does it make a differance what kinda carb. spacer is used on 500 cfm edelbrock carb. with a offy inatake? not sure which one to use, the 4 hole or the open type. this would be a daily driver 230 L6. stock engine with HEI. also using stock exshast manifold. any advice would be great. ty.

The people who make the spacers say an open one may improve top end,a 4 hole may improve low speed response.They also say results may vary depending on the engine and state of tune.
My own experience on a 4 bbl 261 Chevy engine was a 4 hole spacer an inch thick messed up low speed performance.You really have to try them out for yourself.

I would just run the four hole setup so the air/fuel velocity stays higher than an open one.
You could also do some porting/blending the turn in the intake manifold under the carb adaptor plate.
Give it a nice big radius (qty.three)instead of a sharp 90 degree turn.
Hope that makes sense?

Hank

You need the 1/2" spacer to allow the throttle arm to clear the front manifold runner as you know. Hank told you right about the velocity. Run a 4 hole spacer and use a 4 hole gasket on each side of it. The Offy intake has a 4 hole adapter as part of it and the spacer and gaskets are a direct bolt on with no other work to align things. Keeping the 4 throttle holes separated will give you the sharpest throttle response and also make tuning the carb much easier for you.

after ready everyone's post, it all makes sense to me. so i went out to my local autozone too look for the spacer's, both 4 hole and open. and i came across several types of both styles. grabbed em' both that fit my application and when i saw another adapter in the back of the rack that said, 1" spacer for four-hole and open manifolds, fits holley,edelbrock,AFB,carter. this thing is sweet, it has 2 adapter plates that fit inside the spacer to make it either 4 hole or open. comes complete with gaskets, bolts, and all. the plates look like their made out of phenolic plastic kinda material. what u guy's think? let me know if u need a part number? thanks for all the help so far,,, keep ya posted on the progress. thanks

I'd recommend that you return the phenolic spacer and go with the simplest 4 hole aluminum one that will do the job. A big issue with these engines is whether or not to use heat under the carb and it has been debated a lot here so I won't drag it up again except to say the last thing you want on a street engine is a heat insulator - non metal spacer - under that carb. My 250 gets by fine year round with no carb heat of any kind but I do run an aluminum spacer and what bit of heat it transfers to the mixture I wouldn't want to lose.

You may end up having to run heat no matter what but the aluminum spacer will enhance that as well.

mike g, are u using a stock exshaust manifold or a after-market type? the spacer is alluminum on the exterior, the outter shell, and the inner phenolic. the four hole themself's is just plastic, the rest alluminum. here's the site,,. www.spectreperformance.com the part number is, #5764. check it out all. and let me know. if i should use it or not . thanks.

I run Clifford street rod headers on the 250. 2 separate 3 tube headers that have the collector flanges ending at about the oil pan flange of the block. There is no way to get direct heat contact to the intake with this set up so generally a water heated plate from Langdon's or someplace is used under the intake. I do not run any kind of heat under my intake, others have had to and others have not.

The adapter you are talking about is an alum body with a non metal insert which is argueably better than an all non metal adapter but I like things simple and inexpensive and would use a basic all alum 4 hole job from where ever you can find one.
You already seem to have the other kind and since you have a stock exhaust that bolts directly under the intake you might be ok as I have found over the years that the Edelbrock carbs when set up correctly are less dependent on the heat than the Holleys for our applications.