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Old 03-03-2011, 08:10 AM
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Carb Spacer Discussion

I figured I'd start a thread discussing the different types of carb spacers out there. I currently run the 1in edelbrock Phenolic black plastic style with my Holley Commander 950 TBI setup. I was wondering what effects all the different styles have? Ive seen the open style, the 4 hole style, and the 4 hole tapered style. Are there pro's and cons to each? If I were basing price to match what might be best - it seems that 4 hole tapered costs the most.

Just wondering everyone's thoughts on this was.

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Old 03-04-2011, 10:31 PM
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The 4-hole is to preserve separation for a dual-plane application. I've had the gaskets cause my throttle plates to stick open (not good), so be careful. Open is typically for a single-plane. for certain applications it might even work better for a dual-plane, but you'll never be sure unless you have a perfect computer model of your motor (and no one does). Also, different heights tune the plenum differently by increasing the volume. I like the phenolic types because they shield the carb a bit better from heat. But it's limited... the bolts still get hot. Maybe those new plastic composite intakes for recent motors will find their way to the hot rod aftermarket?
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Old 03-05-2011, 08:11 AM
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Tapered

There's some very long threads on several forums regarding spacer performance, or lack there of. Seems open work better on the big end and holed work better on the low end, and tapered seem to work better then standard open or holed because of the vortex created under the carb? Like Leoman said, without empirical data to back up the difference, it would be hard to tell on the street. Most agreed benefit is shielding the carb from heat! That being said, I run a set of 2" tapered aluminum spacers on my FE with dual quads on a lo-raise intake. I put these on to get more clearance for an aftermarket distributor. Can't say there was a real seat of the pants difference, but sure looks cool!
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Old 03-05-2011, 10:16 AM
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Let me just say - I've never seen something so simple make a huge difference. I switched to a Wilson 4 hole tapered spacer. I was a little leary about dropping 125 on something so simple - but WOW. Everything I read says use open spacers on single plane intakes, and for dual planes, use a 4 hole or 4 hole tapered. But wow... This was truly glorious.

I got the motor up to temperature after doing the job - and was sitting at a light and decided - lets run a holley commander 950 data log and wack open the throttle. With no expectations as nothing I ever changed made an off idle difference - this thing starts shredding rubber from idle right to 6000. Thinking no way, maybe the ground was damp/wet/sandy/something - I get to the next light. Again and again consistent no hesitation tire shredding power. I was even from a few mph roll making a turn on to another block and said lets see what happens - normally this would REALLY hesitate with a slight roll out for some reason. Instant power as I stand on it and go down the block sideways - something only previously possibly in rain...

I did notice everything seems to be much leaner now, especially at WOT over 3500. So Ill need to retune - but man - its like a whole new car. Never did I expect something so small to make such a huge difference! Heck - when I first bought the spacer it was merely for clearance - I had no idea it was throwing off my tune.
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Old 03-05-2011, 11:08 AM
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I put a 2" open spacer under my Speed Demon and it really woke the motor up.
Cured the idle quality problems I had with the four holer.
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Old 03-05-2011, 12:21 PM
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Quote:
Originally Posted by 84Caprice57
Let me just say - I've never seen something so simple make a huge difference. I switched to a Wilson 4 hole tapered spacer. I was a little leary about dropping 125 on something so simple - but WOW. Everything I read says use open spacers on single plane intakes, and for dual planes, use a 4 hole or 4 hole tapered. But wow... This was truly glorious.
I read up on these and I'm ready to risk the $$ to try it, even at the expense of another inch of my precious air cleaner element height

Wilson does say that the one case where they don't help is with a high-overlap engine with reversion. I have a lot of overlap, no idea about reversion, but I'll give it a shot anyway. Wilson says try using a 'combo' spacer (or you could make one... essentially it's a 4-hole changing abruptly to a full-open) if reversion exists.
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Old 03-05-2011, 09:45 PM
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Ok, just to clarify... my innate frugality got the better of me. After more reading, I decided to try the el cheapo experiment first (well, it'll cost me $45 incl. shipping). I already have a 1/2" open phenol spacer, mostly for heat insulation. Wilson says a hi-overlap might like a combo spacer better. Since I effectively have the bottom half of a 1" combo already (I can't go much higher for hood clearance reasons) I ordered a 1/2" 4-hole phenol to sit on top. The idea is to see if I get clear off-idle and midrange improvement. The theory is that I will, but having gone through the old K&N plastic Holley hat to increase airflow, the K&N element that gives you 'more hp than no air cleaner at all' and a couple of other guaranteed quickies, I wanted some hint that it's gonna work first this time I have rotten vacuum and ought to be able to tell if my primaries are getting more signal pretty easily.
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Old 03-06-2011, 06:41 PM
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I bought my tapered spacers from Star Performance, nice guys, great price, not a polished finish, but neither is my FE!
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Old 03-08-2011, 03:52 AM
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Swapped on a pair of AFR165 on my 306 last summer and have had a hard time trying to tune the best out of the enegine. At the time I`m running a Edelbrock 1405 into a old type RPM intake using a 1" four-hole Mr.Gasket plastic spacer. (plastic fantastic)
After reading some stuff about spacers on Ford Muscle I was linked to this utube-video showing some guys diong a intake comparison++. Now I had no way but try this out myself so I decided to cut out the center of my four-in-one to make it into a half-open or 3/4 open type. And it definetly works on my combo. The most interesting part is how this pacer-opening makes the enegine stronger on lower revs. After swapping back to manuel gearing this winter I can`t no longer just fool myself by kicking it down to a lower gear so now I feel the enegines real powcurve much more than I used to. Fine thing, there`ll shure be some tuning this spring.

