5200 rpm from 302

The 78 tique is hitting 45 mph GPS at about 5200 rpm. Noticed this last night after a tuneup. I only do it for 30 seconds or so. Should I be not letting it get above 4400 rpm like the owners manual says? Just got a boom this week and am going to start footing. I am 6'6" 250 lbs so my barefoot speed is about 45. Wondering if I am overdoing it or maybe my tachometer is off. Thanks for input. Will test more this weekend but I think my speed at 4400 is about 41 or so.
Jeff

I would verify on a good shop tach, the in-dash gauges are famously inaccurate. My tach in my 94 is at least 200 RPM off what the PerfectPass says at WOT.

5200 won't hurt anything if it is actually revving that high, but you might pick up a bit more top end with a prop with more pitch since it'll put you back in the powerband a few hundred RPM lower. Any idea what prop is on there now?

TRBenj wrote: Pete, you've always reporte 4200 with your 12x14 Oj. If it's creeped up over the years you may want to break out the shop tach too! .

Tim,
Yes, I did report the 4200 when I first got the Tique. Then I did break out the shop tach!

Jeff,
As mentioned, the dash tachs can be off pretty much. Plus, they have a tendency to jump around making them hard to get a good reading.

Should have a prop on there Tim that's not as old as his points or impeller,remember not that long ago his son rearranged the underwater gear   

Then the shop tach is lying, or your prop is tired/improperly rebuilt... A 12x14 Oj should under turn by 300-400rpm on that hull. I assume you're running the more typical 46-47mph vs the atypical 50-52? The latter would indicate a pretty fast hull and/or 250-275hp from that 302.

Hollywood wrote: If your tach needle is bouncing you've got issues.

Yes, it's called rough water and or hull porpoising.   

Should be a 12x14, Pete... 12x13 is ideal but you always claimed you wanted to lower the revs for all the wot runs your family likes to do when you're not around.

13" diameter is too big for that hull- hull clearance is too tight, especially on an oj or federal. Acmes aren't so bad with all their aft rake, a 12.5" diam has as much clearance as a 12" hand finished. I believe you tried a 540 acme (13x12) and took it right off because it buzzed.

My 78 Ski Nautique would run over 50 MPH with a 13 x14 3 blade and tach up to 5,200 RPM regularly. The only thing not stock was the heads, I had a set of 289 HP heads, smaller chambers bumped the compression and they had extensive porting and larger valves. They did add quite a bit of pop to that 351W engine. Sold it with 1,500 hours on it so the RPM never hurt it any it still ran great.
On a good day it seems that old boat would run 52+ MPH. Used to tick off the owner of West Coast Correct Craft. We skied together many times and we would launch at the same time and have to cross the lake to get to the river for the smooth water. It was about a 10 minute run across.   He could not stay with me when I opened it up. His boat was equipped with a 454. He could pull stumps for sure but I had him on top speed.   I don't think I ever shared the fact I was running the 13x14 prop.

With a Chevy 350 in my Tique it 's pretty fast and around 50 ish
it will porpous and the speed will drop off. Feathering the throttle
and driving through it could take a 1/4 mile.

There is a trade off in the bottom end power with a 13x14. Mine was still strong before and after adding the heads. I had to replace it twice in 10 years and performance remained the same so the prop was not a special tweak. If you ski a course regularly certainly pass on the 13x14.

It takes alot of horsepower to turn a 13 14 at 5200rpms...like near 400...so maybe some #'s aren't quite remembered right.

Ha! I wasn't really going to look for the 14". my first priority is a new cnc for the marauder. its running an old federal.

I know the 302 will turn up past 4400, But the farther you go past the limit the more likely you are to stretch a rod bolt. If the motor is from the mid 80's or later I would be very careful. May run a day, week, month or forever.

Frank