Hot Rods Carb spacers with 4x2 manifold

I have an Offy 4x2 intake for a 348 I'm working on, and I'm wondering if carb spacers would have the same benefit here as they would with a single or dual 4bbl carbs. I use a 1" or so spacer almost compulsory for the normal motors I set up and have seen great improvements, but I haven't really messed with this type of intake before. I've even done some 1/2" spacers on tripower, but all of those intakes have some kind of plenum, and then at least some length of runner to the head. Thus log style intake has each carb right over the intake ports, and the plenum seems more like just a balance tube than anything, at least in my mind.

I'd like the looks of the carbs being taller since this is going in a roadster with no hood, but I also want to get the most I can and don't want to hurt performance too much.

Any thoughts or input is much appreciated!

 

thoughts and input
the spacers could help straighten out the charge,
they could help isolate the carburetors from engine heat,
they could help create more room for linkage,
they could essentially increase plenum volume and make the charge more consistent,
or you might not notice any real difference at all.

 

I’ve always installed phenolic spacers under any multi carb intakes. In the old days I had to make them. I like isolating the carb bases from the manifold. Normally none are over 1/2”. Good luck.

 

If you Google carb spacers, you’ll get some test results. But mostly single 4 barrels. I’ve seen a lot of 1/2” ones used on tri power when hood clearance is there, but mostly on 94’s or 97’s and probably for heat isolation.

There’s some test results here, but it’s Ted Eaton on a y block. Just because I remember reading it. But it’s a quick read, and maybe you can draw your own conclusions.

https://www.eatonbalancing.com/2012/09/29/carburetor-spacer-testing/

 

Last year I set up a 4x2 intake on a small block Chevy, in A 32 roadster. It ran and drove pretty good, but it was lacking on the bottom and a little bit. It was an offy manifold also, and I was told if I put some one inch spacers under the carbs. It would help this out, but I never did. And that customer has never complained. Also know a girl with the same setup in her hot rod and it runs just fine. Has Stromberg 97.

 

2" spacers....ran great on a souped up 283....

 

I don't think there is a down side. Getting a decent air flow for metering gets more complicated as you add more carbs. And various manifolds have differing balance tubes, or in some cases none. I usually use 1 1/2" aluminum spacers. I can see a benefit of a phenolic spacer in the mix as well. Here is a 6X2 that I have on the bench at the moment.

 

This looks good with the same material as the intake. So they kind of blend in

 

If the carburetor openings in the manifold are full open, or even half open (not a four hole), then take a few minutes to shape the "bottom" of the spacer to "fit" the manifold opening, similar to the spacer below.
In other words, "remove all FLAT areas on the bottom of the spacers.

I've been doing this for over 30 years...YES, it does help the fuel/air flow, even at lower engine speeds.
I just got done (bought two weeks ago) doing this to a 1/2" spacer for one of my engines.

Mike

 

Great way to eliminate that billet (yuck!) look is to bead or sand blast those to look like cast aluminum....

 

Thanks for all the replies! I've decided to go with a set of 2" ones, as those will do what I want them to do, and also help fill up the engine bay a but. Win-win in my book!