speedtigger

iTrader: (16)

I needed a heat insulator for my carb to stop fuel bubbling and bowl overflow on the hot Florida days. So, the question became, which one. Four hole? Open? Divider style? After a bit of reading, it turns out that opinions and experiences vary. This just means one thing. Spacer test!

Here are the 3 test spacers. Predictions welcome!

buddha845

iTrader: (3)

got my money on lucky #8724 in for results because i love comparisons

topbrent

iTrader: (1)

Try a tapered spacer also.

stinkybutt

The open gets my bid too. Seen it on our dyno. You will see a gain in mph. We have milled the divider out of rpm intakes when a spacer won't fit under the hood. If the carb is too small it allows the cylinders to pull from both sides of the carb.Usually a dual-plane intake can use a bigger carb.
Aleck

xpndbl3

iTrader: (23)

gets my vote

ZONES89RS

iTrader: (25)

Tapered all day.

speedtigger

iTrader: (16)

Too tall. I only have a 1/2". Also, I bought all 3 of these spacers with hardware and gaskets for about half the price of one of those super suckers.

xpndbl3

iTrader: (23)

sure you don't have 1" ?

speedtigger

iTrader: (16)

Well, since you are offering it to me for $25, I guess I can try to make room for it.

stinkybutt

This spacer has shown 8 rwhp on some cars on our dyno. I'm going to try it on our car this week. Of course it would need trimming to fit over the plenum divider on the RPM manifold.
Aleck

ZONES89RS

iTrader: (25)

My 15 dollar spacer that i modded myself yielded 2 tenths at the track, looks like a super sucker, but was just a cheap plastic piece:

speedtigger

iTrader: (16)

I see die grinding in my future.....

speedtigger

iTrader: (16)

I put the dual plane divider spacer in today for driving around until I could do the test because I need some insulation for the carb. As you may have suspected, there was no seat of the pants difference, but I did notice the my WOT AFR leaned out about .3. I thought this was interesting.

gjestico

iTrader: (5)

Whats the theory behind how those HVH tapered spacers work ? is it the shaping of the airflow as it makes the 90deg turn under the carb or just gettting the carb higher off the manifold floor ?

ZONES89RS

iTrader: (25)

Smoother transition for the fuel entering the intake i assume.

3pedals

iTrader: (3)

I'm guessing the A/F being leaner means that the carb is "seeing" less signal, and flowing less fuel because of it. I take that as meaning there is less vacuum in the manifold at WOT, and I beleive that once jetting is corrected it will show more MPH through the traps because of it.

stinkybutt

The spacer gives more plenum volume, and like others have said less carb signal, so you need more jet. Same reason a Victor needs more jet and pump shot than an RPM.
I wish I had an RPM to do back/back dyno.
Aleck

stinkybutt

Zone, Did you try the spacer before the mods? Just wondering if the mods or the spacer helped more?

Aleck

MTC_75vette

http://4secondsflat.com/carburetor_spacers.htm

I am also interested in what spacer would give best gains. I have only 3/4 on an inch under my hood and came across this warhead cone spacer and may have to give it a go see if I see any gains.

ZONES89RS

iTrader: (25)

Yep, before was 7.3, after was 7.1.