[mikeyt]

Same with mine.....about 2-3 mph difference.

[indykoch]

Same with mine. It's almost "dead on" up to about 40 MPH, then starts reading about 2-3 MPH fast.

[PROPNUT]

Paul,
sorry so slow to respond. The prop I am running is a stainless steel Quicksilver 48-16316A4 19p. My boat is almost identical to yours, except color. I also have the 4 barrel carbeuretor. I have'nt checked my speedo numbers against a GPS so I might be full of S@$%. Can I use my Garmin GPS out of my truck?
Rick

[mikeyt]

Originally Posted by PROPNUT

Paul,
sorry so slow to respond. The prop I am running is a stainless steel Quicksilver 48-16316A4 19p. My boat is almost identical to yours, except color. I also have the 4 barrel carbeuretor. I have'nt checked my speedo numbers against a GPS so I might be full of S@$%. Can I use my Garmin GPS out of my truck?
Rick

I dont see why you couldn't use your Garmin to measure your speed. 'course it might not tell you what exit to get off at or whether or not you have arrived at your destination.

[Irace82]

I have the 4.3LX from a 88' merc. I was just curious as to whether it made a difference between the 88' and the original 93' model that came in it. I posted earlier on a different thread that i was topping out at 40mph at 4800rpms....but that was only at about 3/4ths throttle. I have a lot more throttle to give her. I have the 14in 19pitch prop so i know its not the best for top end but is the high rpms and more throttle attributed the the 88' engine? Or is that the prop choice? What speed should i be realistically getting and at what rpms?

PS i also have already checked my tach and turned it a few times like suggested. I have tried to find a place where i can test different props out but they wont me to buy one first. So im still unsure of the best choice to put on.

[mikeyt]

Originally Posted by Irace82

I have the 4.3LX from a 88' merc. I was just curious as to whether it made a difference between the 88' and the original 93' model that came in it. I posted earlier on a different thread that i was topping out at 40mph at 4800rpms....but that was only at about 3/4ths throttle. I have a lot more throttle to give her. I have the 14in 19pitch prop so i know its not the best for top end but is the high rpms and more throttle attributed the the 88' engine? Or is that the prop choice? What speed should i be realistically getting and at what rpms?

PS i also have already checked my tach and turned it a few times like suggested. I have tried to find a place where i can test different props out but they wont me to buy one first. So im still unsure of the best choice to put on.

Likely moving up to a 21" pitch prop will allow more throttle & result in a higher top end. Your situation is the other extreme of what PropNut posted (53mph with a 19" pitch prop). In both cases i would recommend using a GPS to accurately measure your speed. I would also have someone check the throttle cable linkages to see that they are set up correctly. There may have also been a gearing difference with the '88 Mercruiser motor/outdrive that was installed in your '93 boat. You should be hitting the mid 40's with the 19" or even 50-51 mph with a 21" pitch.

[Irace82]

Yeah the outdrive is brand new put on last fall just the engine is from 88'. But i will check the speed with a gps next time out. Im not too worried about the top end speed as i mainly use it for watersports i just wasnt sure if it should still be running at those rpms with the 19 pitch prop. But im taking it to the shop in the next week or so ill ask their opinion.

Thanks for all of your help this forum is great!