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Discussion Starter · #1 ·
Ok so let me start off with the bad technical info because I know how important it is and I know every one is going to ask these things but unfortunately I don't know these things yet only had the boat a few months, I have a 1975 Tahiti 17 foot it has a fresh 396 runs great, supposed to be running 9:1 with a mild cam and a 750 cfm quick fuel slayer carb with vac secondaries and fresh berk 12jc that's stock (I don't know what impeller or rpm I'm turning). I'm running what seems to be fairly wet and only pulls 47mph on GPS. I'm also at 5,400 feet above sea level. I've done a bunch of research and from what I find (not much being its a 396 and the guy said it dynoed at about 367 hp) my guess would be I should be closer to 60 +/- a couple? does that sound correct or should it only be doing 47? And like I said I'm sorry I don't have all the critical info you guys need to really know if I should be running a little faster I was more looking to see if any one could just kinda guess from they're personal experience. Also would a place diverter help at all gain anything other than being abel to fight fires and look good? Thank you guys very much!
 

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Discussion Starter · #3 ·
If the boat feels super wet then a diverter is.going to be the best investment u can make.for additional speed and handling

Well from a picture taken from another boat the hull is pushing water out a little further tawords the front than half way so from other pics of boats they look like the intake for the pump is barely touching the water??
 

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Well from a picture taken from another boat the hull is pushing water out a little further tawords the front than half way so from other pics of boats they look like the intake for the pump is barely touching the water??

That would be due to a little something called HP and a light boat... Not "or"...

I all honesty, that small of a boat should really be powered by a pissed off small block.

The low compression 396 is not a horrible start, but wont be a rocket ship, the short hull is not helping your cause either...

Does your hull have the scalloped transom?
 

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Discussion Starter · #5 ·
I all honesty, that small of a boat should really be powered by a pissed off small block.

The low compression 396 is not a horrible start, but wont be a rocket ship, the short hull is not helping your cause either...

Does your hull have the scalloped transom?


I'm not to greedy :) I'm not looking for a rocket ship necessarily I just want to be around the 60-65 mph mark until I can get a different hull and more funds. And what do you mean "scaloped"?
 

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Discussion Starter · #6 ·
And I'm sorry I guess I should word things differently because I understand that a light high hp fast boat will barely touch the water, I was more or less trying to find out what you folks consider "wet"? Half a hull touching? around the front of the engine area touching? Or anything other than barely touching at the intake?
 

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Your set up is gonna run maybe 50 mph which is good. The JC pump is not a split bowl so you don't have as many options as a JB or JG. Do you really want to spend the money to go 60-65? You're probably looking at a couple grand to get it done. Do you work on your boat yourself? Can save lots of cash on labor. Pictures of your pump and boat would help.
 

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I had an 18 Tahiti with a stock 455 olds. Mild cam. This is in NM where most of the lakes are 4600 and above. With the super dry air the density altitude was much higher. Low compression, thin air, heavy boat. Hard to make fast. I ran about 50-55 at best at 4300 rpm. My new18' gullwing which is an air trapping hull runs 70. That's a lighter boat than your Tahiti. 440hp at altitude 468 BBC. 10:1 moderate cam pushing 5250 rpm. This is also with a diverter and ride plate and loader and shoe. It's gonna take some $$$ to try to get yours to 60-65 at such altitudes. I'll say the same thing to you as was said to me when I was wanting more speed from my old boat.
"How much you willing to spend? Be happy with what you've got or buy a different (lighter, full stringer, more capable) hull so you will be happy with the money your gonna spend." Good luck
 
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