I'm planning on a new hood anyways so this is very likely in the future if somebody can tell me what they do exactly. I've heard that they give you better gas milage, I've also heard that they give you more low end.
I'm using TBI and right now I have a 1" adaptor/spacer plate on a square bore edelbrock RPM vortec intake. This is on a 330hp flat tap cam engine. The Holley is ~670cfm and I'm curious about getting another spacer. I need an extra vacuum fitting and a lot of the spacers I'm looking at have a boss. They are also really cheap.
So what are they suposed to do?

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, Jon (350 TBI!)
91 Red My website

 

Carb spacers are tuning aids. Using either a 4 hole or an open spacer will give different results depending on the engine. Spacer thickness does the same. The only way to really know what works best is to try different ones. There was an article in a car mag last fall on carb spacers. I'll see if I can dig it up later.

 

open spacer give HP 4 hole give more torque. the main thing to me is the keep heat away from the carb or tbi. only thing to watch for is clearance with the hood.

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ICON Motorsports

1st & 3rd
MM Black Diamond 538 F&AM

 

Please dig up the article, I'd really like to hear what it has to say. Ede, I have a holley adaptor plate where the 2" 2 barrel TB sits forward on the plate (because butterfly's direct air to the rear of the engine). Would a 4 hole still make more torqueor is that only for a 4 barrel carb (thats what I'm thinking). And if the larger spacer makes more power, why don't I see more people using them. About hood clearance, I plan on getting a new hood anyways.

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, Jon (350 TBI!)
91 Red My website

 

I've read that if you use spacers, it's a touchy subject. The right height can help, but the wrong one will hinder. Trial and error is the only way to find out. It all revolves around cam, intake, heads, etc.

But you are right about a 4 hole not working on a TBI. An open spacer MIGHT work. Usually the intake companies set their's up so you don't have to use one, as long as u use the right intake for your setup. Your spacer is neccesary for the adapter part, right? Well there isn't anyway to get rid of it unless you go with a carb or TBI intake. I think the main reason a 4 hole is used is so that guys with a single plane intake can run a little better on the street. Like ede said, they give you more low end torque. If you have a dual plane, an open spacer might help a little in upper RPMs, but hinders what happens down low. Kinda defeats the purpose of a dual plane intake. That's pretty much what they said on HorsePowerTV too.

 

hey jon 350 tbi,

I'm here to save the day (you were kind enough to reply to some of my posts), I have the mag in front of me right now. Car Craft March 2001. pages 42-45.

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late model 91 rs
fully loaded t-tops
red leather
paint- gm red and yellow blend (light red)
custom pink rims
305 tbi k&n,computer chip
MTX sub and amp (very loud)
vic_v8@yahoo.com

 

I have the article too. They compared open spacers, ones with one divider in it, and ones with 4 holes, one for each barrel(obviously). Some that looked like they wouldnt help at all, actually helped alot. I think the biggest gain was like either 10 or 15 hp, with a very minimal gain in torque, but some lost like 5lbs while raising the hp level. Like stephen said, its a tuning aid, im sure diff. ones are better for each application

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• 83 Z28--ttops, 200k miles--very ragged out. sold, thank goodness
• 74 Z28--slightly modded 383, TH400 tranny, not too quick but fun to drive

 

When I dynoed my motor, I made pulls without a spacer, with a 4 hole and with an open. On my combination, it made no difference. I do run a 4 hole though just to keep the carb cooler.


Miles

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88 427 Camaro
12.18 @ 113mph 1.75 60ft
Currently installing 3.73's into my 9 bolt (YES,it is a 9 bolt & YES they are 3.73's, not 3.70. 4.11's to follow soon )
www.koolmeister.com

 

Okay, so I guess it's nothing but a tuning aid and even then very minimal. I would think it would help with torque down low since in theory you're adding length to the runners. I guess it's just best to isolate the heat if anything.

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, Jon (350 TBI!)
91 Red My website

 

And so you learn a valuable lesson Grasshopper! Next you will come to understand the technique of Jacking it up like a Mother...

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-