SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: yzrider7 on June 20, 2019, 06:37:27 PM

Title: BBC rpm fix
Post by: yzrider7 on June 20, 2019, 06:37:27 PM
Hello, so from what I’ve been reading my boat is supposed to rev at least to 4600 rpm. I have a 1992 carrera eclipse 20.5 with a 454 bbc with about 136 hours total. I do not know if it’s been rebuilt or freshened up as I just purchased it. Motor runs solid and feels and sounds strong. Has a MSD ignition and a whole bunch of little goodies. I have an American turbine pump built by Tom Papp. I’m not sure what impeller is in it. When I go out I can only get about 4K rpm out of it at 56 mph. What should I start doing or looking for to get it to perform at what it’s supposed to? What should I check? Thanks in advance for the help.


Sent from my iPhone using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Title: Re: BBC rpm fix
Post by: MillerKiller510 on June 21, 2019, 06:16:47 AM
Is this the guy that I towed back with a jet ski over the last weekend

Sent from my SM-G975U using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)

Title: Re: BBC rpm fix
Post by: mash on it on June 21, 2019, 09:52:41 AM
Couple of questions-

56 mph, it that on gps?

What carb is that? Does it have vacuum secondaries? Are they working?

Where is the timing set? Initial should be a minimum of 10 degrees, up to 14 or so. (Also depending on the degrees of mechanical advance)

How fresh is the gas?

Is the tach accurate?

It sounds like the boat is running pretty well, and the tach might just be reading incorrectly, if boat speed is accurate.

That's all I got for now.

Dan'l
Title: Re: BBC rpm fix
Post by: yzrider7 on June 21, 2019, 03:14:46 PM
Couple of questions-

56 mph, it that on gps?

What carb is that? Does it have vacuum secondaries? Are they working?

Where is the timing set? Initial should be a minimum of 10 degrees, up to 14 or so. (Also depending on the degrees of mechanical advance)

How fresh is the gas?

Is the tach accurate?

It sounds like the boat is running pretty well, and the tach might just be reading incorrectly, if boat speed is accurate.

That's all I got for now.

Dan'l
It’s has a Holley 750 with manual secondaries. 56 was on gps. I drained the tank completely, put fresh gas and a can of sea foam in each tank before I took it out for the first time. I will check timing. The guy I bought the boat from said he had it at 65 on gps, he could of been yanking my chain.


Sent from my iPhone using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Title: Re: BBC rpm fix
Post by: yzrider7 on June 21, 2019, 04:02:00 PM
Is this the guy that I towed back with a jet ski over the last weekend

Sent from my SM-G975U using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Absolutely haha


Sent from my iPhone using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Title: Re: BBC rpm fix
Post by: MillerKiller510 on June 22, 2019, 02:41:05 PM
Check the inside of your pump and see if ya got some lake weed in there

Sent from my SM-G975U using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)

Title: Re: BBC rpm fix
Post by: 96Laveycraft21Xt on June 01, 2020, 09:27:50 PM
Tach is definantly off at that speed! 
SMFPacks CMS 1.0.3 © 2026