Join the C34 Association Today!
[C34 Home] [C34Tech Notes] [C34 Tech Wiki] [Join!]
Please login or register.
Advanced search  

News:

Pages: [1] 2 3   Go Down

Author Topic: Throttle Speed Adjustment  (Read 5878 times)

0 Members and 1 Guest are viewing this topic.

TortolaTim

  • Forum - Petty Officer 3rd Class
  • ***
  • Karma: 2
  • Posts: 51
    • View Profile
Throttle Speed Adjustment
« on: August 12, 2021, 02:14:41 PM »

I have an '89 with the M25XP. Manual says 3200 is the max RPM. I was perusing the forum here and read a bunch of threads about cruise RPM and speeds, etc. I realized that my tach reads 25-2600 RPM at WOT. I'm pretty sure that's the way it's been since I've owned the boat (2 years). I know the tach can be less than accurate, so I ordered a laser tach from amazon to see what it's actually turning.
My question is...If it is indeed turning this lower speed, is it just a matter of adjusting the throttle set screw on the engine until it's reaching 3000-3200? I looked at it and it has plenty of room to be adjusted for the throttle to open wider. Secondly...can this be done at the dock in neutral, or should I be in gear out on the water? The engine runs very well other than this. I've not had any issues with it at all.  TIA!
Tim
Logged
Tim Callico
1989 C34 #957
M25XP
St Johns, FL

Ron Hill

  • Forum - Master Chief Petty Officer of the Navy
  • ********
  • Karma: 61
  • Posts: 7749
    • View Profile
Re: Throttle Speed Adjustment
« Reply #1 on: August 12, 2021, 02:31:09 PM »

Tim : "My question is...If it is indeed turning this lower speed, is it just a matter of adjusting the throttle set screw on the engine until it's reaching 3000-3200? I looked at it and it has plenty of room to be adjusted for the throttle to open wider. "

YES, MAYBE  Just loosen the screw on the cable stop and see if the throttle arm will move and give you a higher RPM!??!

A thought
« Last Edit: August 24, 2021, 02:30:54 PM by Ron Hill »
Logged
Ron, Apache #788

Stu Jackson

  • C34IA - Secretary
  • Forum - Master Chief Petty Officer of the Navy
  • ********
  • Karma: 72
  • Posts: 8101
    • View Profile
Re: Throttle Speed Adjustment
« Reply #2 on: August 12, 2021, 06:00:54 PM »

Quote
"My question is...If it is indeed turning this lower speed, is it just a matter of adjusting the throttle set screw on the engine until it's reaching 3000-3200? I looked at it and it has plenty of room to be adjusted for the throttle to open wider. "


Tim,

NO

First you have to determine what the speed actually is.  That's first.

If indeed at WOT as it is now, it is truly turning at 3000 (or 3200, mine's 3000), THEN and only then you have a choice.

1.  Play with the back of the tach in the cockpit and see if you can adjust it.

2.  Don't bother, just make up a handy dandy cheat sheet where 2600 = 3000 (or 3200) and all the in betweens.

In the big scheme of things it simply doesn't matter.

The very LAST thing I would do is adjust the throttle set screw.  After all, once upon a time they adjusted it at the engine factory.

If, however you feel you are losing speed at WOT (real) because of this possibly phantom 400 or so rpm, then, and only then, open 'er up.

Good luck.
« Last Edit: August 12, 2021, 06:02:48 PM by Stu Jackson »
Logged
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."

TortolaTim

  • Forum - Petty Officer 3rd Class
  • ***
  • Karma: 2
  • Posts: 51
    • View Profile
Re: Throttle Speed Adjustment
« Reply #3 on: August 13, 2021, 05:12:59 AM »

Can the RPM test be done in neutral at the dock, or should it be under load out on the water in gear?
Logged
Tim Callico
1989 C34 #957
M25XP
St Johns, FL

scgunner

  • Forum - Chief Petty Officer
  • ******
  • Karma: 9
  • Posts: 632
    • View Profile
Re: Throttle Speed Adjustment
« Reply #4 on: August 13, 2021, 07:10:50 AM »

Tim,

You can test RPM in gear under load in your slip if your dock lines are good and you've got fore and aft lines on both sides. I've run mine up to about 2400 RPM, which is my normal motoring cruise in the slip with no problems. It makes doing checks easier when you can jump on and off the boat.
Logged
Kevin Quistberg                                                 Top Gun 1987 Mk 1 Hull #273

