454 Crusaders 3000 max rpm

[adrewoh]

I have an 85 f36, it's my third season with her. Last fall right before pull out, noticed water in my oil in the port engine and stbd engine transmition didn't go fwd and was losing fluid. I repaired both, but now I max out rpms at 3000. I get 25-27 mph, run great, no sputter, no stall....just burying the throttles now and never did before. Don't know if this is related to the work I did or just another issue to deal with. I usually run around 3000, but wasn't getting much over 22 mph, but have gone up to 3800. Props are 20x21's, tuned up this spring. ...carbs were rebuilt spring 2015, new fuel lines, new fuel filters, new hoses...

What should I look at? What rpm should wot be?

[gitchisum]

Sounds to me to be more of a tach issue, than an engine issue. If you're doing 27 mph at "3000" rpm, your tach is lying to you.

Are both tachs telling you the same reading? WOT is spec'd to be about 4,000 rpm, with a top speed about what you are getting.

[adrewoh]

Tachs read the same, I'll check them. ..thanks

[prowlersfish]

Did you change the pitch on the props ? Or maybe the shop got it wrong ? With higher speeds at lower rpm there are only a few things it could be . start with the tachs then check the props . One other thought you repaired the trans ? did you swap it out for another ?

[adrewoh]

Didn't change the pitch of the props--interesting about the shop getting it wrong--I have spares that are 20x20 and the boat doesn't perform as well with them.

Took out the tranny to have repaired. They replaced the clutch plates and a seal. I also got a new damper plate--the old one rattled at idle speed. ..new one great!!

I noticed the rpm issue last weekend--had 10 people on the boat and couldn't get over 18mph and was maxing out the throttles--getting 2700 rpm. I cleaned the flame arrestor and one carb had the rear butterfly sticking--cleaned up and that's when I got better speed. Haven't had a full boat again to see if I can get 25mph with the added weight

[larryeddington]

Just me on my tri-cabin with crusader 270s with clean bottom I now get 24-25 mph by GPS. Props are 20x17 engines turning 3700. I am thinking about pulling props and have them de pitched to 20x15 should add 400 rpm and speed as well. Trannies are 2 to one I think.

[adrewoh]

Wow, that's good speed with 270's. How does it sound running at 3700? I'm complaining about not getting over 3k although that's what I usually run at. ..just want to be able to. ..but the fuel I go thru over 3k is insane. I got 1st place in the club for gas usage last yr

[adrewoh]

I put new fuel filters in, then the starboard engine wouldn't start at all. Realized I only put a new fuel pump on the port engine last year. So ordered one for starboard. Hopefully all will be well. Updates after....

[larryeddington]

The 270s just purr like a kitten but should get 4k rpm hence the de pitch of prop sometime. Seems the 350 chevys easily like higher rpms.

[rickalan35]

TriCabins are pretty fast. No surprise.