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454 low RPM

D

dhammer

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"40' Silerton Aft Cabin 19

"40' Silerton Aft Cabin 1984 surveyed for a sale getting lower RPM's Poet 3500 and Starboard 3750

Compression readings Port 126 to 145 Star 130 to 151

Having new plugs, wires, electronic magnito checked all fuel filters change, timing checked as first effort.

Does this compression tests indicate poor rpm's"
 
The fact that the compression

The fact that the compression varies by more than 10% is an indication that the engines are at the end of their life.
 
"Ayuh,....

How much Crud,&#

"Ayuh,....

How much Crud,+ Sea Life is hanging onto the bottom of the boat,..??"
 
I'm with Bondo on this one

I'm with Bondo on this one; see if the bottom is clean and the props are smacked out of whack first. Those comp readings aren't all that bad.

Jeff
 
"Okay. Bottom is clean, props

"Okay. Bottom is clean, props are okay, and motors are tuned, yet WOT rpms are a bit low. Sounds like either a bunch of extra weight has been added (it happens) or the motors are a bit tired.

Assuming the motors are straining (and that might NOT be the case) you have two options: Take a bit of pitch off the props, or rebuild the motors. The first option is by far cheaper of course.

Jeff"
 
"Or try unloading the two tons

"Or try unloading the two tons of crap that accumulates over the years. It is getting tired. Compression should be 150, you're just getting there with the best cylinders. Some good internal engine cleaner such as seafoam may put a little life back in her, especially of you have a stuck ring or two. Keep in mind, this thing is old enough to drink and a prospective buyer should understand that."
 
"[b]"Bondo, Please explain

""Bondo, Please explain Ayuh..... at the beggining of each of your posts"

Ayuh,...... Google is your Friend JB...."
 
"Ayuh,.......<[img]"http://www

"Ayuh,.......
wink.gif
"
 
"DEFINITION FROM URBAN DICTION

"DEFINITION FROM URBAN DICTIONARY

AYUH:

A bastardized combination of "ah" and "yeah" commonly used by old cronies from Maine who have nothing better to do than whittle wood in front of a convenience store waiting to be written into a Stephen King novel.

Old Fart 1: Your wife tongue your crack last night, Jessep?

Old Fart 2: Ayuh."
 
I don't think there's

I don't think there's any reason for that post. I'd like to think we are above that here.

Andrew can you please remove it?
 
I would surely be looking for

I would surely be looking for different props to increase that RPM.Might want to try having the oil tested.They are getting pretty good with that these days.
 
Go ahead boys wind them up. Bu

Go ahead boys wind them up. But you are just beating a dead horse to death a little faster.It's the begining of the end. You may get a few more runs out of them but they are done.
 
"I had my 350;s surveyed about

"I had my 350;s surveyed about a year and a half ago when I bought by boat, the engines have about 2100hrs and are original (1977). the compression range in the port engine was 155/160 the starboard 165/175. Even with the good compression they are old engines and I treat them accordingly. If your engines will pure along at 3000rpms, than don't worry about wot, your pushing them to hard and burning a ton of extra fuel. Just my opinion."
 
"I hear what you are saying Ca

"I hear what you are saying Cannonfodder,and agree that his numbers are not the best in the world.Also to my thinking is a boat needs all the right parts working together to have a chance at longevity.We do not know Don's style of boating to guess the time his engines will hold up.I know of many boaters that will put down 100 hours a year.I can also show you many marinas that have lots of boats that size that only make it to the lift for winter, and back in a given year.Thats why we have hour meters like a back-hoe....time is wear.I have seen rough engines go long and newer ones gernade over the years.I think all Don can do is keep a smile and plan ahead.Enjoy the new boat and decide for himself if its worth the investment...Todd"
 
"Don:

IF your engines are n

"Don:

IF your engines are not working hard at cruising speed, then don't worry and enjoy yourself. You can tell if this is the case by marking the throttle lever positions at cruise speed, then (motor OFF!) seeing how open the butterflies are on the carb. If the primary barrels are less that half way open, you're in good shape. But if they are wide open, and the secondaries are even partly open, then start saving your money for a rebuild. Sorry, but that's the best advice I can give you.

Jeff"
 
"Thanks everyone for your thou

"Thanks everyone for your thoughts. I had the engines tuned up this week, wires, plugs, fuel filters, new caps etc. both engines now doing 4100
RPM's."
 
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