HTRDLNCN

I have a 4.75" ten rib top pulley and a 4.5" ten rib bottom pulley,
blower displaces 420ci
On a 540 tall deck I am guessing this would give me 5-6lbs of boost..
Am I in the ballpark here?

MILD THUNDER

iTrader: (3)

No sir. That's like 6% under drive .stock pulley combo on 800sc was 18% over. You need a larger bottom pulley . that combo you have might make 3psi at best I would think.

MILD THUNDER

iTrader: (3)

You prob wanna start somewhere around 10% over is my guess.

HTRDLNCN

the Holley chart for the blower shows 5" top and 5" (1 to 1)bottom giving 5-6lbs on a 540 tall deck..

Thats what I was using as a starting point..

Forgot about under/over driving.

My bottom pulley is the stock pulley from the SC800,,
top pulley have no idea,,..
Just cant find much aftermarket selection for the ten rib pulleys,,

HTRDLNCN

SC800 was a 577" though..
Thats why I thought I would still make 5lbs on the smaller 540..
Of course i was looking at the wrong numbers..

HTRDLNCN

Thanks for kicking my brain into gear,,
I was only looking at the sizes and not the position,
with a bigger top pulley its underdriven regardless the sizes,,
duhh!!
Feeling stupid now....

MILD THUNDER

iTrader: (3)

I am pretty sure the 800sc bottom pulley is larger than 4.5 inches. The 600SC bottom pulley measures 4.60 diameter. I am betting thats prob what you have. Stock 600sc top pulley, was 4.9 inches. Stock 600sc with that blower was a 502ci, made around 5-6lbs with that pulley combo. The 800sc may have used a 4.75" top pulley, but with a larger bottom to get the 18% overdrive, somewhere around 5.6" in diameter. . Sucks cuz not many pulley options with the merc 10 rib setup.

Black Baja

iTrader: (2)

OP you could try Innovators West they make custom pulleys

Biggus

iTrader: (1)

I've got a stack of old B&M pulleys that I'm planning on throwing on ebay numerous diameters. I'll see what I've got

HTRDLNCN

Thanks,,let me know..
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