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  1. #1
    Join Date
    Aug 2004
    Location
    Iowa
    Posts
    137

    1" Carb spacer or not?

    Just wanting to get some imput from anybody with carb. smarts. I've got a 388 sbc Eagle rotating assembly, 6" rods, solid cam, 544 lift with 256 duration, 108 LCC. Dart 200 angleplug heads, 9.6 compression. Victor jr. with a 650 Mighty Demon. Would a 1" spacer help my engine combo on the street and on the track? It runs really strong on the street right now, dosn't load up too bad just puttin around town, and is very responsive when given the chance. Thanks. Trond...



  2. #2
    Join Date
    Jun 2006
    Location
    Katy,TX
    Posts
    1,672
    Each individual motor likes a different spacer or no spacer. My RAIV 400 Pontiac motor with a 73 SD Qjet, 72 HO intake picked up 8 hp with a 1/2" 4 hole. Friend true 72 HO motor with same carb model, same intake different heads, cam and CI lost HP with it! Just got to try them.

  3. #3
    Join Date
    Aug 2001
    Location
    Connecticut
    Posts
    1,569
    Country Flag: United States
    You should gain with a 1" spacer-- I personally love HVH and Wilson's tapered spacers, they transition from the 4 round holes to the open plenumn and make a legit 10-12hp on a hot motor.
    1968 Camaro RS/SS, LS7 with Katech mods, T56 Magnum, C6Z06 Brakes
    1968 Camaro RS Convertible project LS3/480hp/4L70E
    1962 Corvette 327-340hp stock
    1972 Corvette LT1 Stock
    2006 Corvette Z06
    2011 Corvette GS convertible


  4. #4
    Join Date
    Jun 2006
    Location
    Katy,TX
    Posts
    1,672
    What spacers mainly do is lenght the intake tract to try and hit the different pluse waves as they go back down to help ram the charge into the shamber past the valve as it opens. Each different motor likes a different spacer height and shape.

  5. #5
    Join Date
    Oct 2006
    Location
    Ottawa, Ontario, Canada
    Posts
    154
    I think you need a bigger carb for sure.....that little 650 is definetly not enough for a solid cammed' 388" motor which should rev to ~6700rpm with that cam i'd say

    -Carm
    '69 Firebird Twin Turbo SBC 400" Blow-through

    9.80 @ 141 w/ 1.88 60-ft..... on 17's
    9.21 @ 153 w/ 1.45 60-ft..... on PUMP GAS
    8.60 @ 164 w/ 1.46 60-ft..... on RACE GAS

  6. #6
    Join Date
    Aug 2004
    Location
    Iowa
    Posts
    137
    Thanks guys for some good info. Carm, I called Demon and spoke with a tech and gave him all the parts in my motor. Based on that info he told me the 650 Mighty Demon would do me good on the street, where I'm mainly driving it. He also said those flow "wet" at something like 732 cfm. Interesting I thought. I have run it to 7000 no problem and it gets there without hesitation. Any more good information is always good! Thanks again guys. Trond

  7. #7
    Join Date
    Jun 2006
    Location
    Katy,TX
    Posts
    1,672
    They will tell you their 850 really flows 1000 cfm too! They use a different test pressure just like Holley does for their HP series compared to the old standard test for carbs, I'd bet a real 750 woudl pick you up also. to compare different series of Demons or Holleys look at venturi size and throttle blade size, bigger annular boosters also drop cfm a little also.

  8. #8
    Join Date
    Feb 2007
    Posts
    164
    Ok what is this wet flow some carb companies are using nowdays. Since when is an 850 now a 1000cfm carb.