Setup For Weiand 177 On 454
 

I've got a weiand 177 on a 454 mag in an 88 Formula 242ls. Motor is fresh and just broken in 4 bolt main forged internals 7.75:1 compression inconnel vales in steel heads with blower and carb off an old 525sc. Carb is a 1050 dominator. Boat only runs 62 mph gps with a 25p mirage plus prop at 30 degrees timing and 4800 rpm and 5lbs of boost. . It seems to run very rich the exhaust is getting the swim platform dirty everytime I take it out. I ran it before with a 23p mirage plus and it would turn too high 5500 at ~7lbs of boost but ran ~65 mph. I want to keep a safe tune most importantly but what can I do to increase speed and how fast should it run? More boost more timing? Thanks

my 454sc
 

88 scarab 30ft. twin 454, mercruiser weiand 177, 6lb. boost,
9.0 to 1 or 9.5 to 1 compression? 850 holley, 29p prop.
27degrees timing, 62mph gps at 3800rpm, rev limiter set at 4700rpm.
Runs a little rich at idle not bad.

dyno 2500rpm 603tq 305hp
dyno 4500rpm 540tq 460hp

hp still climbing at 4500rpm (cam lift .573?)
That makes me feel bad for the bravo1s.
Rev limiter for reentry.

I ran 8.75:1 @ as far as 35
32 is safe.
merc is known for over carbing this set up, so idle speed is real fat = fuel on platform
Wouldn't go crazy with the boost. These mini blowers work hard & make a lot of heat already.

What is your estimated power high 400s?

What cam?????

Whats your A/F looking like?

Stock 525SC timing is 35* which comes in gradually up to about 4500rpms.
Stock CR is 7.5:1
Stock boost is 5.5#. Running 7# of boost is no problem with a 525SC. I did almost 8# for years.
Stock carb jets are 98's all around.
You should prop it to spin 5200 rpms.

With the right cam, you can make 550hp reliable hp.

Cam is the #90767 b&m blower cam but there was no rpm listed on the cam card. I have no way to check a/f mixture. 98 jets in carb. So should I be safe with 7lbs of boost and 32 degrees timing? I have a 3" pulley I can try instead of the 3.5 I'm currently running. The loweer pulley is 7"

What are the actual cam specs???
Stock 525SC cam is 228/236, .530/.551, 114 lob sep.

I should be plenty safe with 7# and 34* of timing on 92-93 octane fuel.

236/246 .553/.571 114 are the cam specs turn it 5200 rpm?

With that much cam, prop it to spin 5200-5400 at WOT.

Thanks for the help!

my 454sc
 

Lunati cam 02006
specs
valve lift .553 .571 (1.7 rocker ratio)
lobe lift .325 .336
adv dur .283 .293
dur @ .050 .236 .246
center line 112* 116*
lobe sep. 114*
rpm range 2700-6700

850 holly jet size 87 & 90

4 years running no top end damage keeping it below 4800rpm.
Went through port motor this year #4 main bearing bad, one lobe on cam .030" wear (flat tappet) valve spring was binding 600+lb. to compress.
Less rpm longer it will last. More rpm more mph. I run 2800-3500rpm all day (ICW).

I run 102 jets all around in my doms on 177s w/4.5pvs. Only very light soot on the transom and it is all the way to the bottom of the transom so I know it is at wot where I don't mind it. 98s gave me a/f readings 11.8-11.9 in summer so I think you are good there. You may be over rich in the idle circuit. Is the transom only sooty to the water line?

I'm curious what you get for wot speed? We have same boat and similar power it appears.

You are wasting a lot of potential HP by only running 4800rpms with that cam. You may be saving the springs a little bit, but everything else has to work harder. That cam is designed to make its power at higher rpms on a 454. You would make more torque and HP with the smaller stock 525SC cam at 4800rpms.

My soot is on top of the platform so it must be at idle

Its takes some tweaking of the 4 corner air bleeds screws to get the idle set just right.
Set it up to idle at about 850rpms in neutral.
You have to do it on a completely warmed up engine.

Check your float level, fuel pressure,power valve.

I pulled the supercharger off to change the pulley and change the oil and noticed fuel in the oil. I just put new bearings and seals in it but never marked the rotor postion (to one another) on the gears. Do I just put them directly horizontal and vertical to each other? The gears can only go on the rotors one way and I see marks on the gears but if you line them up the rotors would hit. Thanks

http://www.holley.com/data/TechServi...ech%20Info.pdf

weiand sc tech info web page

tech # 270-781-9741

Dialing in a blower motor
 

Figure out a way to determine your A/F ratio. Should be 14:1 at idle, 13:1 midrange and 11.8to 12.0 wide open. The only way to determine this is with a meter. Everything else is guesswork. Good Luck.

Exactly correct as long as you are not too close to the edge of detonation with the engine build/boost.

You have to line up the marks. The gears are mitered so the rotor will hit until you get the gears seated to one another. Fine tuning of rotor timing is done with shims under the miter gears. Make sure those go back just like they came out or you will need to retime the blower.