TO SLOW?

[mike a]

Hi I have a 1986 checkmate Ambassador it has a 350cid ( 260 hp) @ wot it will only do 51 mph @ 44000rpm. I talked to MIKE at checkmate and he said the boat should do about 62mph with a 14.25 x 22 prop. The prop that's on the boat looks to have been "redone" it has engraved on it M22 also has engraved on it 3/20 props plus? has this been reworked to a 20 pitch? The motor is all stock with the exhaust running out the prop. Can anyone help me get this boat to do 62 mph there's a Baja on my lake id like to beat!! speed and rpm is from stock gauges. Thanks Mike

[mike a]

Hi I have a 1986 checkmate Ambassador it has a 350cid ( 260 hp) @ wot it will only do 51 mph @ 44000rpm. I talked to MIKE at checkmate and he said the boat should do about 62mph with a 14.25 x 22 prop. The prop that's on the boat looks to have been "redone" it has engraved on it M22 also has engraved on it 3/20 props plus? has this been reworked to a 20 pitch? The motor is all stock with the exhaust running out the prop. Can anyone help me get this boat to do 62 mph there's a Baja on my lake id like to beat!! speed and rpm is from stock gauges. Thanks Mike

[Eriktheviking]

Thru-hub exhaust is VERY restrictive.I don't think you'll be able to break the high 50's http://www.checkmate-boats.com/infopop/emoticons/icon_frown.gifMaybe someone else can tell you about props plus engraving. I think you may want to try a 20" Turbo ,19 or 21" Quicksilver Laser prop.That would bring you RPM's up to 4800 or so.Think about putting a thru-hull exhaust setup.It will let the motor breath and the Baja's will hear you coming!

[mike a]

Thanks I have been wanting to put thru hull exhaust on it. Can I run exhaust hose to stainless tips? What about water entering the tips? Also what do I do with the old cast iron y pipe? leave it in? cap it off? can I install mufflers or will that restrict it to much.? Thanks for all the help this is a really good and informative site keep up all the good work.

[Eriktheviking]

Its easy to put thru-hulls on that style boat.You'll have to cap off the Y pipe and run 3 or 4" hose straight back to the tips which fit between the swim platforms and over the outdrive.You probably have 3" risers(elbows),so unless you want to change them to the newer style 4"(which breathe much better)you'll need some 3" tips which I see on ebay all the time, CHEAP! If you can find someone with a senator or starfire,they have similar thru-hull systems.Check'em out and see how to set up yours. http://www.checkmate-boats.com/6/ws/,s,8626072361/Graemlins/thumb.gif

[Bill]

I would not run silencers or mufflers, too restrictive and too quiet. If you run your stock exhaust manifold and risers, you more than likely will be okay with the authorities. When i was up in Green Bay, I had the DNR listen to me when I was open (exhaust) and they said I should be okay. Green Bay has about the lowest db laws I have ever seen at 86db at idle a couple of feet off of the transom. If I were you, run the 4" exhaust and tips. You can get new tips very reasonable through Livorsi Marine with internal flaps to keep the water out.

2003 ZT 240 6.2litre/Bravo 320 H.P. 25P Mirage Plus

[mike a]

Thanks Bill do you know if a 4" riser will bolt up to my stock manifold? Bill I see your running the 6.2 is that the Scorpion motor? The ZT is one really nice boat!!!! hope to own the 24 someday myself. Thanks for all your input.

1986 Ambassador 350, 260hp.

[Bill]

Mike A. I can't be 100% sure about the bolt up, but I would say yes, it should work. I would call you local Merc place, they would be able to get a definate answer. No, mine is not the Scorpion, but is one hell of a motor. Not bad to get 320 ponies out of a small block. Slap on a super charger and my ZT 240 would just scream. I love the lines of the ZT too!

2003 ZT 240 6.2litre/Bravo 320 H.P. 24p Bravo 1

[Eriktheviking]

Mike,
4" risers will bolt up.I know a couple people that have done it. Once you look inside them you'll see the difference we're talking about! http://www.checkmate-boats.com/6/ws/,s,8626072361/Graemlins/thumb.gif

[2003cobra]

HI MIKE
JUST WONDERING IF YOU EVER GOT ANYWHERE WITH YOUR MPH PROBLEM AS I AM HAVING THE SAME WITH MY 84 ENFORCER WITH SAME MOTOR AS YOU.I CAN ONLY GET 49 GPS AND53 SPEEDO.IF YOU WERE ABLE TO GAIN SOME MPH LET ME KNOW WHAT YOU DID.I ALREADY HAVE THROUGH HULL EXHAUST.I HAVE A 21 PITCH STAINLESS SPINELLI BROTHERS AND TURN 4400 RPM, STOCK 1.50 DRIVE