Running out of Puff

"Hi Guys
I have a pair of 292

"Hi Guys
I have a pair of 292ci 6cyl chevies in a bertram 25.
The Starboard engine makes full revs easy but the Port engine will not exceed 2200 revs no mater what.
The engine doesnt die or breakdown in any way but it will just not rev above that 2200 mark under load.
The engines are fitted with standard points ignition systems and the fuel is deliverd through standard 350 Holley carb's.
The ignition side seams perfect so I am thinking the carby on my port engine may be under sized in the jetting area, does that sound feasable? The throttle butterfly is definitly completely open at the full throttle position,
Any ideas.
Regards
Peter"

"I doubt the Carb is under-siz

"I doubt the Carb is under-sized,.....

I'd sooner Think that it's Full of Crap,+ partially Plugged........."

"Has it been like this since y

"Has it been like this since you've owned it, or is this something that just started happening?"

Check the timing advance with

Check the timing advance with a light. I suspect the advance mechanism in the distributor is not moving properly (ie: it's rusted).

Jeff

"Thanks for the feedback,
its

"Thanks for the feedback,
its been like it since I have owned the boat, the carburetta is clean and free from any contamination, the advance curv seems fine, I have not been able to determin if it is reaching max advance at revs but the degree of advance attained is very similar to the starboard engine which is running perfectly.
The fuel filters are relativly new (about ten hours use ) and the pickup screen in the tank is clean as well.
The Carbys do have different list numbers on the air horns though.
Any more ideas????
Regards
Peter"

"I'd have to assume that i

"I'd have to assume that it ran correctly at some point following initial installation.
Therfore, we have to figure out what has happened to that engine that didn't affect the other.
Things I would check:
- fuel screen on the inlet to the carb (where the fuel line connects.) most carbs have a screen there to catch the chunks of the fuel pump when it craps out.
- is the float bowl filling up with fuel? The float may be stuck or there is something clogging the needle valve.
- is the choke opening? This would also cause dark brown smoke and black residue on the transom at the water line if the choke wasn't opening properly.
- if it idles ok and revs up when you pump the throttle, there may be something clogging the high speed jet.
- Is the prop damaged?
- Is the fuel pump delivering enough fuel... you can install a test gage in the fuel line and check it against the specs in the manual.
...just a few things to look at."

"Thanks again for some tips Tr

"Thanks again for some tips Troy,
I have pretty well disscounted all of what you suggested. I am a little suspicious of fuel flow so that is one of the things i intend to check in the near future. I was already debating the idea of removing the mechanical fuel pumps and installing electric pumps but I would like to test the flow rate first.
Anyway, thanks everyone for your feedback and tips, when I get a solution I will post it for future reference.
Regards
Peter C"

"You state that it's been

"You state that it's been this way since you bought the Boat,......

Have you Checked,+ Verified that the Props Match,..??.....
How about the Transmission, or Outdrive Gearing,..??..??...

How about a Compression Test on the Motors,..??..??"

"Thanks Bondo for your input,

"Thanks Bondo for your input, I have already verified the outdrive ratios match, the props are identical and have had the heads of both engines in the last 18 months for service.
Compression test results are within 10 to 12 psi of each other on both engines and bores are in fairly good condition considering the age of the blocks.
Its a tricky little problem no doubt, but I am still leaning toward a fuel problem as the engine runs beautifully under a no load situation and also runs very smoothly up to around that 2200 rpm mark under load where it just wont rev any harder.
Its a bit of a head scratcher but there are still a couple of basic tests to be done before we bring in the vet to have it put down ;-)
Cheers
Peter C"

"Peter:

Do us all a favor:

"Peter:

Do us all a favor: When you figure this thing out, write a new post and let us know what the problem was. Okay? ANd good luck!

Jeff"

I'm betting on the fuel pu

I'm betting on the fuel pump.

"Do you know that your tach is

"Do you know that your tach is accurate?
What does it do at WOT? There must be some bogging, popping, something. If you suspect the carb, swap it with the one from the other engine.

This isn't rocket science. Fuel + compression + ignition = Fire. One of the three is missing."

"Hi Rick
It is a good one, WO

"Hi Rick
It is a good one, WOT on my Starboard engine under load is approx 3600rpm the Port will only make around 2200rpm, there is no significant bogging down up to that point, no popping or any other hesitation actually it probably runs slightly smoother than the Starboarb engine up to its self impossed top speed.
As far as I can tell the tacho's are pretty accurate as I have compared their readings to a hand held unit.
Your exactly right, it is not rocket science and as mere mortals we can tend to over analyse these things.
Troy could very well be right with his suggestion of the fuel pump, maybee a valve in the pump cavitating under high demand or the activating lever worn down.
Who knows, I will keep looking and you can be all assured I will post the cure when I find it.
Watch out for running out of puff 2 over the next month.
Thanks again everyone.
Cheers
Peter"

"Thinking Outside the usual Bo

"Thinking Outside the usual Box here,......

Has it been Overheated,..??....
Has it been Run, without a Good Flow of Water,..??....

I Ask only because, I seen an Exhaust Flapper burn off,+ lodge in the housing, blocking the Exhaust Flow,......
But that was on an Outdrive.....

If you can attach a Vacuum Gauge to a Full Vacuum port,......
That's a Really Useful Tool for this kind of Diagnostic work......"

"Hi again Bondo, there is no d

"Hi again Bondo, there is no doubt about it, this is a great site for workshoping problems.
No to the overheating problems and water flow is good.
Your right about the Vacuum gauge being a great tool for this type of diagnostic work and I have a very good one, so if the guy I leant it to ever works out where he has put it I will certainly be able to put it to good use.
My next step is to check fuel flow rates and then move on from there.
I will keep you all posted.
Great Suggestions.
Good Advice.
Thanks again everyone.
Cheers
Peter"