Stu Jackson

  • C34IA - Secretary
  • Forum - Master Chief Petty Officer of the Navy
  • ********
  • Karma: 72
  • Posts: 8101
    • View Profile
Re: Throttle Speed Adjustment
« Reply #5 on: August 13, 2021, 09:24:22 AM »

I do not see a difference in the rpms at WOT out of gear, in gear tied to the dock, or out in open water.
Logged
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."

scgunner

  • Forum - Chief Petty Officer
  • ******
  • Karma: 9
  • Posts: 632
    • View Profile
Re: Throttle Speed Adjustment
« Reply #6 on: August 13, 2021, 09:53:33 AM »

Stu,

You're probably right but there may be a difference in max achievable RPM under load(in gear) vs. no load. I don't know since I've never found the need to test for a difference between the to. I just mentioned it so Tim could run tests without the need to take the boat out.
Logged
Kevin Quistberg                                                 Top Gun 1987 Mk 1 Hull #273

Ron Hill

  • Forum - Master Chief Petty Officer of the Navy
  • ********
  • Karma: 61
  • Posts: 7749
    • View Profile
Re: Throttle Speed Adjustment
« Reply #7 on: August 13, 2021, 10:05:01 AM »

Tim : I assumed that with your laser tach you were first going to look at the correctness of your engine tach!!  You did say that in your opening post!!

Mark the throttle cable as to its present position, start the engine, loosen the throttle cable stop screw, move the throttle lever on the engine FWD and see if you actually increase the engine RPM ??  Then decide where you want that throttle to be set at.
That throttle adjustment screw was placed where it is by someone at the Catalina factory after the pedestal and engine were installed.  It should (maybe?) have been checked while the engine was running (boat in the water) by the dealer???

Then make yourself a small chart of 4 or 5 different RPM settings on the engine tach and the actual RPM from the laser tach.  The real important setting is your 80% power for cruise.

You can fool around with the dip switch settings on the back of the tach instrument, but I've had little success with doing that!!  There is quite a formula for those dip switches!!! (wrote a Mainsheet tech note article on those dip switch settings)

Kevin brought up a point.  I believe that in gear the boat RPM might start out lower, but as the boat speed picks up (inertia) the RPM will stabilize maybe a few RPM lower than when in neutral?

A few thoughts
« Last Edit: August 13, 2021, 10:19:22 AM by Ron Hill »
Logged
Ron, Apache #788

TortolaTim

  • Forum - Petty Officer 3rd Class
  • ***
  • Karma: 2
  • Posts: 51
    • View Profile
Re: Throttle Speed Adjustment
« Reply #8 on: August 13, 2021, 10:42:09 AM »

Ron, yes I’m going to compare tach RPM Vs Laser tach next week when I get home. Just ordered one from Amazon. My concern is more about whether I’ve been actually making the published 3000-3200
at WOT. It’s always shown about 25 or 26 on the factory tach.
I’m on my way to Europe right now, so after I get back Monday take it out and check with the laser. I’ll write down the RPM corrections and report my findings.

Thanks all for the advice
Logged
Tim Callico
1989 C34 #957
M25XP
St Johns, FL

Ron Hill

  • Forum - Master Chief Petty Officer of the Navy
  • ********
  • Karma: 61
  • Posts: 7749
    • View Profile
Re: Throttle Speed Adjustment
« Reply #9 on: August 13, 2021, 02:37:03 PM »

Tim : You might lookup that article I wrote on the Tach Dip Switch settings, because I have a picture of the Default settings (M25XP with stock alternator) in that article.  A PO just might have changed them!?!  Also that formula for settings of a new alternator with a different pully size!!

A lot of information in these old Mainsheet tech note articles!!   :clap

A few thoughts
Logged
Ron, Apache #788

Stu Jackson

  • C34IA - Secretary
  • Forum - Master Chief Petty Officer of the Navy
  • ********
  • Karma: 72
  • Posts: 8101
    • View Profile
Re: Throttle Speed Adjustment
« Reply #10 on: August 13, 2021, 03:21:55 PM »

Tom, the Teleflex tach manual is in the tech wiki, under manuals.
Logged
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."

