. Edelbrock *I believe* has gaskets for the Quadra Jet that are thick BUT may not fit or trim to fit. Off hand, I know of no one making a thick gasket for the TQ. If you know, post it up please!
Click to expand...


I like the Holley or Edelbrock 5/16" thick gasket with the split center for dual plane applications... I have no fuel boiling issues...
 
i boil potatoes in my fuel, i can hear it going lean driving...really sucks.... will be using a new spacer soon... thanks all!
 
My 73 Fury wagon with a 400 has a Carter carb and runs like **** when it gets hot. Carb is in tune and super hard to start when when warm and vapor locks a lot too. I run a old Eddy intake (forget the number but it's the one with the the Mopar part number cast into it) and tried a few different spacers and didn't help much....car gets hot under that big hood. It's been stored away for a few years now and when it comes back out it's getting a Holley carb. :glasses7:
 
I've cured similar hot carb issues in the past by both making and installing a semi-ridged, sheet-aluminum plate to shield and dissipate heat transfer from the engine to the carb, and installing a 1/2" phenolic spacer on top of that. Using this combination requires 3 gaskets and longer studs. Be sure that the aluminum plate does not interfere with any linkages or throttle blades etc.. Also, depending on your intake design, you can use an open plenum or 4-hole style spacer. I sourced a one foot by one foot piece of aluminum sheeting from my local hardware store and cut it to fit. It was pretty thin, but still thick enough to be somewhat rigid.

Another successful addition I made was to use a gas filter with the return nipple to circulate the fuel back to the tank. I had to add the return line to the back of the car and a fitting on the sending unit to make this happen.

Having your ignition timing properly tuned helps too.
 
Summit sells some nice fuel line insulation sleeves. If you insulate the fuel line too, it will be cooler when it gets to the carburetor and take longer to reach the boiling point.
 
RustyRatRod said:
Summit sells some nice fuel line insulation sleeves. If you insulate the fuel line too, it will be cooler when it gets to the carburetor and take longer to reach the boiling point.
Click to expand...

Here ya go! Just added it to my wish list at Summit.

Extreme Shield

I'm also running the Edelbrock insulating gasket.
 
BrianT said:
Here ya go! Just added it to my wish list at Summit.

Extreme Shield

I'm also running the Edelbrock insulating gasket.
Click to expand...

Yeah that's the EXACT stuff I was talkin about. Thanks. I also found something different for the RobKat motor I am going to try. It's a heat shield/gasket that's made out.....crap I don't really know. It looks like cork, but it's not, it's hard like wood......but it's not. I will get a picture of it. It's gotta be close to 1/4 thick where the carb actually mounts and the shield extends well under the carburetor. It's a nice piece.
 
You must log in or register to reply here.
-

Back
Top