HSiii

[Les Young]

I have a 1993 Sprint 255 with a 1992 70h.p. Johnson. I believe the tach wasn't adjusted when the engine was switched from an 48h.p. Rude to the 70 h.p. Johnson. Tach was saying 7100 rpm. There are no clicks on the pulse screw on the original Teleflex tach that came in boat. I adjusted it & it says 5900 rpm with a 13&17 aluminium prop. I back out & cruise at 5400 rpm & it actually sounds about right. When turning 5900 by the tach , it definitley sounds like it's winding tight to me. What prop do you think I need & where should this Teleflex tach be adjusted to ensure accuracy. Thanks , Any help from you or anyone else is truly appreciated.

 

[hwsiii]

Re: HSiii

Les, I show you have a recommended WOT range of 5,000 to 6,000 RPM and a gear ratio of 2.42:1, please check this for me. If this is true then you should be running a 17" pitch prop. I am sorry, I am not qualified to help with your tach problem, but 5,900 RPM sounds right for your RPM with this prop. You can buy a tiny tach for about $ 40 and that may be a good idea.


H

 

[countvlad]

Re: HSiii

I have a 1993 Sprint 255 with a 1992 70h.p. Johnson. I believe the tach wasn't adjusted when the engine was switched from an 48h.p. Rude to the 70 h.p. Johnson. Tach was saying 7100 rpm. There are no clicks on the pulse screw on the original Teleflex tach that came in boat. I adjusted it & it says 5900 rpm with a 13&17 aluminium prop. I back out & cruise at 5400 rpm & it actually sounds about right. When turning 5900 by the tach , it definitley sounds like it's winding tight to me. What prop do you think I need & where should this Teleflex tach be adjusted to ensure accuracy. Thanks , Any help from you or anyone else is truly appreciated.

if you dont have any adjustments on the tach then i doubt you can do anything about it.... buy a new one and most of the worries will go away

 

[junior1113]

Re: HSiii

most tachs dont have adjustments. you have a rev limiter at 6200 or 6700. so you didnt hit 7100. new one is your best bet. 5600-5900 is great wot rpm for your motor. what size prop is on there now?

 

[Les Young]

Junior1113

Junior1113

It has a 13X17. Guess i'm just used to a v6 & this little 3 banger sounds a little tight to me.

 

[countvlad]

Re: HSiii

most tachs dont have adjustments. you have a rev limiter at 6200 or 6700. so you didnt hit 7100. new one is your best bet. 5600-5900 is great wot rpm for your motor. what size prop is on there now?

i didnt mean adjustment as trying to tweak the gauge what i ment by adjustment was changing the poles on it to match the new motor poles... sry for the confusion