shekmark

Had the boat out yesterday first time in NJ. 454 Bravo one with 375 hp approximately. Mirage 21 plus. Couple of things I noticed. Trim button is hard to push and vague. The dash gauge barely moves to indicate that the drive is actually trimming up and down though I did get about 300 more rpm when I hit the trim up . The water to damn murky to see the drive. Max rpm was only about 4900. I believe I should have been able to hit 5400 or 5500 according to previous owner and others talking about this prop. Max GPS speed only around mid 40. Doesn't seem right. Also a fair amount of porpoising Do these boats like a certain trim tab position ? Any thoughts?

Crude Intentions

iTrader: (1)

Speed seems way off. I trim for feel. It comes with wheel time. Assuming you have a 1.5 drive and an accurate tach. Also using 45 mph since you said mid 40s that's 31% slip. Crazy high.

Fischan

Shekmark, I also think you have something strange going on there. My 242 has a fairly stock 502 but it spins a 23p mirage to 5300 rpm(if the tach is accurate) to a gps best speed of 62 so far. I noticed with mine porpoising can come on quick if I trim up too fast. I'm still learning just like you though. This is my first sport boat too. Mine seems to take off best with the tab settings at 14port and 9 starboard. The drive tucked all the way in then 1 click out on the drive so it doesn't bind the u-joints. Once on plane I can click the drive out about 2 seconds at at time with pauses in between to see how it responded to the change. If I trim out too fast mine will porpoise too. I could be totally wrong in procedure too! If I am, hopefully some of the more seasoned members will chime in and straighten us both out!

sprink58

Sounds like it's time to have that prop looked at...if the tach is right. Sometimes older tachs will play tricks on you. If that prop is right at 4900 RPM with a 1.5 gear you should be in the low to mid 50's with that boat. Also...check your trimp pump to make sure the fluid level is correct.

Fischan

Sprink58, Do the single engine 242's need bow lifting or stern lifting props?

tpenfield

I got 48 mph on my 242 (1991 model) with 330 hp 454 engine and Bravo drive. About 4400 rpm.

shekmark

Sprink. What kind of fluid goes in the trim pump ? That's a good idea I will check that.

sprink58

1. Bow lifting...Formulas like to run "Heads Up"...a 3 blade 21" Mirage Plus that is "Dead Balls On" is your prop.If that 454 is "truly" 375 horse you might try a 23" Mirage plus. what leads you to think it's 375 as opposed to a standard 330 horse?..if it's modified it has an aluminum intake and probably a Mechanical Secondary Holley 750~850 Carb.
2. Straight 30W motor oil on the earlier ones...later ones check Mercruiser but I think it's still 30W.

Love a 242 LS...especially a '86 Flat Glass. Is it a Bravo Drive?

masi242

If this is a 454 I thought rpm range was 4400-4600, unless it`s a 502 it would be 5100 I think. The 242 loves lots of trim, many trim gauges don`t work on the dash after a while you will go by feel. My 242 with the 454 max is 4600, I run a bravo1 22p labbed a little and best I saw gps was 56. I think the boat likes a bow lifting prop. The more seat time the better.

shekmark

I bought 86242ls boat in February out in Chicago. He said the motor was about that much, though I don't think it was dyno tested. Holly carb , Wieand TeamG dual plane, Crane roller cam, forged crank, Eddie Marine exhaust, Actual estimate is 400 HP , not 375. 1.50 Bravo one drive. Yesterday I found 3000 rpm gave me around 30 mph. It was really hard to quatify anything as there was a lot of boat traffic and no wake zones. I will document more next weekend