rpm,s for a 4,3 v6

[bobmoore]

a freind of mine just bought a 1988 sunbird 19.5 ft cutty with a 4.3 v6 motor, how can i find out what the max rpm,s are. right now the boat runs out at 3700 rpm and about 36 mph.he,s got a 14.24x19 stainless prop on it . he just bought the boat , he hasn,t had one for 25 yrs. the guy he bought it from claimed it would do 48 to 52 mph..but when he had it out he did not trim the motor. could that be the difference.the boat only has 119 hours on .<br /> thanks <br /> bob moore

 

[Lark40]

Re: rpm,s for a 4,3 v6

Gee, I just bought a boat with that same engine. Owner said it would go 52 mph. I knew better. Clocked at 39 mph using two GPS's. Well, he SEEMED honest.<br /><br />Anyway, the two-barrel carb version has a top rpm range 0f 4200-4600 rpm and the four-barrel has a range from 4400-4800 rpm.<br /><br />A 21" pitch prop didn't help my 22' Starcraft, but it may speed up your smaller boat.

 

[upsman]

Re: rpm,s for a 4,3 v6

I have a 1989 Four Winns cuddy 21' with the 4.3L SS prop. at 4600 RPM (trimmed up) smooth water and 4 in the boat I'm doing 48MPH according to my GPS. Trimming up will gain you a min. of 10MPH and conserve your fuel by greatly reducing drag. Consider changing prop if you can't turn the 4600 RPM trimmed and loaded. Be careful trimming up too high on rough water as you loose stability! Hope this helps.