Triton A4 RPM

gone2ddogs · Post by **gone2ddogs** » Tue Apr 29, 2008 3:38 pm

I've installed a tachometer on my '59 EC Triton and when motoring at full throttle it shows my Atomic 4 is only turning 1900 rpm. This seems a little low to me. What is the normal cruising RPM on a Triton with an A4?

John Ross
Triton #15 Yawl

bcooke · Post by **bcooke** » Tue Apr 29, 2008 3:47 pm

1900 isn't at all uncommon. That is max for a lot of installations. I seem to remember 2200-2400 being the ideal range which makes more sense to me.

What kind of propeller are you using?

Figment · Post by **Figment** » Tue Apr 29, 2008 4:32 pm

1900 is a bit low, but not shamefully so. How fast are you trying to go? I get hullspeed at about 1700 rpm, I think. Anything beyond that is just unecessary abuse.

Tune the ignition timing, then tune the carburator jet. You'll probably pick up another hundred.

gone2ddogs · Post by **gone2ddogs** » Tue Apr 29, 2008 5:15 pm

I just have the 2 bladed prop that was on the boat when I got it. I don't know the pitch or Dia.

John
Triton #15 Yawl

bcooke · Post by **bcooke** » Tue Apr 29, 2008 5:54 pm

I never used my 2 bladed propeller but I have heard the 3 bladed Indigo lets the engine turn faster.

I don't know if I get hull speed at 1700 but I certainly get over 4 knots - probably closer to 5. That seems to be a good spot for economical cruising. With the throttle full open I think I get about 2100-2200 rpm (with the 3-bladed Indigo prop) and the stern is really squatting and I am pushing around a lot of water. I hate to post max speeds because someone will always call me on it or claim to get another 2 knots. Let's say 5.5-6.0 max speed in calm water. For that extra 300 rpm's though I am really just burning a lot more fuel and making more noise.

The extra revolutions will probably only help when bucking some waves.

Tune it like Mike said and you might just be surprised.

bcooke · Post by **bcooke** » Tue Apr 29, 2008 5:57 pm

P.S.

Cool!

Another blog to feast upon. Now don't be shy with your updates :-)

Zach · Post by **Zach** » Tue Apr 29, 2008 7:44 pm

I second the blog accolades!

Gotta love pictures. (Grin!)

Zach

gone2ddogs · Post by **gone2ddogs** » Thu May 01, 2008 1:33 pm

When I finally get the GPS installed I should be able to tell how fast I'm going at 1900 RPM. I suspect its fairly close to hull speed.

John
Triton #15 Silver Girl

gone2ddogs · Post by **gone2ddogs** » Wed Jun 04, 2008 6:36 pm

On an overnight cruise with my wife we were motoring out and the engine kept running slower and started misfiring. On closer examination I found the choke cable had come loose and the choke was completely shut. After fixing the choke now I get 1700 rpm at just above 1/2 throttle and closer to 2100 at full tilt.