You don't have the hood clearance to put much of a spacer!
The "theory" is...an open spacer "might" give more top end power (prolly single digit)
                           a four hole spacer "might" give more bottom end power.
Might......is a word a lot of hot rod tuners use when using spacers.

Open spacers provide a larger plenum under the carb so more vaporized fuel is available for the cylinders.
4 hole spacers provide a smoother transition for the vaporized fuel to be sucked   (EZ Don!!)    into each cylinder.
Mainly.........either one acts like more of a heat insulator than anything.
These Funnel-webs and super-sucker spacers kinda help a stock or restrictive intake to make a little more power.
Edelbrock RPM! is more like an old fashion/tried-and-true "high-rise" intake.
A taller OPEN plenum spacer on top of a 180 degree style intake ....WILL net you hood interference...butt-eye doubt any noticeable boost in scoot.......
6sal6

So you can cut a hole in your hood and add velocity stacks! 😜😂

The real world effects on power are typically pretty minimal due to what you can actually fit under the hood.  You'll see dyno tests all the time where they picked up 10HP, etc., but they had to use a 2" spacer to do it while still running a full height air cleaner, creating a combination that wouldn't fit under the hood of a truck. 

The insulating ability of phenolic is definiteyl worthwhile to keep the gas in the bowls from boiling, especialy in hotter climates and with ethanol laced fuel. 

Last edited by TKOPerformance (5/06/2022 12:36 PM)

I made and used one from epoxy impregnated marine grade ply wood under a 4100 on the 289 I used to run.
Worked great as an insulator.

Your car looked great back then as well Steve.