BBF can't make RPM's

[byrona]

I have a 1983 21' Eliminator daycruiser that I just bought. I took it out to the lake this last week and had a chance to really open it up and the boat would not go past 4000 or 4100 rpm's. The ingine is a 460 ford with a Holley 750 double pumper and log exhaust. Can anyone help eplain what is happening?

[Floored]

I'll go out on a limb and say large boat at high altitude. I don't know the impeller size or hp of engine but do a plug color check, make sure advance is working standard tune up stuff. even down here you would probably be 45-4800 rpm, so thats my guess. Maybe someone from your area, on the board,can help you out

[Jet City]

I would say your down on power (you knew that), if it was me I'd start with a compression check, then a good tune-up. Check timing with an adjustable timing light for initial and more importantly full advance. Your distributor will be a Prestolite if it is the original unit, I had to get mine recurved to achieve 34 degrees (all in by 3000 rpm) full advance, I also installed a Pertronix ignitor (electric ignition module), but points will work as well when gapped properly. The above plus new plug wires and coil along with some carb jetting took me from 4400 rpm to 4900 rpm. In good tune you may only see 4500-4600 due to living in the mile high state (less air, less HP), if the boat came from sea-level you may need to drop your mainjets around 3 sizes to compensate for elevation (1 jet size per 2000 feet), but get it tuned and check the plugs first (IMO).

[Squirtcha?]

That might be all you're gonna get with a pretty much stock motor and logs. It's probably running a AA impeller.
I'd think, check the tuning like Jet City Rebel suggested, there might be a little more there. That's a pretty big boat you're trying to push around. I've always heard that Daytonas run good but they also like a lot of horsepower.
If it's a stock BBF then the hp n tq is probably pretty much all in (300-330 hp or so) by 4000 rpm. They weren't really known to be high revving motors in stock trim.
Put up a picture if you get the chance. Always liked the Daytonas.

[Jet City]

Engine HP and impellor cut are the only factors in WOT RPM acheived. The hull size, weight and effiency has no bearing on WOT RPM, only the MPH. If I've pointed out the obvious, I oppologize. I too have a penchant for Daytona's.

[Doug H.]

Here's one from the chevy guys :D i have a 21ft openbow commander, 454, 330hp with logs berk (E) pump with rideplate and hyd div.. my boat tops out at 50mph at 41-42 hundred RPM by no means am i going to enter any contest (heavy boat) but the stock motor is giving me all she has and i accept that for what it is, tune ups are frequent with oil changes and good compression (125) im happy with the way it rides and cruises. here is what i will do for a little gain and MPH, fresh said of heads and a good camshaft plus intake and carb, this should put me in the 50-53 or 53-55 i will be happy plus use less gas cause now i have workable power without mashing the pedal, oh! get my pump reworked too, this will help i hope, all this is miner work and cost effective. :)

[Elk Chaser]

Only had my boat for a month or so and I have the exact same engine, exact same carb (changed from 600 to 750), exact same pump (aa impeller I think), exact same RPM, exact same length boat (Sleekcraft)
IMHO You're getting close to what you can out of her, but all these guys are right on the money as far checking the obvious stuff. After doing all those things and more I did not experience much more performance as it was set up fairly good to begin with but she did run cleaner and smoother. Altitude change is a big factor on any engine without electronics to make adjustments automatically, I would start with that, you are more than likely running fat if it was a low altitude boat. Don't expect much of a change after doing these things as they are not going to increase your horses by much more than a very small percentage.
I for one am replacing my logs with thru transom headers (coated rewarders), upgrading my ignition (MSD), and installing a loader on the intake (Super Sport). Least expensive mods that I could put together (about $1500) to increase my overall performance and horse power, some day aluminum heads will be in the making as well but that will be after a full lower end rebuild in a couple of years or so, if she makes it that long.
Just my 2 cents worth on the subject....

[Squirtcha?]

Jet City Rebel:
Engine HP and impellor cut are the only factors in WOT RPM acheived. The hull size, weight and effiency has no bearing on WOT RPM, only the MPH. If I've pointed out the obvious, I oppologize. I too have a penchant for Daytona's. Not a problem Jet City. I probably should've phrased it a little differently. It was supposed to be just a side note.
[ August 23, 2003, 07:20 AM: Message edited by: Squirtcha? ]