502 Performance Update

[Greg K]

After about 4.5 hours of break in time on my new motor. I decided to grab a handful of throttle and see what it was capable to do this past Tuesday. In 90 plus temps and flat water, the GPS in hand topped out at a solid 73.7 mph at 4800 rpm's with a King Cobra drive and 25" Turbo 1 prop. Held it there for a few seconds and then backed off, that felt good. I'm sure I can find another mile an hour or two still..
At the moment, my jetting is really rich and is blackening my transon every outing. I plan to drop a couple sizes on the jets and play with it some more. First oil change done and ready for the weekend.

[smoothie]

Way to go Greg,your no.s look great,prop slip is textbook wink it does feel good to be flying that fast :D

[Ranman]

Kickass!

[boldts]

Outstanding! Your right about the feeling running all out and the bow just floating on air. Add a little chop and I bet you find a tad more MPH. Best of all, steady and solid at 73 + :D

[Tomahawk]

Alright Greg. Now we're getting someplace. Congrats. Go a little easy on the leaning out. Prop seems to work real well as I would expect. Handling good as well?

[RickR]

Ape
You have a problem somewhere??? You shoule be close to 70 GPS.

Rev limiter?
Fuel restriction?

I would try a 20" Raker and see it the RPMs go over 4500.

[Greg K]

I have to ask first, which version King Cobra drive do you have? Flat top or one with a hump on top? The other thing is do you have tabs and what position are they in when you run it? How far are you trimmed out as well? Depending on what brand of tach you have, is it accurate? I know mine isn't on my dash and I use a digital tach clipped to the number one cylinder when I test.
When I had my 454 and spinning a 21" OMC Viper, I would be turning 5150 rpm with a speed of about 65. Went to a 23" Turbo then and went about the same speed, but with reduced revs.

[rag top man]

Say Greg, along the way in this thread, educate me, what is the difference betwen the drive with the hump, and the one without? Thought all King Cobra drives were the same.

[Greg K]

In 1990, the King cobra drive changed to the one with the hump to accomodate the cone clutch. Some 1990 model boats could have leftover 1989 non cone clutch uppers. The smaller engine drives were non-hump styles too, which you may see on some, but then were repowered later with larger engines.
In 1992, the lowers changed from the very large skeg to a smaller Volvo SX style you see today on those drives.
Leftovers and carryovers to the next model year was not uncommon to see on some drive packages.

[THE APE]

GREGG AND RICK, THANKS FOR YOUR INPUT. I!VE GOT THE HUMP TOP OR CONE STYLE.I KNOW THE OLDER STYLE HAD SERIOUS SHIFTING PROBLEMS.A PROPELLER SHOP IN DETROIT SHAVED DOWN ONE OF MY PROPS FOR SPEED> IT RAISED MY RPM!S ,NOT SPEED>.I!VE RUN WITH TABS SLIGHTLY DOWN OR UP WITH TILT UP ON THE OUTDRIVE. A SOMEWHAT UNEASY FEELING,LIKE GETTING NEAR YOUR MAKER. IF YOU CALL ME AT 517-548-0161 I!LL CALL YOU RIGHT BACK TO SAVE YOUR DIME.ON THE GAUGES TEAM MARINE IN WISCONSON MADE ME A CUSTOM BLACK DASH WITH GAFFRIG #1 GAUGES W/GPS SPEEDO.I!VE PUT SO MUCH MONEY IN UPGRADING MY WIFES GIVING ME THE EVIL EYE, BESIDES ITS HARD TO SLEEP WITH ONE EYE OPEN. THANKS AGAIN eek!