Gearing question

[mickeyfinn]

OK. Been crashing in the sandbar too much. Not getting much done on the boat so it is time to refocus with a "real boating" question.
I am putting together a 402 chevy. Nothing special it is bored .60 over with a .550 cam and 10.5 to one pistons. I have a 1972 hondo 18 footer. What kind of gears and prop should I be using to get a good top end speed. I am hoping for at least 65 to 70, and of course if more is available that is great too.

[GofastRacer]

A lot depends on what kind of RPM's you plan to run. My guess would be 15's with a 11 1/2x15 to start off with and go from there. If you can, try and borrow different gears and props before you dump money to find out it's the wrong combination!..Just my .02.... :rolleyes:

[V-Drive Tom]

Mickyfinn, I have the same engine in my sanger flat. (1975,A little bigger and heavier boat) If you want it to be quick out of the hole, you don't want more than a 12% gear. 15% will work OK but your engine doesn't make enough power to pull that gear with a good propeller. A 15 pitch 2-blade will work good and be less expensive than a 16.
If you want some propeller help, I will gaurentee we get your boat runnig as good as it can. TOM.. :) PS. 75 to 80 MPH should not be a problem.

[mickeyfinn]

The engine should be turning around 5500 to 6000 rpm's. I haven't had the boat in the water for the last few years, (had a few kids and money been tight) but in the past I have found that in addition to short burst I occasionally will run at close to WOT for a 15 or 20 minute run up the lake. I am in the Atlanta Georgia area so not many V-drivers around so playing with gears and props probably isn't a viable option. May just have to depend on everyone here for good advice. If advice isn't right then what the hell....its only money right?????????
Let me know if the rpm makes a different in what you have said so far.

[Beautiful Noise]

I agree with the Guy's above I'd say with 12's or 15's you'd be fine,With a 11.5 x 15 Prop.Just my .02 worth :)
Steve

[Fired Up]

I'm running pretty much the same set up also, just a little bigger motor (454). Same compression and a single 850. With 15% and an 11 1/8 x 15 1/2 two blade I'm turning 5700 rpm's at about 80 mph, 12 secs. in the quarter. I'll be trying some different gears (12% )and prop at the next race to see what helps a little with the rpm.

[Ratacole]

Mickey Finn, just like you I didn't know & still don't know crap about gears & props. I called V-Drive Tom at Menkens V-Drives & told him what I wanted to do with the boat (speed, RPM ect...), I liked my speed but didn't like beating the crap out of my motor. I'll be God Damm if he didn't put me within 2-3MPH & 250 RPM of my goal. The problem is he also gave me a formula to ball-park the speed of a boat with RPM, gear & prop. Now I need more power because I want my RPM back up there :D
[ May 12, 2003, 01:07 PM: Message edited by: Ratacole ]

[CircleJerk]

Easy there! You're talking about the same mill that Blonde won two championships with! We ran 18s and pulled 5800 with a ll1/4X15 menkins prop. We could have used 15s but I was too lazy to change gears AND catch ____ when she went slower. Your heads can really wake up a 402, keep the intake small and install 1.88 exhaust valves with that small cam and run small {2"}headers pipes. Some rare 402 heads have a weird combustion chamber that unshrouds the valve to a semi-open style. #6272292 is this 1971 head and is rather rare with a lot of potential. With this combo, I have beaten many 454s! smile_sp

[superdave013]

I've got 12% gears in 10 and 12 degree.

[superdave013]

Ratacole:
Mickey Finn, just like you I didn't know & still don't know crap about gears & props. I called V-Drive Tom at Menkens V-Drives & told him what I wanted to do with the boat (speed, RPM ect...), I liked my speed but didn't like beating the crap out of my motor. I'll be God Damm if he didn't put me within 2-3MPH & 250 RPM of my goal. The problem is he also gave me a formula to ball-park the speed of a boat with RPM, gear & prop. Now I want my RPM back :D You boat looked like it was geared pretty good to me for what you're doing with it. Maybe try some 25's sometime but don't gear it up anymore.
It was sweet seeing you spank that hydro!