supermx96

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?

gofast540NY

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

FIXX

iTrader: (2)

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..

Griff

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.

supermx96

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

blue thunder

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.

MILD THUNDER

iTrader: (3)

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.

MILD THUNDER

iTrader: (3)

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

supermx96

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.

FIXX

iTrader: (2)

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..