1983 v4 90 prop help

[FGL]

Hi, I have a 1983 v4 90hp on a 17' fish and ski, used to run 45 at WOT, thats when I bought it. I have always wondered if was designed to do that speed or if maybe it went faster when it was new. Anyway, prop has been slightly dinged up, (my fault), only does about 40-42 now. I would like to buy a new one, and get mine reworked for back up. How do I know which one to buy? Should there be a model number on this one to reference, or do I need to do some measureing. I would be greatful for any help.<br /> Thanks<br /> Frank

 

[G DANE]

Re: 1983 v4 90 prop help

If its an OMC prop, part number will be stamped on hub, just beside the propnut. Otherwise pitch and diameter usually is casted in the base of one blade. I would say you ought to turn a 19" pitch, diameter 13 1/4 ". This is a perfect opportunity to hit the perfect prop. Does your boat have a tach ? It should hit 5800 rpm at wot with an average/light load. Many propshops will allow you to borrow and test a prop for only one ride. Tell us what rpm you had ? How high is the antiventilation plate, compared to a straight line from bottum of boat ( keel )

 

[FGL]

Re: 1983 v4 90 prop help

it runs at about 5500 WOT before it lost some power, now 5300 at 40mph, I will look for that number on the prop. The guy I bought it from says it used to run about 45mph when he first got it.<br /> Thanks Again

 

[funpilot]

Re: 1983 v4 90 prop help

I used to run a 19" pitch prop on my 1990 90hp V4. When the boys got a bit bigger, I switched to a 17" as they were complaining about hole shot when they got around 200 lbs. Since it was about a 10% reduction in pitch, speed at any give RPM dropped about 10%.<br /><br />They aren't around as much anymore, and I really liked the way the boat performed with the 19" pitch better. So, I'm thinking of swtiching back.<br /><br />At least these are my impressions on my 17' aluminum fish and ski.<br /><br />take care,<br />fp

 

[FGL]

Re: 1983 v4 90 prop help

Well I can't find any numbers on the prop at all...

 

[funpilot]

Re: 1983 v4 90 prop help

I'm going to take a WAG swipe at the no numbers on Prop thing.<br /><br />The diamater of the prop is just that. You should be able to check the diamater by measuring.<br /><br />The pitch is the distance the prop would move in the water in one revolution, so measuring it is probably a bit harder, but (with nothing to confirm this) I would bet that if you took the run of one prop blade (how much distance it covers from the rear of the prop to the forward end of the prop) and multilplied it by three (assuming three blades) you would come close to the pitch.<br /><br />Or... someone who knows can feel free to shoot me down. I might stop by my shop later and just check to see if you can measure a prop that way. I have to swing by the airport anyway...<br /><br />fp

 

[Solittle]

Re: 1983 v4 90 prop help

Any prop shop will be able to tell you. They have all th jigs & tools.

 

[FGL]

Re: 1983 v4 90 prop help

Thaks for that info

 

[funpilot]

Re: 1983 v4 90 prop help

Hey SoLittle... I like that answer a whole lot more than my convoluted approach!<br /><br />regards,<br />fp