Any idea what the CFM rating is on that carb? My guess would be 625 .

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Just stainless flappers. And I'd agree a 750 might be too big. I think I have a rebuildable 650 dp around here.

No idea but my guess would be in the 600's.

How many hours are on this motor

xm 270 hr 300
ls6 spring's 70.00
APR studs 90.00
comp 787 retainer 70
air gap 250
750 eldo marine 300

A few links

http://www.carcraft.com/techarticles...pring_upgrade/

http://www.pacificp.com/forum/viewto...d21288c9eebedd

Wont be a speed demon but you might think you have a two stroke going on with that b3 huge midrange

Trash, It has 1.81R stamped on it.

Pliant it has less than 200 hrs. on the whole boat. Had 150 hrs on it when we bought it last spring. Yes it sat in a garage most of it's life, and still looks and feels new.

The fuel pump was filling the crankcase with gas after we had it about a month and I got lucky and caught it. Noticed it running rich (soot on the back of the boat) and the oil pressure dropping, so I put a new fuel pump on it and cut the filter apart and everything looks fine, and oil pressure is good. Other than that It's all original as far as I know. All the bolts still have paint on them. Going to take the impeller out and look at it before start of the season, and pull the outdrive and check alignment and lube it, since it probably has never been off.

Ok, 1.81 gears with 24" prop set. The theoretical max speed with that combo at 4500 rpm is 56.5 mph. Slip numbers tend to be a little lower with B3 drives and guessing around 7-10% (maybe less) you'd be in the 50-52 mph range.

To get to 60 mph you need to spin the motor in the vicinity of 5400 rpm with your current O/D ratio and prop set. Make sure you don't have a rev limiter in your way.

I ran edelbrock aluminum heads and a ZZ4 roller cam on my 245 chris craft, went from 41 mph to 53 mph overnight... weiand stealth intake 650 holley, thu hull exhaust, stock shortblockgreat CHEAP combo...

Wow, that makes me want to get out there with a "good" GPS and watch the tach much closer. I was over 4500 rpm, I just honestly don't know how much. Playing with the trim etc etc kept my focus away from the tach. I may also hook another tach to it on the hose and see how accurate my stock tach is.

With more power I would then either have the props worked over or change to a 26" prop set. I don't think I need to be spinning my stock cast-piston short block to 5400.

These are options I would explore after working on the engine. I can be buying parts through the summer and be ready to swap out parts next winter.

Max RPM at WOT on that motor should be 4,800 RPM. That means the rev limiter will be around 4,950.

When you do the impeller, just get the whole kit with the new housing. Those housings are notorious for cracking and leaking.

A friend I work with who's into performance boats mentioned that the plastic housings were prone to failure, but I'm pretty sure mine is metal. I have a spare from an older boat that I know is metal.