I need to know if the stock 525sc gen 6 carb (dom 1050) are already boost reference? I dont know how to determine if it is or not boost reference.

Also what is the right procedure to determine if you have the right PV on a boat engine?

I may be wrong but i thought boost reference only matters in a "blow through" application......

if it were boost referanced it would have a vacume port on it for a vacume hose that would go to the intake..

also see if it has 3 air bleade jets per ventury or 2 air bleeder jets..

Not boost referenced and I don't feel its needed for them. They run like an efi when properly adjusted.

The stock 6.5PV's work just fine in them. I had a bigger roller cam and was running almost 8# of boost and it idled and ran perfect.

That is for an upgrade 525sc with aluminum and b&m 250 blower and now i am in tuning of that engine and dont know if it need to have a boost reference carb. What is the right way to test if you have the right power valve?

I will take some A/f ratio # this week end see if i am ok

If you have a boost/vacuum gage on the dash, note what vacuum you run a cruise speed the select a PV.5-1 in less in vacuum. I run 5-5-5in vacuum at cruise so I run a 4.5in pv.

I also validate with my A/F meter to ensure it is not getting too lean before it opens. Thats the best way to do it.

That works ONLY if its boost referenced. The standard 525SC merc is not. Like griff said 6.5PV.

If you wanna be safe, you can put a 8.5pv. Only way to really check is either have a vaccum gauge under carb, but on top of blower. This is where the PV gets its signal from.

Boost reference the fuel psi regulator in a blow thru app.

I have the vaccum gauge that i can plug under the carb (on top of the blower) do you chek vaccum in drive at idle to determine the pv ?
What calculation +or- of the vaccum # ?

Thanks.

most boost gauges have a vacume part on the oposite side of the gauge..just install one in your dash to keep a eye on boost pressure..killl 2 birds with one stone..also make sure you have plenty of fuel pressure..at leaste 7 psi..