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Tuning a Holly 350?

Discussion in '60-Series Wagons' started by snorider, Jul 31, 2005.

  1. snorider

    snorider

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    Hello,

    I just swapped out the gas guzzling/squirting/dripping holley 500cfm carb on my 87 fj60's 2F for a spanking new 350cfm list 7448 Holley. I'm just getting started with tuning the carb using plug reading, I searched for Holley tuning and came up with a starting point ( this board is the :censor:) but does any one know the power valve size, jet sizes, and throttle cam color/ size that they've had the best luck with. Also, is the the .097 off-road needle and seat the correct spring loaded needle and seat for this application. Ohh and were roughly should the timing be for this combo? Thanks for the help.

    :cheers:
     
  2. dd113

    dd113

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    I use the stock jets. The PV is a 125-85 which I think is the type that will not blow out under backfire. Just make sure you get that no blowing out type! The needle and seat sound correct. I use the white cam on my 40 but experment with your 60 to fund the best shot pattern for you. Get a pressure regulator.

    Tuning a Holley invloves bones and a grass skirt. It takes a while but once you get it you will never go back.
     
  3. snorider

    snorider

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    Cool I'll pick up a range of pump cams and try out that power valve and n&s. Whats the deal with pressure regulators-sources? psi? While I'm at it I'm going to order up the side hung float and bowl. It seems there is a vented and a non-vented type is one better than the other for offroading? I think baffles were recomended as well? any opinions on which is the best type? :cheers:
     
  4. toyman317

    toyman317

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    I have a holley on my fj60 and have been having problems with hesitation at acceleration. Does that indicate my acc. pump is bad or do I need some kind of different pump configuration. I am not sure what model carb I have as it came with the truck. Has headers if that makes a difference.
     
  5. dd113

    dd113

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    NO idea on the vented VS. non vented. I always use the one that comes with the carb. Baffles do work well as do jet extensions. Here is the bones and grass skirt portion of this:
    The baffles keep the fuel from sloshing around and the jet extensions allow the it to pick up fuel at extreme downward angles. I use 1 extension on 1 jet and about 1/2 the baffle. You will need to play with which jet you extend. If you use 2 extensions then you will not get gas at upward angles. Too much baffle and you can suck all the available gas quicker than the pump can replace it.

    The acc pump has an adjustment between the cam and the pump. There needs to be an air gap in there; about twice what Holley specs. Set that gap them use you choices in cams to get the gas shot correct. The accelerator pumps come in different shot sizes. I use the smaller of the sizes.

    Another big issue is the vent tube on top. This needs to be extended as high as possible or gas will run out of it at extreme angles. Downey sells a part to do this or just pound some copper tube in the hole.

    The clear sight plugs are 100% needed. You want the gas just below the holes.
    Buy reuseable metering block gaskets and float bowl gaskets.

    NAPA/Holley etc.. all sell pressure regulators. I run around 2.5lbs of pressure and it seems to do well.
     
  6. snorider

    snorider

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    David,

    Thanks a million this thread'll hopefully save me 4.5yrs of tuning and countless $$$ in :beer: I've got all the goodies on the way except the baffles I guess I'm still unclear about what the devil they are. I see a baffle in the holley catalog that looks like a piece of bent tin for 1.97$ (couldn't work ; too cheap) and then there is the Downey (as in which way my bank balance is headed :doh: ) "sealed baffle kit" which they described on the phone as "made for the center hung float" and consisting of a piece of open cell foam, a gasket, and some glue for...... 50$ :censor: ?! Is there a way to do an end around on downy and make my own?? or should I just reach for my wallet and ankles simultaneously?

    :cheers:
     
  7. dd113

    dd113

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    Everything Downey sells is available elsewhere for less. Go to http://store.summitracing.com/ and look for HLY-26-89 they call this a baffle and I think it would work. I use open cel foam sorta wedged down into the bottom of the float bowl but this baffle looks cool.

    Also look for HLY-55009HOL jet extensions. I have used these and only use one as I mentioned above.

    Remember buy reuseable metering block gaskets and float bowl gaskets.
     
  8. poldo

    poldo

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    Useful thread.. I am in the same situation but I am trying to fix a 4412 500cfm
    I was wondering if I can partially convert the 500 cfm to a 350 by replacing the fuel pump from 50cc to 30cc and needles to limit the spilling and overflow
     
  9. toyman317

    toyman317

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    Thanks David for the info about the acc pump. I downloaded a manual for my 7448 and hope to try to get this thing to work for me but the manual doesn't talk about the pump. There is a fairly nice gap between the cam and the pump on mine...so much so that the cam wiggles around quite a bit. Next I will check the pump size but I am pretty sure it is what ever it came with stock. Are the pump sizes marked on the pump somewhere?

    I am also having another problem as well. When I decellerate, there is a pop, pop, pop through the exhaust. It is not a backfire, just a pop. Not sure if this is a vacuum problem or the carb. It is desmogged so there are much fewer vacuum lines than stock. The float level seems to be where it should be...no gas comes out when I open the window. Does this sound like the main jets need to be changed. If so which direction...leaner or richer? I will check the plugs and see what they look like.
     
  10. poldo

    poldo

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    I finished to rebuild my holley 500cfm the kit will fit both the 350 and 500cfm includes a 30cc pump and a 50cc one you can tell the difference by the size the 50cc is much bigger
     
    Last edited: Sep 1, 2005
  11. toyman317

    toyman317

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    I found that I had a vacuum leak which caused the hesitation. An exhaust leak is causing the popping. I think my carb is working pretty well except for not having the manual choke mechanism. Does anyone have an extra one laying around they don't need?