power out of 1978 85hp johnson

[fpctim]

i have an 18 foot stinger bass boat with the 85hp johnson on it.i added power tilt and trim to it but the boat does not seem as fast as it should be.i read 30 on the speedo.am i wrong or should this boat go alot faster.the carbs are rebuilt i have great compression.how fast should this motor push this boat?

 

[DJ]

Re: power out of 1978 85hp johnson

1. Don't ever trust a boat speedometer. Borrow a GPS.

2. Most important, what is your wide open throttle (WOT) RPM? Without that, anything you do is a guess.

 

[fpctim]

Re: power out of 1978 85hp johnson

not sure of rpms tech is not hooked up,but i had a 14ft bass boat with a 50 o n it and it was alot faster,what pich prop should i have?

 

[DJ]

Re: power out of 1978 85hp johnson

not sure of rpms tech is not hooked up,but i had a 14ft bass boat with a 50 o n it and it was alot faster,what pich prop should i have?

That boat is a completely different animal. Apples and oranges.

You cannot even begin to play with props until you know your RPM's.

There is no magic guess here.

 

[fpctim]

Re: power out of 1978 85hp johnson

not looking for a guess just wonder how fast the but should go thats all,it could just be me

 

[tashasdaddy]

Re: power out of 1978 85hp johnson

it all depends on the condition of the the boat, and the proper set up of the motor. set being height to the keel, angle of the trim, correctly propped to wot rpms. the boat, holding any water in the foam under the deck, properly balanced load not too bow or stern heavy. until all this is right, you will not get he max out of your boat. there really is no way of telling. it is all experimentation with each individual hull, and motor. that should answer your question. anything else is a pure guess.

 

[ezeke]

Re: power out of 1978 85hp johnson

The 18 ft (17.33') Stinger bass boats were rated for max 155 HP which makes the 85 a fairly weak combination.

If you want to get out of the hole quickly, you will need to prop to hit around 5500 or slightly better RPM at WOT.

You are probably doing ok at 30 MPH, but you should verify the RPM.

 

[Bjoe1981]

Re: power out of 1978 85hp johnson

I have a 16.5 foot Glastron CVX with an 85 and I ran 43.4 mph verified on GPS. I dont know the prop size, no numbers on it that I can see.

 

[Benny1963]

Re: power out of 1978 85hp johnson

lot of boat for and 85 ,may be able to pick it up some install tach first and waterpressure gauge ,get it up high and test some props but the 85 on that hull wont fly ,you may get a little lore out of it ,or possibly trade to 140 looper or older crossflow ,150 175 , good luck repost when ya get some rpms
on your tach and gps speed