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How fast should it go?

mmeditz

mmeditz

New member
Well, after owning it for almost a year, I finally got it on the water. New floor, carpet, 3/4 of the new interior and most importantly the freshly rebuilt 350 engine.
With this 78 Convincer being my first ever boat, I don't know what kinda speeds I should be looking for. Has an aluminum (slightly dinged from previous owner) prop, 19p (I believe). Engine was bored .040 and mildly cammed. All else is stock.
Last Sunday, with a full 20gal fuel tank and me(280#):sssh: my speedo was right around 58mph. My buddy with his 22' 03 regal that has only 34hrs on it was also seeing 58mph as we were settling a small wager.
Sooo.... Can someone tell me if I'm in the ballpark for top speed, what I can do to go faster or even if I SHOULD go faster.
Thanks for any input!:surf:
 
My 1977 Convincer with a ragged out 302 hit a max of 53 mph (GPS), so it sounds like you're in the ballpark with a re-freshed 350. Depending on your RPM's, you should be able to step up to a 21 pitch. If you're short on funds, Turning Point's Hustler is a pretty good aluminum prop, otherwise step up to a stainless, I'd say something like a Laser II. A better prop should push you past 60. Try to get some more info like WOT RPM and GPS speed and more guys will chime in with good info.
 
Ditch that prop and your buddy will lose. Def. step up to a good SS prop and prob. a 21p depending on your WOT RPM's. I'd venture a guess you should be seeing around 5200rpm +- 300. If you are seeing that much or more, go to a 21p. That boat should get into the low to mid 60's with a proper set-up.
 
chrispallen said:
if you are looking, i have a 22 lazerII that i can send you some pics of..... let me know $150 to your door
Click to expand...

he needs a 21 or a 23... even numbers is outboard hub...:)

depending on the 350 specs... might be better to prop for wot a little under 5000. not because it'll fly apart, but because that's more than likely where peak horsepower is with a factory cam in it and where it'll be the fastest... (not knowing the engine specs of course...)
 
wca_tim said:
he needs a 21 or a 23... even numbers is outboard hub...:)

depending on the 350 specs... might be better to prop for wot a little under 5000. not because it'll fly apart, but because that's more than likely where peak horsepower is with a factory cam in it and where it'll be the fastest... (not knowing the engine specs of course...)
Click to expand...

Well, he did say mildly cammed and .040 over, he should be around or just over 5k rpm. Stock 454 mag is capable of 5k rpm. But def. lose the cheap prop. IMHO, no checkmate i/o should ever use an aluminum prop, unless you just fragged your good SS and need a quick spare to change out. :lol:
 
winter said:
Well, he did say mildly cammed and .040 over, he should be around or just over 5k rpm. Stock 454 mag is capable of 5k rpm. But def. lose the cheap prop. IMHO, no checkmate i/o should ever use an aluminum prop, unless you just fragged your good SS and need a quick spare to change out. :lol:
Click to expand...

I can agree with that
 
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