Purpose of Carb Spacer

5796 Views 9 Replies 4 Participants Last post by camachinist, Mar 20, 2001

basketcase

Discussion Starter · Mar 19, 2001

What is the purpose of a carb spacer? I recently purchased an Edelbrock performer intake and I have the Edelbrock 1406 on order. Do I need to install a spacer like the one on my 2v but specifically for the 4v? Also will I need to change the throttle linkage from the stock setup to compensate for the new carb?
Thanks in advance,
Dave

Dave
Reading PA
66 Signal Flare Red Vert
302 2V, 15X7 Cragar SS's with 205/60s

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camachinist

· #2 · Mar 19, 2001

On stockers, usually it serves to act as an attachment point for the PCV hose and adds a little more plenum space which helps with low-end torque...

If you decide to get one for your 4V, likely the throttle linkage won't need anything..it hasn't on my race car or D-coder and I have phenolic spacers on both...

BTW, get a phenolic spacer vs the aluminum one....the phenolic one insulates the carb from manifold heat better....

You can see one in action on my race car...note the wooden-looking thing under the carb....also note the throttle linkage and return spring arrangement...

I believe you can get one from Summit for about 30 bucks...

Pat
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Huskinhano

· #3 · Mar 19, 2001

I'm running the stock carb (4V) spacer on my Edlebrock 1406 just to make things easier. I'm also running a stock factory 4V manifold for the time being.

As far as the throttle goes, I cut the end off and threaded it with a 10/24 die and used a spherical end I bought from Mc Master Carr hardware book.

Getting back the spacer, I'd be curious too if there are any problems with this. BTW the spacer was for the pcv hose.

Tom
You can do anything you want to......ONCE!
aka "my 66 coupe"
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basketcase

Discussion Starter · #4 · Mar 19, 2001

I was looking in the Jegs catalog and saw they have the phenolic spacers for $23. What is the difference between the open, divided and four hole spacers other than appearance? Also, the spacers I did see did not have a tube on the end to accept the pcv hose. Is there actually an opening there where you install a fitting yourself or is it closed? Will the car operate properly if the pcv is not connected?
Sorry for so many ?
Thanks again, Dave

Dave
Reading PA
66 Signal Flare Red Vert
302 2V, 15X7 Cragar SS's with 205/60s

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camachinist

· #5 · Mar 19, 2001

I always use 4 holers....the last time I used an open was on an old Edelbrock Torker on the race car when I was using a plenum divider plate mounted in it...
Mostly the difference is torque characteristics due to the perceived plenum volume and flow distribution...

HUH?

As a rule of thumb, use a 4 hole with dual plane manifolds and an open with single plane manifolds....

PCV...you can install a fitting at the back of the spacer by carefully drilling a hole from the rear middle which intersects both back bores (just drill until the bit starts to break through) and tap the spacer for an appropriate sized pipe thread for a nipple which works with your PCV hose, most likely 1/4" or 3/8" NPT...I'm guessing you're getting the 1" tall spacer...
It is also possible to just drill the hole and epoxy a nipple into the spacer...use a good quality, high temp epoxy like HVAC repair putty...I prefer threads but hey, I've got tons o' taps laying around *G*

I'd run PCV in a street engine....things get pretty stinky otherwise and engine performance can suffer depending on how well the rings seal...

Pat
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· #6 · Mar 19, 2001

hope you don't mind if i get in on this....

what are the drawbacks to not having a spacer? i have a holley 600cfm on an edlebrock 2121....

65 pony from ground up, inline 6 (son's car),
66 Red Convertible, 289(dad's car)

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camachinist

· #7 · Mar 19, 2001

FWIW, I put the spacer on my D-coder mainly because I went to the aluminum Cobra manifold from the stock cast iron unit...aluminum conducts heat more quickly than cast iron so I figured I'd insulate the carb a little from that heat with a poor conductor, like phenolic...
The cooler the fuel (and air...another story), the denser the charge entering the cylinder...
Secondarily, it made an easy place to hook the PCV.....

On a street car, IME, the performance gains from a spacer are minimal....say .05-.10 on a 15 second car.

Drawbacks...hmm...not really any I can think of other than maybe an increased possibilty of vapor locking on extremely hot days...
If you can hook your PCV hose to the throttle plate of the carb, you really don't need a spacer...

Pat
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BillScott

· #8 · Mar 19, 2001

I got my only "D" in thermodynamics but here is my opinion. The spacer will provide a colder , denser (more energy) mixture to the carb. Either "HOT ROD" or some other TV show had a good explanation on the show a couple months ago - you might want to check their website. They described different hole patterns and thicknesses to change torque at high/low ends and other things. one thing i can't figure out is why my heater hose goes thru my spacer which heats up fuel mixture and defeats cool explanation - it probably prevents carb icing.

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· #9 · Mar 19, 2001

thanks for the lessons folks!

appreciate you a ton!

randy

65 pony from ground up, inline 6 (son's car),
66 Red Convertible, 289(dad's car)

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camachinist

· #10 · Mar 20, 2001

The heater hose runs there likely for the same reason there is a tube running down from the air cleaner to the exhaust manifold with a temperature-actuated air damper control.....
When the engine is cold, fuel tends to condense out of the air mass and gather on the cold intake manifold and cylinder head walls...kinka throwing the air/fuel ratio to heck...
Heating the air, whether by exhaust or water, helps keep the fuel in suspension and deliver it to the cylinders....Ideally, the hose running through the spacer should have a temperature controlled valve to limit or block flow when the engine reaches operating temp...

Engines are quite a balancing act, yes? *G*

Pat
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