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-   -   Blower with Carb questions (https://www.offshoreonly.com/forums/general-q/348275-blower-carb-questions.html)

mike tkach 07-10-2017 10:33 PM


Originally Posted by GPM (Post 4567653)
Just curious, and have no clue, would that motor ever see vacuum with a Roots style blower

the answer is yes.

mike tkach 07-10-2017 10:36 PM

was this 502 origionally a 502 mag,hp500 or?

MILD THUNDER 07-10-2017 11:47 PM

you sure its flooding out, and not leaning out? Does is sneeze/backfire thru the carbs?

I'd hold off on calling Nickerson. Best to do that when you get your tax refund in the spring. Youll need that, and a few months to get the carbs dialed in after he butchers them up.

adk61 07-11-2017 01:03 PM


Originally Posted by TruxtonFox (Post 4567583)
502 with 10-71 blower/intercooler twin 750 carbs on top. Jet size is 74/84 with 4.5 Power Valve. Set timing on stand, installed in boat and when in gear at 2800-3200 engines will flood out. PV is not boost referenced. 7 psi at the regulator. A1000's feeding aeronotive regulators....I'm no carb expert and am thinking my PV are set to low? Any help is appreciated

did you reset the floats when boat was in water? cause I'll bet if ya did it on level ground ya might have a couple high ones.. also are the cabs inline or sideways mounted?

getrdunn 07-11-2017 06:02 PM

You fouling plugs at that rpm? Also what plugs are you running?

i would take that tax refund though and put towards some larger boost referenced carbs. 10-71's with 750's? Just a thought. With the 088's you may not see a lot with lot of work or aftermarket replacement.

Im betting PV size.

SB 07-11-2017 06:28 PM

Nothing like having an OP disappear for a bit to answer some questions. :)

TruxtonFox 07-11-2017 08:11 PM

Sorry guys, wasn't getting any email alerts. For sure flooding out, set needle and seats with boat at rest in the water. 100% sure it's flooding, plugs are wet. As I accelerate to get onto plane and hold at 3k the boat runs there for 10secs or so, slowly lose rpm and then motor does. Blowers are obviously way to big for the 502's, my thought was the blower was pulling the pPV's open to soon and flooding it out.

TruxtonFox 07-11-2017 08:11 PM

Carbs are sideways mounted

TruxtonFox 07-11-2017 08:13 PM


Originally Posted by mike tkach (Post 4568021)
with non boost referenced carbs i use a 9.5 or 10.5 power valve.how far out are you idle mixture screws?

2 1/4 turns out, idles perfectly, will run up to 4000 with no load no issues, soon as you put load on it she floods

getrdunn 07-11-2017 09:33 PM

What 10-71's you have and how fresh are they? Just curious. I would have your carbs looked at and gone through by speed shop per your application. You decide to downsize to fresh tbs 8-71's let me know. Regardless what way your u go I'd definitely have a good trustworthy carb guy check your carbs out.


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