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foggy
21-09-2006, 08:58 PM
Guys,

How do I found out what is on my engine at present. Is it stamped in somewhere because i can not find any markings. It is a 120hp Johnson 1993 model.(boat V17L) I am thinking of getting something that gives me a bit more top end speed. Currently revs in excess of 5800rpm if i ask it to and gets out of the hole really easliy, even with 4 people on board.

Any clues would be appreciated.

Foggy

Spaniard_King
21-09-2006, 09:22 PM
Sounds like its perfect to me.... if you want more top end your gunna need more HP.. like a 150

cheers

Garry

Payneful
22-09-2006, 12:55 AM
Yep second that Garry!!

Sam

davez104
22-09-2006, 07:37 AM
Should be stamped on the prop somewhere. Whats your top speed now? And when you say it revs in excess of 5800rpm, how far in excess? I have a 135 merc on mine (17L also) swinging a 19 inch pitch and can get a bit over 35 knots out of it, which is heaps, not often you would be able to do that sort of speed in the salt comfortably. But I can only get about 5400 rpm out of mine, apparently with a 17 inch prop it will over rev so will stick with the one I have.

Dave.

Cheech
22-09-2006, 07:58 AM
Graham,

I have a spare 21 pitch at home you can try if it fits. By the sound of it yours would be either a 17 or a 19. I think Mercs and Johno's are interchangeable?

Let me know.

Cheech

Noelm
22-09-2006, 08:07 AM
those old 120's love revs, keep the prop you have now, it will give the engine some extra years and no carbon build up.

BaysideMarine
22-09-2006, 10:35 PM
My old mate Noel arons who was National Service Manager for Merc quite some years bakc reported that the Merc guys in the US told him "let them rev".

An under revving engine is dangerous. A slightly over revving engine is essentially fine.

The 135 Merc spinning at 5400 sounds a bit low to me. I would go for a 17 pitch and spin at about 5800rpm. That would be a happier rpm.

What precise rpm are you achieving foggy?

Cheech, Merc and OMC props are not compatable. And a 21 would be far too tall for that boat (in my opinion).

Cheers

searaider
23-09-2006, 07:11 PM
Geday Foggy ,
I had a look at an old Ally prop I've still got from my 1996 115 Evinrude Oceonpro . Evinrude & Johno's should be similar , were both made by OMC .

The size is on the vertical section of the centre hub .
Dont really think so , but maybe it get 's covered by the washer & nut . :-/

Its a 13 1/4 x 17 , which is 13 1/4 Inch diameter & 17 pitch .
Here are some photo's .

searaider
23-09-2006, 07:13 PM
Photo of back of prop .

searaider
23-09-2006, 07:16 PM
Further back ,
She's got a few chip & bits missing ::)

searaider
23-09-2006, 07:19 PM
Last One ,
Side view

FNQCairns
24-09-2006, 06:12 AM
Foggy sounds good, how low is your leg? You may be able to go a pitch blunter (read better cruiseing speed) if you tune your 'X dimension' by raiseing your leg without any negative consequences esp if you can currently hit 6000 with a full load on wind-out at WOT, your RPMs are the reason ex-ski engines can be a top buy compared to most fishing motors with eqiv hours.

cheers fnq

foggy
26-09-2006, 07:09 AM
Thanks for your import guys. There is definately nothing stamped anywhere on the prop. Took and off a double checked. :o. I can reach a speed of 70km hr wot spinning at 5900rpms so thats probably OK after reading all of the above. I was actually hoping playing around with the prop may get me a bit bteeer fuel consumption.


Foggy