Prop difference?

[lathehand]

The prop probably has something to do with it but your talking 900 rpm diffrance and your running a 19 inch pitch.You don't say if either boat is kept in the water or not or if any bottom paint is used on either.It could also be your older boat could be getting water logged. I beleive all these things are all possable reasons why.I would happy to see my 77 cuddy hit 35 mph

[spareparts]

if your boat jumps his, and you are only showing 3500 at WOT, your tach is bad(or miss adjusted). What pitch is he running? BTW, base timing should be no higher than 4 degrees BTDC if you are running 87 octane . I've run them as high as 9 degrees but that was with good 89 no ethanol fuel in a light boat with a different carb, protonix ignition, colder plugs, and a very special prop

[cfelton]

Well I pulled the prop again and the only number I found is stamped way inside the web and it is 22.My buddys prop is a new Quicksilver 19 pitch prop. Never heard of a 22 pitch prop but who knows its an Elite 1. Im running 93 octane non ethanol fuel, with the timing at 4 degrees and a Pertronix ignition. The tach is the factory installed tach so it could be off some. My neighbor gave me a quicksilver 23 degree prop but I think that would make it worse. I guess Ill try to get my hands on a 19 pitch prop and try that. Both boats stay on trailers but Im wondering what the weight difference is between a 77 and a 85 V20. The stern of my boat sits about 3 inches lower than the 85 at rest, and at WOT both of us were trimmed up to almost porposing Thanks guys!

[THEFERMANATOR]

I agree with spare, sounds like your tach is off. If your jumping on plane, but not keeping up on the top end while burning more fuel, then you probably have a prop without alot of rake, and a good bit of cup. Prop design has alot to do with how a boat runs out and planes. I'm a fan of the large diameter 3 blade props myself, but they don't normally reccomend them for smaller engines due to the amount of bite they get down low in the RPM range. You need to take your prop to a prop shop, and let them tell you what pitch it is. Most any prop shop will have a pitch gauge to check it. If he has the old style generic quiksilver, that is a pretty crude and basic stainless prop, with ALOT of room for improvement. Or if it is one of the newer quiksilver props, it could be just about anything since MERCURY changed and used QUIKSILVER as there generic prop series. All I could find for the ELITE SS is it is a name they include with most of MERCURYS props now, so without a cup series number, who knows what it is.

A good example of prop series differences would be like when I changed from a HIGH FIVE to a TROPHY PLUS on my flats boat I had. Both props were 21 pitch props, both were basically teh same diamter, and both props tached out close to each other on the top end. The high five topped out around 5300RPM's at 51 MPH, and the TROPHY plus topped out at 5600 RPM's and 62 MPH before the wife made me let out of it(it was still climbing). Or the SEA RAY I did a few years back. Ran it with a 17 pitch old style quiksilver prop and it redlined at 5000 RPM's and only hit about 25 MPH. Swapped over to a large diameter MIRAGE style prop of 16 pitch, and it topped out at 4700 and ran upper 30's. Less pitch turned less RPM's, and was faster.