boost reference or not
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boost reference or not

  1. #1
    classic hot boater Orange Peel's Avatar
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    Default boost reference or not

    do i need this? I have talked to some people about this and have been told i can take the power valves out of my 750 DP's and do the same thing? i found some for good price and need to know what to do. the ones i found are 750s with boost ref and i have 750s without.

    Thanks Nate
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    Hondo Jet blown540's Avatar
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    You don't need boost referenced power valves unless your spinning your blower fast enough to create a vacuum under the carb. If this happens it will suck the PV shut and lean out your mix So if your planing on over driving like a madman you might want to consider converting your carbs or buying the other ones. I'm the paranoid type so I went with boost referencing even though I was told by many I probably wouldn't need it

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    Member paradigm shift's Avatar
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    Quote Originally Posted by blown540 View Post
    You don't need boost referenced power valves unless your spinning your blower fast enough to create a vacuum under the carb. If this happens it will suck the PV shut and lean out your mix So if your planing on over driving like a madman you might want to consider converting your carbs or buying the other ones. I'm the paranoid type so I went with boost referencing even though I was told by many I probably wouldn't need it
    You will get a lot of differing opinions if you do much searcing but I agree referencing is good unless you have them proffesional built then go with what they give you. I think in a larger heavier boat you are at more risk as you can run with a pretty good load at very low boost and still have high vacuum under the carbs keeping power valves closed when you need them most. When I ran a flat bottom with a blower it was hard to run very long in those conditions or WOT for very long. Plug em and tune accordingly or reference them just to make sure you do not have issues listed. JMHO.

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    Senior Member junkyard's Avatar
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    What dose it take to convert auto 1050 dom carbs to boost ref carbs.

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    Highaboosta Unchained's Avatar
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    Quote Originally Posted by paradigm shift View Post
    a pretty good load at very low boost and still have high vacuum under the carbs keeping power valves closed when you need them most.
    Boost and vacuum at the same time.....LOL......sooner or later someone always says that.

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    I think I could run more boost but it's a real hand full right now

  8. #6
    mo balls than $cents$ IMPATIENT 1's Avatar
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    you can tune the power valves and make them run just as good as a boost referenced, we've done dominators and 4150's that way nd had great luck. boost reference is just something else to go wrong, keep it simple.

    Dare to be different, if it turns out great you can claim you planned it that way.

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    If you take out the Power Valves, and put plugs in, increase your main jet 10 sizes to start. Then see if it is too lean/rich. I used to have a 1980 Turbo Monte Carlo(factory), and it had a special valve on the intake manifold to properly control the power enrichment circuit. You might want to check into that...

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    Quote Originally Posted by IMPATIENT 1 View Post
    you can tune the power valves and make them run just as good as a boost referenced, we've done dominators and 4150's that way nd had great luck. boost reference is just something else to go wrong, keep it simple.

    This man speaks the truth. I looked at doing it all types of different ways on my two 1050 dom's. I ended up letting Dean Nickerson set them up without boost referencing. Nickerson installed 8.5 pv in my doms. I was running 4.5 last year with big jets.

  11. #9
    mo balls than $cents$ IMPATIENT 1's Avatar
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    Quote Originally Posted by Big Cliff View Post
    This man speaks the truth. I looked at doing it all types of different ways on my two 1050 dom's. I ended up letting Dean Nickerson set them up without boost referencing. Nickerson installed 8.5 pv in my doms. I was running 4.5 last year with big jets.
    unchained(mark) taught me how to do it i just listen well we ended up about the same on the last 1050's we did, man it ran good and got great fuel useage compared to when we had them at stock settings.

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    Quote Originally Posted by IMPATIENT 1 View Post
    unchained(mark) taught me how to do it i just listen well we ended up about the same on the last 1050's we did, man it ran good and got great fuel useage compared to when we had them at stock settings.

    I'm hoping for better fuel useage in the 3000-3500 rpm range also. You guys use 20:20 linkage on them? Thats what I went to from 1:1.

  13. #11
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    Quote Originally Posted by Big Cliff View Post
    I'm hoping for better fuel useage in the 3000-3500 rpm range also. You guys use 20:20 linkage on them? Thats what I went to from 1:1.
    i think the doms were 1 to 1 , they were the older style 8896 doms that didn't have air bleeds. didn't take much time to get them set up, think we spent 45 minutes jacking with em till we got a sweet a/f reading and the vaccum gauge under the carbs looked happy during cruise.

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    From the Olds Jetfire, to the Corvair Corsa, turbo Capri, and the last carburated buick turbo, the OEMs all set up their carbs to be boost referenced. This does not include the Paxton blown T-Birds and their ilk, those had the carb enclosed inside a pressure box and didn't require any special power circuit, just different jets, emulsion tubes and hi-speed air bleeds. Anything less than boost reference IMHO is "getting away with it". Richening up the jets by some standard amount (say 10 sizes)and plugging the power valve hurts driveability,and the biggest issue is the power valve channel restrictions vary in size tremendously! To plug the power valves correctly (if that is a possibility), requires the area of the PVCR to be added to the area of the jet, and refigured to the proper new size jet area. When I bought my 14-71 blown 25 Daytona, the shop that did the carbs richened up the primary and secondary jets by the 10 size "old wives tale", and plugged all of the power valves. At 9-10 lbs boost it required C-16 fuel and 26 degrees of timing to keep out of detonation with the 3 circuit dominator 1050s. Fuel mileage was HORRIBLE at part throttle. I converted the carbs to 2 circuits, jetted them to 2 sizes richer than stock, reinstalled the power valves, boost referenced them, and now run pump gas at 12+ lbs. boost and 34 deg. timing. BTW the correct calculated rejetting for plugged power valves would be +16 sizes with these 1050s! The power valve channel restrictions are .078", thats equilivent to about a #81 jet by themselves x2, if I remember correctly. P.S. the top speed also increased by 6 MPH too. Of all the peeps that I have talked to about this, none had done a back to back test the same day on boost reference. Oh yeah, I called the shop that set up the motor and carbs and asked about the BSFC #s on this setup, they said that they did change the jets to peak the HP on the dyno, but these were their DYNO carbs(two circuit too!), not the carbs that were finally installed on the motor! A lot of peeps are making do with plugged power valve blower carbs, if you are happy with what you have, its fine with me. No offense intended. The carb/boat shop told me that the ten size deal worked on all Holleys with blowers. I guess he never bothered to look at PVCRs and note the different sizes. Everyone that is happy with their setup, leave it alone, I just offer an alternative for the experimenters among us. The car companies decided to have dedicated blower carbs, I wonder why. TIMINATOR
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    OOPS!!! I forgot to mention that i also modify the secondary tip-in point to allow more throttle opening on the primaries before secondary operation begins. This helps fuel mileage during cruise. On my rig, I can now run over 10 mph faster on the primarys alone. TIMINATOR
    MODESTY IS A CRUTCH FOR THE INCOMPETENT!

  16. #14
    Senior Member smitt19's Avatar
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    Default mid rich

    I will second timidator you can get away with jetting up on the big end, but the plug were so fat on my deal jets in the 104 106 range black soot in the exhaust but thats what it wanted up top, even when the carb shop set mine up he didn't want to do the boost ref. with a lot of other changes he made internally.but on the dyno we were burning up o2 senors because it was so fat in the mid's sent them back he switched made them boost ref and it worked much better, dominators are notorious for having poor low speed cruising anyway

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