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Wanted: Main Jets

Discussion in 'Technical Q&A' started by hanknum, Apr 24, 2005.

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  1. hanknum

    hanknum Formula 3

    Nov 1, 2003
    2,050
    Santa Barbara
    Full Name:
    Henry
    #1 hanknum, Apr 24, 2005
    I thought I'd try here before I ordered some main jets from Pierce. I'm looking for 135's. This is since I've "freed up" the intake on my 308. Please let me know if you aren't using them and would like to sell.

    Thanks

    Henry
    [email protected]
     
  2. thecarreaper

    thecarreaper F1 World Champ
    Silver Subscribed

    Sep 30, 2003
    18,120
    Savannah
    #2 thecarreaper, Apr 24, 2005
    Henry, its been mine and other experience to NOT goto the 135's with the open air cleaners. the car runs dead rich, to the point the rings may get washed out in street driving. i would go with a cooler NGKBP6ES, instead of the hotter NGKBP5ES and change the air correctors from 200's to 190's.

    my friend JFRAZAR has been doing ALOT of work on his carb GTS and he is going back to bp7es plugs and stock carb jetting. his car was running way too rich with the 135's and the indv. filter set up. his car ran a bit warmer than mine also, but that may have been the gauges reading funny. check out Russ Turners threads, he and BIRDMAN have some great info posted on this. i purchased new bp6es plugs and i am planning on changing the air correctors in my 77 gtb also.
     
  3. hanknum

    hanknum Formula 3

    Nov 1, 2003
    2,050
    Santa Barbara
    Full Name:
    Henry
    #3 hanknum, Apr 26, 2005
    Hi Mike,

    I thought it was pretty standard to increase the main jets especially after reducing the intake restrictions and assuming the engines run a little lean from the factory. Russ, Spasso, Dave, do you guys have any recommendations? I'll do some searching.

    Henry
     
  4. Doug

    Doug Formula 3

    Nov 13, 2003
    1,473
    Louisville KY
    Full Name:
    Doug
    #4 Doug, Apr 26, 2005
    I think I have some 135's that I pulled out of my car last year. Let me know if you are interested and I can take a look for them.
    Doug
     
  5. thecarreaper

    thecarreaper F1 World Champ
    Silver Subscribed

    Sep 30, 2003
    18,120
    Savannah
    #5 thecarreaper, Apr 26, 2005

    we thought so too. the 135's made my 78gts run too rich as well as Joe's 79gts. my GTB runs too well to mess with!
     
  6. Spasso

    Spasso F1 World Champ

    Feb 16, 2003
    14,656
    The fabulous PNW
    Full Name:
    Han Solo
    #6 Spasso, Apr 26, 2005
    My 308 had 125 mains/200 air correction jets with the stock restrictive airbox and the stock tall velocity stacks. The airfuel ratio was 14.5:1. A bit too lean according to knowledgable sources.

    This year with the opened up airbox, short velocity stacks and 140 mains/200 air correction jets the airfuel ratio was 12.3:1. A bit too rich according to the dyno guy at Carb Connection.

    At Russ's advice I went to 135 mains and 190 air correction jets. I am still in the process of going to dyno with this set up but we figure the A/F ratio should be around 13.2 +/-.3

    I have been told that the stock main jets for an early carbed 308 was 130's.

    I can't see where 135's would be way rich unless other factors come in to play, high float level, high fuel pressure, different emulsion tubes.?

    When I was running 135's with 200 air correction jets it felt like it was leaning out at the top end hence the change to 190 A/C jets.
     
  7. Dave

    Dave F1 Rookie

    Apr 15, 2001
    2,722
    Little Rock
    Full Name:
    David Jones
    #7 Dave, Apr 27, 2005
    Hi Henry,
    Of course I'm by know means an expert when it comes to carbs...
    But I run 140's on the mains in my 77 with K&N and Tubi and it's just right.
    Your 78 has a little less cam than my 77, so I would think 135's would be a good match.
     

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