KWKloeber

  • Forum - Master Chief Petty Officer of the Navy
  • ********
  • Karma: 35
  • Posts: 4222
  • "Positive Impact" 1984 C-30 mk-I #3573 trbsfk M-25
    • View Profile
Re: Throttle Speed Adjustment
« Reply #11 on: August 18, 2021, 09:23:32 AM »

Do we KNOW that the factory “screwed with” the adjust screw, or was the cable simple attached to the engine exactly how it came from the other factory (Oshkosh)??  If we don’t know the procedure I’d think it’s a huge jump to say CTY adjusted anything, and simply started er up and checked the tach that there was some reading at all, not necessarily accurate.
Logged
Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
So throw off the bowlines.  Sail away from the safe harbor.  Catch the tradewinds in your sails.
Explore.  Dream.  Discover.   -Mark Twain

Stu Jackson

  • C34IA - Secretary
  • Forum - Master Chief Petty Officer of the Navy
  • ********
  • Karma: 72
  • Posts: 8101
    • View Profile
Re: Throttle Speed Adjustment
« Reply #12 on: August 19, 2021, 05:53:04 PM »

Do we KNOW that the factory “screwed with” the adjust screw, or was the cable simple attached to the engine exactly how it came from the other factory (Oshkosh)??  If we don’t know the procedure I’d think it’s a huge jump to say CTY adjusted anything, and simply started er up and checked the tach that there was some reading at all, not necessarily accurate.

I've read every single C34 tech note, from as early as 1987 before they even called 'em tech notes.  While your binary choices, Ken, are quite possible, i.e., they did or they didn't, I find it hard to believe that they did nothing.  Why?  Because in all of those years I did not ever read of a recurring all encompassing repeated situation where C34 skippers were ALL complaining that the WOT on their engines were all of whack, high or low.  I am quite sure Ron Hill would have reported THAT glitch!!  The consistent reports were that it was 3000 and that's pretty much what everyone reported.

It could well be that CTY just slapped 'em in and depended on the engine's builders to have set the MAX set screw properly.  Maybe give 'em a little credit for trying or checking?

So, yeah, I guess you're right again, still bashing the builder, who just happened, by chance, accident, serendipity, witchcraft and voodoo to get 1801 hulls and engines built that just by happenstance all are correct.

I should be so lucky.  :D
« Last Edit: August 19, 2021, 06:07:14 PM by Stu Jackson »
Logged
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."

KWKloeber

  • Forum - Master Chief Petty Officer of the Navy
  • ********
  • Karma: 35
  • Posts: 4222
  • "Positive Impact" 1984 C-30 mk-I #3573 trbsfk M-25
    • View Profile
Re: Throttle Speed Adjustment
« Reply #13 on: August 19, 2021, 11:21:08 PM »


So, yeah, I guess you're right again, still bashing the builder, who just happened, by chance, accident, serendipity, witchcraft and voodoo to get 1801 hulls and engines built that just by happenstance all are correct.

I should be so lucky.  :D


Stu,

:donno:

I don't have one CLUE what you are babbling on about except, per usual, trying to blow something way out of proportion? 

If I was a builder (CTY) and a component (engine) came to me to install and the engine mfgr set to specs -- I wouldn't think that my attaching a cable required "setting" anything -- so I wouldn't want to screw with it. 

So my wonder was, did CTY adjust the engine after installing the cable?  Or if something is amiss, might it have shipped from Oshkosh that way?  Or did a PO adjust something?  Or (as you mused) is the tach off?  Or, is the governor getting messed up.  Or..... (insert another cause.)

That's why I ASKED, and thought maybe someone knew for sure whether CTY did further adjustments.  I have no clue why you would connect adjusting or not adjusting has anything to do with bashing CTY.   And it has nothing to do with Tech Notes, or every boat that came off the line having an incorrect setting.

Get back on your meds.  Please.
« Last Edit: September 08, 2021, 07:24:31 AM by KWKloeber »
Logged
Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
So throw off the bowlines.  Sail away from the safe harbor.  Catch the tradewinds in your sails.
Explore.  Dream.  Discover.   -Mark Twain

TortolaTim

  • Forum - Petty Officer 3rd Class
  • ***
  • Karma: 2
  • Posts: 51
    • View Profile
Re: Throttle Speed Adjustment
« Reply #14 on: August 24, 2021, 12:36:35 PM »

Update on the RPM discrepancy. We took the boat out and compared laser tach with cockpit. Most RPM settings only varied by a 50 or less, full throttle (obtained by me moving the throttle on the engine) was 3000. Looks like I just need to adjust the cable so the throttle on the binnacle can move the lever (engine)  all the way to open. Looks like all is well. Thanks for the info! Now on to the next project!
Logged
Tim Callico
1989 C34 #957
M25XP
St Johns, FL
Pages: [1] 2 3   Go Up