Carburetor Base

[JimNolan]

Guys,
    Should be getting my engine back at the first of the week. Everything Balanced ready to assemble in 3 easy steps. Ha.  I've got a question about the carburetor that may sound silly to you guys but I need to know.
    I'm using the Streetmaster intake and I'm going to run the 670cfm 0-80670 Avenger Carb on it. The baseplate of the carb has these holes and milled out veins all over the bottom going from one bore to the other.
    Question:  Do I need to run a gasket and 4 hole spacer to go between the carb and intake so these holes and veins are utilized as if on an intake with a square bore carb base. Or, can I go ahead and just use the open 1" spacer and open gasket without worring about those holes and vein cutouts on the bottom of the baseplate of the carburetor.    I've never had an open type intake before and all the holes and veins on the bottom of the baseplate has me a little confused. I can see some of the purpose with the vein cutouts but the holes confuse me.

[jayb]

Those channels are there to make sure there is communication between the various vacuum areas of the carb, if you use a four hole intake manifold.  If you use an open plenum, they would not be required, but not all the carbs go on an open plenum manifold.  So the answer to your question is go ahead and use the open spacer; it won't make any difference to the carb.

[JimNolan]

Thanks Jay

[amdscooter]

Guys,
    Should be getting my engine back at the first of the week. Everything Balanced ready to assemble in 3 easy steps. Ha.  I've got a question about the carburetor that may sound silly to you guys but I need to know.
    I'm using the Streetmaster intake and I'm going to run the 670cfm 0-80670 Avenger Carb on it. The baseplate of the carb has these holes and milled out veins all over the bottom going from one bore to the other.
    Question:  Do I need to run a gasket and 4 hole spacer to go between the carb and intake so these holes and veins are utilized as if on an intake with a square bore carb base. Or, can I go ahead and just use the open 1" spacer and open gasket without worring about those holes and vein cutouts on the bottom of the baseplate of the carburetor.    I've never had an open type intake before and all the holes and veins on the bottom of the baseplate has me a little confused. I can see some of the purpose with the vein cutouts but the holes confuse me.

Great news your long block is coming home soon! Be sure to do a dry run with that 1" spacer. I planned on using one as well but with the new intake + the breather element I'm using the cumulative height was just a hair too tall to fit under the hood.   

[JimNolan]

Amdscooter,
    I emailed Holley and asked them the same thing that I asked Jay about the 1" spacer whether it should be open or 4 hole. This is what he wrote back. I gave him all the details about the engine. Jay had told me to go ahead and run it open and that some carburetors wasn't meant to be run like that so I thought I'd write in and ask.
Hi,
You can do this but I do not recomend the spacer unless you want to kill the bottom end power.
A 1" spacer will help the top end but will kill the bottom end, I would install it direct on the intake
Thanks Ricky

I hope Jay reads this, I'd be intersted in his viewpoint. Jim

[jayb]

Well, I guess I took your question to be whether you should run a four hole spacer or an open spacer, not no spacer.  There is something to be said for his comment, because an open spacer will bias the power curve towards the upper end in some cases.  But you see that more with a dual plane intake than you do with a single plane intake.  Since you have an open plenum on the Streetmaster intake anyway, the effect on the bottom end will be minimal, like a few horsepower or foot pounds of torque at most.  His comment that it will "kill" bottom end makes it sound like you will loose a bunch of power at lower engine speeds, and this is simply not true on most engines.  See pages 218-221 in my book for some practical data on this.

[JimNolan]

Jay,
   You're right, I was asking whether a 4 hole or an open 1" spacer because of the carb base. From what I'd read the 1" spacer makes for better atomization. I'll go back and read those pages in your book.
  The guy from Holley did make it sound the low end torque would be taken away and he never did completely answer my question about the Avenger Carb being a carb well suited for an open intake other than to say go ahead and bolt it on.
   I'm planning to use the spacer if I don't have hood problems. Thanks Jay