Which Carb Spacer/Insulator?

[Zonaman]

Looking to address a vapor lock issue so my chief goal is insulation. I want to insulate my Edelbrock 1406 but am not sure which spacer/insulator to use. It sits on an Edelbrock 2104 intake manifold. Looks like I've got room for 1/2 inch clearance without nay trouble. There seem to be several candidates: the Edelbrock 9266 Heat Insulator Gasket, the Edelbrock 8725 Carburetor Spacer or maybe even the
Edelbrock 9265 Square-Bore Heat Insulator. Perhaps one not mentioned here? What say you?

Thanks

[weq92f]

.

My goal was to reduce the temp of my throttle body and hopefully solve some idle quality issues by increasing plenum size and distance from injectors to runner.

Went with this one from Summit:

https://www.summitracing.com/parts/sum-g1408

Hth,

-klb

[Zonaman]

Apparently, whether or not the spacer is divided, has minimal impact on performance?

[weq92f]

Originally Posted by Zonaman

Apparently, whether or not the spacer is divided, has minimal impact on performance?

Here's a good discussion...

https://www.motortrend.com/how-to/pi...t-performance/

-klb

[HOGDADDY]

I use this. It requires no gaskets too but some have had issues with the metal ferrules. Just be sure there not proud.
https://www.summitracing.com/parts/edl-9266

[Ironangel]

Any Phenolic spacer at least 1/2" thick will help and a 1" thick would help even more. I'd go with the open design to equalize the vacuum on all four barrels of the square bore carb on a spread bore dual plane intake. If you had a Holley 4 corner adjustable carb then a separated or 4 hole spacer would allow fine tuning the four corners. Solid plastic is ok, the composite phenolic spacers insulate the best, they're a bit more expensive but resist heat warpage better than solid plastic. https://www.summitracing.com/parts/sum-g1405?rrec=true I always spray the gaskets with WD-40 before installing them, makes them come loose easier.

[Southcity]

Some great and sound advice from Ironangel!

I installed a 1" composite phenolic spacer on a 454/Edelbrock/Edelbrock setup for the same reason over a year ago, to reduce heat on carb from the intake and it has worked well/served me well ever since. Driven hard on a daily basis.

[SRU1436]

Originally Posted by Ironangel

Any Phenolic spacer at least 1/2" thick will help and a 1" thick would help even more. I'd go with the open design to equalize the vacuum on all four barrels of the square bore carb on a spread bore dual plane intake. If you had a Holley 4 corner adjustable carb then a separated or 4 hole spacer would allow fine tuning the four corners. Solid plastic is ok, the composite phenolic spacers insulate the best, they're a bit more expensive but resist heat warpage better than solid plastic. https://www.summitracing.com/parts/sum-g1405?rrec=true I always spray the gaskets with WD-40 before installing them, makes them come loose easier.

I used this on my chevelle and it works great.

[SRU1436]

Originally Posted by Ironangel

Any Phenolic spacer at least 1/2" thick will help and a 1" thick would help even more. I'd go with the open design to equalize the vacuum on all four barrels of the square bore carb on a spread bore dual plane intake. If you had a Holley 4 corner adjustable carb then a separated or 4 hole spacer would allow fine tuning the four corners. Solid plastic is ok, the composite phenolic spacers insulate the best, they're a bit more expensive but resist heat warpage better than solid plastic. https://www.summitracing.com/parts/sum-g1405?rrec=true I always spray the gaskets with WD-40 before installing them, makes them come loose easier.

Will this open design work on a spread bore carb such as a quadrajet? I have a friend who is not mechanical who is having the heat issue and has a quadrajet on his truck?

[CastIron]

I have a similar setup on my truck, and the Edelbrock 9266 worked well for me too.

[MikeB]

Originally Posted by HOGDADDY

I use this. It requires no gaskets too but some have had issues with the metal ferrules. Just be sure there not proud.
https://www.summitracing.com/parts/edl-9266

I have used several of the #9266 over the years. Best to smear a little light grease on the mating surfaces if you want to re-use them.

[jmking9]

I just had to put one on my 71 k10 that has a new Edelbrock 1406. I needed one that was .5" because 1" would have been too tall. I went with the Trans Dapt pt#2180 So far, it has 100% fixed the usual Edelbrock fuel bowl boiling issue.

[HOGDADDY]

Originally Posted by MikeB

I have used several of the #9266 over the years. Best to smear a little light grease on the mating surfaces if you want to re-use them.

Thanks for the tip.

[HOGDADDY]

Whichever you choose you will need new longer manifold/carb studs to match.

[Zonaman]

Going with the 8725. Any idea what the torque might be on that? I'd hate to get too aggressive and crack it. Thanks for the the replys.

[MikeB]

I just thought of this: Be prepared for potential issues with throttle rod, detent cable, and hard fuel line if you mount the carb too high. I once had that issue with a 1" spacer. However, the taller ones may work even better than the .320" Edelbrock that I mentioned above.

Carter had the right idea with the ThermoQuad that used a phenolic resin main body. And, of course, Holleys don't have the problem. I had an 82 C10 with a mild 350 that ran a basic 80457SA (Shiny Aluminum) 600cfm Holley that didn't even use a spacer, and it never had a fuel-boiling issue, even in hot Texas summers. Alert! This not a Edelbrock/Holley pi$$ing contest!

[72c20customcamper]

I’m thinking the 68 needs one truck runs great when it’s cool out but once it gets hot it has a slight flooding feeling at light throttle . Also the fear bumper gets a little soot on it . Doesn’t happen all the time just when it’s very warm out . I use Non ethanol high test in it too .

[Zonaman]

Originally Posted by MikeB

I just thought of this: Be prepared for potential issues with throttle rod, detent cable, and hard fuel line if you mount the carb too high. I once had that issue with a 1" spacer. However, the taller ones may work even better than the .320" Edelbrock that I mentioned above.

Carter had the right idea with the ThermoQuad that used a phenolic resin main body. And, of course, Holleys don't have the problem. I had an 82 C10 with a mild 350 that ran a basic 80457SA (Shiny Aluminum) 600cfm Holley that didn't even use a spacer, and it never had a fuel-boiling issue, even in hot Texas summers. Alert! This not a Edelbrock/Holley pi$$ing contest!

Roger that. I'm most concerned about my CV cable (700r4). I'm guessing I'll need to add 1/2 inch spacers to the bracket bolts to raise the cable and keep it level with soon to be 1/2 inch higher carb?

[body bolt]

If you have divorced choke keep that in mind.

[MikeB]

Originally Posted by Zonaman

Roger that. I'm most concerned about my CV cable (700r4). I'm guessing I'll need to add 1/2 inch spacers to the bracket bolts to raise the cable and keep it level with soon to be 1/2 inch higher carb?

That may not be necessary for a 1/2" carb spacer, but what you do need for an Edelbrock carb with GM OD transmission is this geometry corrector bracket from Sonnax.
https://www.sonnax.com/parts/2767-ca...-corrector-kit
They are also available for Holley carbs, and Holley clones.



Here's one that I used on a dual quad setup. Yes, throttle cable needs slight adjustment.

[j_cst_10]

A lot of times it is the fuel getting heated up in the fuel line. It is normally run close to the block. DEI offers some products for this.

I run an open 1" spacer with a Holley carb and would definitely go to a 4 hole set up next time to improve carb signal.

[MikeB]

Originally Posted by j_cst_10

A lot of times it is the fuel getting heated up in the fuel line. It is normally run close to the block. DEI offers some products for this.

I've heard that before. I have some DEI heat shroud that closes with Velcro, and I think it's a large enough diameter to fit over my lines and filter that sit 1"-2" above the manifold. Even with a spacer, I sometimes find myself cranking over the engine for too long.

[leftybass209]

Originally Posted by j_cst_10

A lot of times it is the fuel getting heated up in the fuel line. It is normally run close to the block. DEI offers some products for this.

The other issue that significantly contributes is not having a return line. A return line as close to the carb inlet as possible, will keep fresh, cooler fuel constantly circulating. Obviously adding a return line isn't the easiest option, though

[body bolt]

I went through this fuel boiling saga a couple of years ago. I ran cool water onto the fuel pump and the hard line to the original Quadrajet. No change but when I cooled the carburetor (I tried two) the rough idle settled down. I was intent on switching to Sniper but I tried a Holley 4360 I had laying around and the problem went away. Quadrajets don't seem to like that cast-iron skillet.

[Zonaman]

Originally Posted by j_cst_10

A lot of times it is the fuel getting heated up in the fuel line. It is normally run close to the block. DEI offers some products for this.

I run an open 1" spacer with a Holley carb and would definitely go to a 4 hole set up next time to improve carb signal.

I did manage to insulate the fuel line & filter from pump to carb with aluminum wrapped fiberglass. I haven't installed the spacer yet. The problem is fairly reproducible- Hot weather, hitch up the boat, no overdrive, hit the freeway, come to a stoplight after exiting- STUMBLE! STUMBLE!, recover. Maybe I'll make a run up to the lake and see if there's any improvement.