urban_cowboy

From my tuning and testing, a small phenolic gasket/spacer like Holley sells that are .25" thick are good for separating the carb from the hot intake manifold. This really helps in Texas where the summers are 100+ and under hood temps in traffic get very hot. That and a return line style pressure regulator virtually eliminated by fuel vapor issues.

A true carb spacer like a 2" or 3" can be very useful in a single plane type intake. A four hole style will give more throttle response and move your torque curve down by increasing the velocity of the air fuel mixture and aiding in atomization. An open style spacer will move the torque curve up but will hurt throttle response because it increases the plenum area.

Racers use them all the time and if you have the hood clearance are a great way to further fine tune your engine power band for your style and drive needs.

I am not sure why you would want one made from aluminum. That would limit the effect you get on the temperature barrier, so you would get some performance effect, but might still have fuel heat issues.

kalli

that's something I don't really understand either ... why alum for those. can only be useful if you have zero problems with vaporizing (hot carb) and just want to alter the plenum area. But if you're racing you shouldn't have that "get's-hot-in-traffic" problem either. so it's a product for racers only I guess.... same caliber as distributors with no vac advance ...

Gun Jam

They have some pretty fancy ones

http://www.summitracing.com/parts/WS...0/?image=large

http://www.summitracing.com/parts/WS...0/?image=large

Hummmm

-Gun

kalli

saw them. half the price of a carburetor ... where's the relation? isn't the carb you have spread bore?
couldn't just buy one for a spreadbore and taper it yourself. can't be much different thann porting and easier material as well

Gun Jam

I cant tell if they would work or not....the carter AFB 600 is the same thing as the edelbrocks 600 performer series...Not sure if those are spread bore...the butterflies are kind of the same size....the 2nds are a bit larger but not much

-Gun

nba1341

they have that one where you just mix and match them like a puzzle to create what you want

is that the one you guys are linking? I know that that one is pretty damn expensive though

2+2GT

I have a stone-stock 289HP with aluminum 1" spacer and no vacuum advance. Runs great, used to be my daily driver.

ozarks06

The spacer does two things: it isolates intake manifold heat from the carb, resulting in a slightly cooler mixture and eliminating the fuel boiling issues mentioned (particularly if it is phenolic), and it increases plenum volume. The advantage of a cooler mixture is obvious, but just insulating the carb from the engine heat probably wouldn't make that much difference. Newer cars either use plastic intakes or thicker gaskets to insulate the whole intake manifold from the engine heat (as in the 4.6 DOHC motors), and of course, they keep the hot coolant out of the intake. The increased plenum volume probably helps with trottle response and low-end torque.

Keeping the fuel from boiling and vapor locking is great in hot locations. But it can have a side effect. When I was a young lad (in the 1970s) I put a Holley 4bbl on a 2bbl intake with a Mr. Gasket adapter. The adapter was aluminum but it didn't transfer enough heat to the carb. When it was cold, usually right around freezing, the carb would build up ice in the venturies (from condensation) and it would run rich, like the choke was on full. I had to keep my foot on the pedal at stoplights to keep it running. Fuel injected engines don't have this problem since they adjust the mixture on the fly (which is why they can use plastic intakes).

JDraper

I run a .320" thick carb spacer on our 289 primarily for heat insulation. I can't go much higher with the stock hood because my air filter will hit it...

Here's the one we're using: http://www.summitracing.com/parts/EDL-9266/
I've got a Holley Street Avenger perched on top of it.

4reboy

I took the carb spacer that was on my engine off and haven't had any problems. However I switched to an aluminum edelbrock performer intake so maybe that helps with heat, and I also have one of the "fattier" carb gaskets, probably .25 - .33" thick so that may help as well. However, even when I used to have the thin gasket I never noticed any problems. The benefits of a carb spacer might be more noticeable on a more radical engine than what mine has though.