http://www.youtube.com/watch?v=i2DvnoHWagk
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Old 03-31-2011, 02:28 AM
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I'm using a rip off/copy 1" 4 hole tapered spacer found on EBay. I like it, alot. I originally used it on my big single plane and now I'm using it on my RPM air-gap copy intake, I spent some time with a carbide bit to smooth the transition from spacer to intake.









Since installing the intake with this spacer under my Mighty Demon 750 annular booster carb. With a more aggressive timing curve. My engine seriously woke up, it starts, idles and revs way better than it ever has in it's entire life.

A short vid of some revs since installing this intake & spacer.
http://www.youtube.com/watch?v=HHO1dZRMwwo

The engine is a roller cam 350, bored .040" over.
Flat top pistons, performance Vortec heads (185cc, 2.02"/1.6") 10.7:1 compression. Comp XR276HR10 roller cam

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Old 03-31-2011, 10:39 AM
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Quote:
Originally Posted by 84Caprice57
I figured I'd start a thread discussing the different types of carb spacers out there. I currently run the 1in edelbrock Phenolic black plastic style with my Holley Commander 950 TBI setup. I was wondering what effects all the different styles have? Ive seen the open style, the 4 hole style, and the 4 hole tapered style. Are there pro's and cons to each? If I were basing price to match what might be best - it seems that 4 hole tapered costs the most.

Just wondering everyone's thoughts on this was.
Too a large extent it's a tuning device, some engines respond to them some do not, some require extensive retuning to find anything.

If you get an immediate positive response it usually means there was a tuning problem which the extra plenum volume helped solve or hide.

Nothing against their use but expect a cut and try. I do think the cost of these things is outrageous. Most designs you see can be duplicated at home with a chunk of plastic or aluminum, a hole saw, electric drill, some files, a die grinder and cutters, and a saber saw for a lot less money and a little sweat equity. But then I come from a generation that had to make parts rather than buy them 'cause they weren't available to buy. So my money went into tools and machines to make parts.

Bogie
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Old 03-31-2011, 11:10 AM
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nice mykk.

can't figure out why your taper spacer has threaded mounting holes.
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Old 03-31-2011, 01:29 PM
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Ok, just to update my earlier comments on the thread.... I'm limited to a 1" spacer on my setup due to hood clearance. I'm running a low-profile Weiand single-plane on my 350, with an old Cam Dynamics 'super-3/4' cam with a lot of overlap.

I already had a 1/2" phenolic open spacer. I added a 1/2" 4-hole phenolic on top to basically fab a 'combo spacer' (which Wilson recommends for motors with a lot of overlap since they say the tapered variety might amplify reversion on such motors).

The results were quite good as far as throttle response and idle smoothness. I have yet to try anything really hairy as the roads here still have some salt on them, but preliminary tests have been very encouraging! My first test (in my driveway when the roads were still totally grubby) went like this: I backed out, pulled to the back of the driveway, put the th350 in D, took my foot off the brake and punched it about 3/4. I thought I had skidded in sand, but a look revealed two 4-foot patches on bare asphalt. I run 275/60R15s at 20psi in back, so the patches were pretty wide! Also, the tires are taller than normal and knock down the effective gear ratio from 3.73 to about 3.50, hardly holeshot material. I was quite pleased, especially since my little 350 isn't at all cammed for torque.

I did hit the throttle-binding problem My gasket has bigger holes than my spacer, so I dremeled out the top of the spacer just a tad, since the bind wasn't very strong (a tap of the gas pedal cured it). It's gone now, but I'm still not sure if I was binding or if I just had the carb torqued down too hard since I was paranoid of vacuum leaks with 2 spacers and 3 gaskets. I may have warped the baseplate a bit, but if so it has sprung back with my latest (and less torquey) installation.

Conclusion: I'm interested enough to pursue this further, that's for sure!
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Old 03-31-2011, 01:39 PM
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cool.

how did you measure hood clearance? play dough?
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Old 03-31-2011, 01:45 PM
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Quote:
Originally Posted by 001mustang
nice mykk.

can't figure out why your taper spacer has threaded mounting holes.
Thank you. I think it's just rough tooling marks by whatever bit was used to drill the carb stud holes. Like I said, cheap EBay spacer. But it works, and well.
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