Your donations help keep this valuable resource free and growing. Thank you.
|
Carb spacer... |
Post Reply | Page 12> |
Author | |
GreggR
AMC Addicted Joined: Aug/21/2009 Location: Painesville, OH Status: Offline Points: 1267 |
Post Options
Thanks(0)
Posted: Mar/26/2013 at 2:32pm |
I notice that carb spacers are available as both 4-hole (or 2-hole for a 2V) and open designs.
Anyone have a preference? Is there a technical advantage either way? Did a search, but didn't find this question addressed... Thanks
|
|
No matter where you go, there you are... Buckaroo Banzai.'75 Hornet Hatchback
|
|
whizkidder
Supporter of TheAMCForum Joined: Mar/03/2008 Location: North Georgia Status: Offline Points: 2972 |
Post Options
Thanks(0)
|
I'm no expert, but I'd match the spacer to the manifold.
|
|
Ron Frost
marne1ancient @ gmail.com 910 nine two two 0563 "There is no limit to what a man can do, so long as he does not care a straw who gets credit for it. Charles Montague |
|
nda racer
AMC Addicted Joined: Nov/28/2009 Location: Ohio Status: Offline Points: 2591 |
Post Options
Thanks(0)
|
It depends on what your combo prefers.
A 4hole can crutch the bottom end on a single plane manifold and a open can hep the top end on a dual plane, etc, etc.
I put the low rise Weiand Excellerator manifold (it was brand new and $40) on a smog mill with 2.56 gears and ran 15.2, bought a plenum devider kit for it and dropped to 14.6. Nice crutch for a bad combo.
A buddy bought a Holley System Max kit for his car and it ran best with the carb directly on the manifold, cause the kit was set up perfect from tha manufacturer. He tried a few diffent spacers and went slower. 11.2s out of a stock bore and stroke 350 N/A not too bad for a dual plane manifold.
|
|
6768rogues
AMC Addicted Joined: Jul/03/2007 Location: United States Status: Offline Points: 6237 |
Post Options
Thanks(0)
|
That is what I do. |
|
Content intended for mature audiences. If you experience nausea or diarrhea, stop reading and seek medical attention.
Located usually near Rochester, NY and sometimes central FL. |
|
tsanchez
AMC Addicted Joined: Jul/09/2007 Location: Arizona Status: Offline Points: 4303 |
Post Options
Thanks(0)
|
Like NDA says, it depends on the engine, signal at carb and manifold entry. Most of what a spacer does is add plenum volume. I have had many time that it caused driveability issues, especially with air valve secondary carbs.
|
|
Red20
AMC Addicted Joined: Jan/29/2013 Location: Oceanside CA Status: Offline Points: 1556 |
Post Options
Thanks(0)
|
I use a 1", 4 hole spacer on a dual plane edelbrock performer intake on a 360 with an edelbrock 650 carb w/ mech secondaries. I noticed an increase in torque myself. No numbers to back it up, but my seat-o-the-pants dyno confirms it. One thing i did was chamfer the edges of the holes on the bottom side of the phenolic insert to help with air flow and reduce de-atomization of the fuel air mixture. I used a router and 1/8" roundover bit to do that. Don't know how much it helps, but I can't see it hurting.
|
|
WCKAMX390
AMC Apprentice Joined: Dec/21/2012 Location: Fresno Status: Offline Points: 44 |
Post Options
Thanks(0)
|
Used 1" spacer on my 390 ci, 4 spd AMX. Noticed a little better top end. Can't prove it, but felt it. Had to take spacer off because hood would not close and did not want to run hoodless...
|
|
1970AMX, 390ci, 4spd, RamAir, 3.54posi
2002WS6TransAm, ls-1, 6spd, T-tops, 22,000mi, ALLfactorystock 2012DodgeChallenger"Yellow Jacket"SRT8, 6spd, 392Hemi, 1of1000made, 1st owner2receive YJ in Calif |
|
jarcher401
AMC Apprentice Joined: Mar/11/2012 Location: pa Status: Offline Points: 79 |
Post Options
Thanks(0)
|
No lie, but on the engine dyno I gained 10hp and 11tq from adding a 1 inch spacer.
600cfm carb 8.5:1 Shorty Headers Gasket matched heads performer intake lunati 64501 cam
|
|
FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
Post Options
Thanks(0)
|
Every carb I've ever seen was designed to have a gasket seal over all of the underside except the throttle bores themselves. Alot of the hollowed out spaces under a carb are designed to derive their vacuum from ports carved into the throttle bores, and not just from an open space. Plus, the rough underside of the carb will create extreme turbulance under the throttle plates and around the idle discharge ports. Most stock intake manifolds have a closed plenum with individual intake bores, though they do eventually combine or have cross-drilled passages between them. I am always very careful to make sure the spacer matched both the diameter of the intake manifold bores and the carburetor throttle bores to provide a streamlined path of entry. It's worked very well for me.
When faced with an open plenum, I would still install a closed spacer while matching the spacer bores to the throttle bores only.
Watch out on 327's with factory Holley 4bbls. They have two extra secondary idle discharge ports with their own holes drilled in the manifold and spacer.
Any spacer increases plenum volume, and has all the effects on engine performance that a larger plenum poses. Where I live, fuel percolation is the carb is paramount, so I tend to pile on at leat 3/4" of spacers. More than that and the cab is just being heated by convection.
The primary way a carburetor cools itself is by the intake air flowing through it. If your carb ever gets really hot while driving, downshifting and reving it up to increase airflow helps. That is also why I believe in cold air intakes when the weather is above 85 degrees. Not for power, but for drivability. I've seen carbs get so hot, the accelerator pump shot vaporizes before it leaves the discharge nozzles. ....Arizona problems.
Edited by FSJunkie - Apr/14/2013 at 11:25am |
|
1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
|
Mr. Ed
Supporter of TheAMCForum Joined: Nov/12/2010 Location: Sewell, NJ Status: Offline Points: 4916 |
Post Options
Thanks(0)
|
I thought the spacer was primarily to insulate the carb from the heat of the manifold. Yes, no?
Thanks! Mr. Ed |
|
2014 Jeep Grand Cherokee Laredo "Gwendolyn."
1978 Concord Sport coupe "Mr. Black". 1982 Concord wagon. The Admiral. FOR SALE! 1976 Sportabout X, 304, auto, air. The Bronze Goddess |
|
Post Reply | Page 12> |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |