RPM at WOT?

D

Devveon

Cadet
Joined
Sep 29, 2012
Messages
8
I was looking at a formulat 29 PC, from 1989, we only did a quick run with it but it did not really get up to any good RPMs (2500 at most).
Does anyone know how what RPM I should expect at WOT?

This boat had 2x 350Magnums and Alpha drives
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: RPM at WOT?

Something really wrong, you should be seeing wide open throttle rpms of 4200 to 4600 on those engines if it has flat lifters in it, 44 to 4800 if roller. And no, props aren't the problem, so don't let them tell you it is.
 
D

Devveon

Cadet
Joined
Sep 29, 2012
Messages
8
Re: RPM at WOT?

Thanks Don,

They have had the carbs rebuilt, so they said that they needed to be adjusted. I will go back later and try it when they have adjusted them.
I would have expected closer to 5K RPM. But how do I know what type of lifters it got?
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,546
Re: RPM at WOT?

if your only getting 2500, I would go back into the carbs and not believe anyone that they only need to be adjusted.

also start with a compression test, check the timing, and the rest of the fuel system per the list.
 
emoney

emoney

Commander
Joined
Jul 19, 2010
Messages
2,551
Re: RPM at WOT?

Plus 1 on the compression test. Seems like you'd have noticed a "carb issue" on the way up to 2500 rpm. As for which lifters it won't matter until you get to around 4500 so it's kind mute at this point. Not sure what the price range is on this boat, but spending a few hundred dollars on a mechanical inspection is worth it's weight in gold. There's no such thing as "wasted money", meaning, "I wasted money on an inspection because I didn't buy it". It would be a LOT better to spending a few $$ now instead of a several thousand dollar mistake.
 
S

Solittle

Fleet Admiral
Joined
Apr 28, 2002
Messages
7,518
Re: RPM at WOT?

We probably have a couple of hundre posts here where the seller said "the only thing it needs is for the #$%^ to be adjusted." - - - And then the problems begin for the buyer. Remember the sellers goal is to get your money from your pocket to his. Have you mechanic or surveyor verify everything.
 
04fxdwgi

04fxdwgi

Senior Chief Petty Officer
Joined
Jun 10, 2011
Messages
754
Re: RPM at WOT?

Devveon said:
Thanks Don,

They have had the carbs rebuilt, so they said that they needed to be adjusted. I will go back later and try it when they have adjusted them.
I would have expected closer to 5K RPM. But how do I know what type of lifters it got?
Click to expand...

Did you actually try to do a full power run and "BOTH" engines only got to 2500 RPM? Seems a tad odd that both engines are messed up exactly the same..... I can see one only hitting 2500, but both? Have the drives been changed and if so, what is the ratio on them? Have the props been changed and if so, what size, pitch are they.

There has to be something common to the 2 to make them messed up exactly the same..( new throttle control and not set up correctly).. Just my thoughts....
 
dingbat

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
15,500
Re: RPM at WOT?

What kind of speed are you getting out of them? Could be a tach issue
 
jestor68

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Re: RPM at WOT?

All the OP said is that we made a short run, and only took it to 2500 rpm. He never said that it wouldn't go faster. He just asked what sort of rpm to expect at WOT.

Not much of a sea trial. Sounds like they just chugged around the marina for a few minutes. :facepalm:
 
D

Devveon

Cadet
Joined
Sep 29, 2012
Messages
8
Re: RPM at WOT?

It was not much of a sea trial, at that time we did not get out on the lake even, but gave it a good trial.
Anyway, was out today again. They claimed that they had just replaced the sparks and it now ran great.
It defiantly ran better, but I was not too impressed yet (But Maybe I should be?). The boat came up to a plane fairly easy, got up to about 3000RPMs fast, then it took about 1.5-2minutes and it reached 3500RPMs (at WOT), but not much more, it may have been some more if we had the opportunity to run it for a while longer.

They did put new props on it and new accelerator wires on it this year, but I do not know anything of what they really put on. One of the engies was at slightly higher RPM's 3600 and the other at around 3400.

We got up to at most 33mph. I'm hoping that a good survey will show that the boat runs as it should
 
C

cyclops2

Banned
Joined
Apr 19, 2011
Messages
1,237
Re: RPM at WOT?

You REALLY need a BOAT mechanic. NOT 1 related to the place selling the boat.

Sounds like 2 props that are WAY WAY WRONG for each engine. And or tachs that are not correct.

Can not be 2 undersized engines . just put in to sell the boat. Never believe ANY salesman... His job is to sell ANYTHING. Anyway he can.

Mechanic........Mechanic. NO boat friends are needed on this boat.
 
04fxdwgi

04fxdwgi

Senior Chief Petty Officer
Joined
Jun 10, 2011
Messages
754
Re: RPM at WOT?

Devveon said:
It was not much of a sea trial, at that time we did not get out on the lake even, but gave it a good trial.
Anyway, was out today again. They claimed that they had just replaced the sparks and it now ran great.
It defiantly ran better, but I was not too impressed yet (But Maybe I should be?). The boat came up to a plane fairly easy, got up to about 3000RPMs fast, then it took about 1.5-2minutes and it reached 3500RPMs (at WOT), but not much more, it may have been some more if we had the opportunity to run it for a while longer.

They did put new props on it and new accelerator wires on it this year, but I do not know anything of what they really put on. One of the engies was at slightly higher RPM's 3600 and the other at around 3400.

We got up to at most 33mph. I'm hoping that a good survey will show that the boat runs as it should
Click to expand...

Those engines should be hitting the 4500 RPM range. 3600 is way off and in both engines, it is something common. Is there 6" of hair hanging off the hull from sitting (hull very dirty w/ growth). If hull is clean, then my guess would be wrong gears or props, or maybe hull is water logged and too heavy.
 
You must log in or register to reply here.
Top