Weiand 177 Blower Pulley Size
 

Hey All,
I have a boat with a 525 SC Motor and the dash gauge is showing its making 8 to 8.5 lbs of boost at WOT (5200 RPM). From what I understand this is higher than the stock boost. Trying to figure if I have a faulty gauge or an aftermarket pulley. What is the stock diameter of the pulley in a Weiand 177 blower in the 5252SC package. The one that is on now is 3.5 inches.
Thanks in advance
Eric

Ok

Hey all Please don't pass up on this thread because of this answer. Thanks Blue Thunder but it doesn't really answer my question. Just looking to find out what the stock set-up was. Griff??

Stock is 3.5" upper pulley and 7" lower pulley. Stock boost is 5.5#.
Is this something that just started???
A restriction like exhaust valves not opening all the way could cause a boost pressure increase. I would definately verify the gauge first before doing anything else.

If you have a 7" lower pulley, to make that much boost you would need a 2.85" upper pulley. A stock upper is (if my bad memory is correct) 3.25", which will make 5.5 psi. All boost numbers are assuming you don't have a chiller.

Im not sure if its something that just started happening Griff. I dont recall that much boost last fall but I only had it for a few runs. I did the top end rebuild this winter but used all stock size valves but did put in severe duty intake and Inconel exhaust. New Hydraulic lifers too. If it were and exhaust valve issue would the motor run strong like it is?

I just dynoed a Hawk 525 today with a 177 Blower and stock pullies. 4.55 LBS boost at 5500 RPM.....

What heads?

I get about 5psi with the 3.23 top pulley, and 7" drive pulley with my 454/177 combo.

GM iron heads. 088 castings.

Roller cams or flat tappet? Where did you get the small pulleys? I been wantin to try some. My bottom ends are all forged and rods, mains, and heads studded. I think i can handle the couple extra lbs with the aluminum heads too.

Flat tappet cam. Comp cams PN 11-564-4. I may sell my small pullies. Their new in the boxes.

I think I better check my boost gauge first. I dont start making any boost on the gauge until about 3500 RPM. Is this normal? Anyone have a good method for testing the gauge?
Thanks in Advance.

Thats pretty normal with a stock pulley. It should make a little boost when you start planing out and then the load decreases and boost pressure goes away.

What plugs should we use Griff?
What A/F should we shoot for at idle and cruise and wot?
Thanks!

AC MR41T or NGK equivalent
Never checked AFR's on my 525SC. Tuned it by looking at spark plugs and adjusting air bleeds for idle quality.

maybe someone redid the engine with higher than stock compression pistons/milled heads/etc ? the factory pistons are no longer available( I needed some a while back)

Old thread that Swamp brought back

ngk vee power 9 heat range. 11.8-12 wot and 13.5 idle af. Been doing it many yrs with 9.5:1 and 6lbs on 177s.