Why did'nt you tell us it was a B3 before ?

I have a bit of experience with a B# on a boat capable of 60 mph and I can assure you that the B3 props must be spotless at all times to attain max RPMs and speed. It may not be your problem right now , but keep them really clean at all times.
What is that old rule of thumb ... an eighth of an inch of growth on the bottom can rob you of 20% top speed ? ? Something like that .

Did you find out what the trouble was?

I had this but not any where near as bad. Did you do valve springs when you did the rebuild. Mine just laid down and went soft as butter. My guess is its a whole lot of problems. Dirty prop. Dirty bottom, Knock sensor wire, Dizzy cap corroded, plugs may died, maybe a lead under load goes soft, fuel filter or water in fuel and half a ton of unwanted water on board someware. Sorry to be negative but my experience says a bug loss will be easy to find or a lot of little things. Jason

Nope- haven't found the problem yet! Yanked the boat from the slip and just got it today after a hull and drive acid wash-- I'll be out Thanksgiving weekend (Ah, to live in Arizona--today was 84 degrees!) checking out how much speed a clean boat will pick up. When I pulled the drain plug only a quart or so of water drained, so no big water load. I gained 5 mph before cleaning the hull- it will run 40 now- don't know whether it's due to the new distributor cap or better altitude density( it has cooled off 10 degrees in the last month-- down from 90's to 80's), but we will see next weekend. Don't know whether they miked or tested the valve springs, but they supposedly freshened up the seats so hopefully the shop was sharp enough to check the springs. I still feel I may have a weak injector or two-- I guess you can't diagnose them without removal-- sucks the big one!!!

Have you been able to check the fuel pressure yet?

Fuel pressure was 40 lbs on a cheap Auto Zone guage at idle and seemed to be steady when I revved the engine, but I have not checked it at WOT yet (noone onboard with me at the time). I will do that this Friday. I did check the pressure with the vacume line disconnected. Per the manual the pressure should be 43 lbs, so how bad is 40-- would that make a major difference? I think WOT is the real test, I know....

UN-FRICKEN-BELIEVABLE!!!!!!!!! Splashed the boat on last Friday to see if an acid-washed bottom, drive, and props (it's a B3) would matter and-- low and behold-- ran 58.2 mph on GPS. Faster than it's ever been before!!! The gentleman who had experience with B3's at 60MPH was right-- they have to be clean and a little growth will knock you down almost 20% in speed. I had a bit of help-- ambient temperature about 75 degrees, 1/4 tank of fuel and just me and the wife onboard-- but I'm a happy camper-- no more diagnostics to do and now I can just do 'add' projects on it instead of 'fix' projects!!! Thanks to all you guys and your hard worn experience and advice.

Yep, I have 2 friends the bought identical boats, '04 Regal cruisers, 350's with B3's.

Friend 1 pulls his boat every month or so to clean the bottom. Friend #2 doesn't.....his boat was lucky to get on plain.

Well , it's nice to be on the money for once , especially around here

I have found that even with a perfectly clean bottom we get a condition out here in certain locations that on props ,it's kind of a precursor to the heavy growth , resembles grains of sand . YES grains of sand ! About 4-5 per square inch or less and at least 2 mph evaporates.

Runing on a nice cool, dry day makes a difference too .

Steve

what kills me, though-- is that I didn't have 1 inch long strands of algae or barnacles or something that extreme hanging off the hull and creating that kind of drag that would account for a loss of 18 mph and 1,000 rpm! I had some green slime-- I had pulled the boat from the slip in July and stopped at a carwash and cleaned off all the green-- but the calcium deposits (our lakes are very mineral laden here) were still on the hull, drive, and props-- but come September and October just a bit of slime had returned and caused such an exteme effect. I'm just a happy camper and amazed that such little visible build up can have such a dramatic effect.... This kinda cool stuff is what keeps boating so interesting!