Ill look into the ign. Thanks.

Bought a 69 camaro that previous owner SWORE was a 350 engine, when it died, found it was a box stock 307, with good heads, intake, carb, and headers. Still ran like a 307 however. I don't believe ANYTHING unless close family tells me and even then I have my doubts.

Isn't the merc 540 - 575 horse motor a solid lifter motor?

Kris Vogt

Ive had a head off of it. Its got a 4.5 bore x 4.250 stroke.



Bore: 4.5
Stroke: 4.25
Head Gasket: .039
Compression Ratio: 8.6
Cubic Inch 540.644625

I think you are trying to pull too much prop. I have a 21' 4" Baja Hammer with a 610 HP 540. I pull a labbed 28 Bravo 1 to 5,300 @ 86 on the GPS. I pulled a labbed 26 to 5,600 to 84. You have more boat than I do and a little less HP so I don't think a 28 is th right prop on that boat.

So far i have tried a 26 4blade bravo 1 and a 28 bravo 1. Turned them both the same exact rpm and speed. Tried a 32 labbed 4 blade bravo 1 and lost 400rpm, but mantained about the same speed. 32 obviously too big, but 28 prop comes out of the hole like a rocket. The only other prop i have is a 24 3 blade. Im going to try it tomoroow just to verify that im not currently over propped. It would be hard to believe the way it comes out of the hole with the 28. Im only 200-400 rpm shy for what my motor is rated for. Im thinking ignition next. If that doesnt do it, ill go with a new cam a springs... Sunsation aggressor is a fast hull. I saw 66mph gps with a 310hp 454 at 4800rpm 24 3 blade...

.......
 

I have no idea if this could affect anything, but it has a standard deck intake on a tall deck with spacers..

6272990 heads

the rev limiter is set for 4700 on the 310hp....

Ok. Then my tach is off or i remembering wrong. Lets try this again........ I saw 66 on gps with a 310hp.