I have bit the Bullet!

79nautique wrote: maybe a shade higher on the rear float?

I adjusted the rear floats several times as high as they would go untill fuel poured out into the secondaries then back down. Same problem...boat seems to run strong and lose a little then it pop's thru the carb which is a lean condition.


I went ahead and installed a Barry Brant Demon 650 Marine Carb with electric choke and vacum secondary. Unbeleivable! This carb is an animal. I have a slight hesitation off the line I need to fix but the throttle response is amazing and crisp at all speeds. You now have to be careful if you hit the gas even half throttle or it will throw passengers off the seat if they are not hanging on. The fuel bowls are dual feed and also about twice the size of the Holley so it would be hard to run out of fuel. With all the good benefits of this carb I picked up more RPM and a little speed but still slower than before.

I spoke to Cam Research, Acme Props, and Boat Dr. and everyone agrees that this head/cam package was built for torque. I am now so far beyond the torque range as well as this prop being too small that it just can't pull the boat thru the water. Acme is sending me a much larger prop originally designed for a 1.5 to 1 transmission that they feel should bring the RPM's down to closer to peak torque and horsepower. Somewhere in the 13.5 by 17 size three blade. Acme states that if I have the proper torque to turn this prop my low end will pick up as well as top speed. If I don't have enough torque the low end may be a little flat. I feel I am almost there. I will report back as to the results. One thing is for sure, if anyone is planning on changing out to these types of heads and cam package it looks as though you have to have all of the other related components in sync or it is not going to perform properly as the engine is now radically different than before. Cam, rockers, lifters, push rods, heads, springs, intake, carb, ignition, exhaust, and prop must all be changed to work together or it will not perform to full maximum efficiency. I think the heads made the biggest difference on this package. They are moving so much more air now that it really changed alot.

I am not sure if the Barry Grant 650 would work well on a stock or mildly modified engine but I can't say enough about the increased performance of this carb. It literally feels like an entirely different boat now and just rips when you hit the gas.

Thanks!