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New guy 500 Cad. gearbox/prop question

S

scott wheeler

Well-known member
I am new to airboating (6 months). Have a weekend place on Taylor Creek Okeechobee at a camp ground. I owne a 14ftx7 Stump Jumper (fibre glass), direct drive 500 Cad, SS cage. Currently I am using a 72x36 wood paddle prop. The motor will run 2200 rpm on the trailor, and at least 3000 rpm while running with 2 men on board (280 pounds ea.). The motor is stock. I want to put a 209 gear box, and a 2 blade super wide blade 78 or 80 inches long. One of these days I will have my motor built. Wife, new hull, gear box, and prop, is about all I want to spend at this time (airboating is a sickness). Being 60 yrs old I dont care about going 100 mph, but also I dont want to get stuck again. A 60 year old fat man aint a pretty sight trying to push and airboat. What do you guys think about this set up to start with. I use the boat to fish and ride the lake. I know about rpm with a stock Cad. I would like to meet some people in Okeechobee to occasionally ride with also.

I don't want to be long winded but I need to say that this forum is the greatest thing since sliced bread. I can't get over the vast knowledge you folks have. Man it's been a gift to me. Thanks. Scott
 
mr. wheeler i ran a 2.09-1 gearbox and the 2 blade superwide on my caddy and it is not a stock build.and my combonation did well but i would suggest the 2.38 with that prop it will make all the difference in the world.and even after you rebuild it you can just add more pitch to govern down the engine rpm.
 
plumcrazy":386wikof said:
or 2to1 with 3 blade power plus is bad ass on a caddy been there done it
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also a good choice; i ran a 1.9-1 with a 3 blade it also was a good combo.
i never seen plums old boat run but i heard he could tow another heavy boat on plain.
 
Man please don't call me Mr. Wheeler. To be truithful I've been called Bubba most of my life. Scott or Bubba would be great. The reason I was going with a 209 is because of the rpm. Wouldn't 238 make my motor turn more rpm to get to the 1500 or so rpm a super wide needs to turn. How many rpm would you have to run on a stock Cad to reach 1500rpm on a super wide. What have you done to your motor. Scott
 
scott wheeler":ecgcqnul said:
. The reason I was going with a 209 is because of the rpm. Wouldn't 238 make my motor turn more rpm to get to the 1500 or so rpm a super wide needs to turn. How many rpm would you have to run on a stock Cad to reach 1500rpm on a super wide. What have you done to your motor. Scott
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bubba with a 2.38 to reach 1500 prop rpm you would turn your motor 3570 engine rpm.you could safly turn that stock caddy to 4000 but safety wise i would say no more than 3800rpm.until upgrade of valve train.
 
scott wheeler":2bqbm9m4 said:
I am new to airboating (6 months). Have a weekend place on Taylor Creek Okeechobee at a camp ground. I owne a 14ftx7 Stump Jumper (fibre glass), direct drive 500 Cad, SS cage. Currently I am using a 72x36 wood paddle prop. The motor will run 2200 rpm on the trailor, and at least 3000 rpm while running with 2 men on board (280 pounds ea.). The motor is stock. I want to put a 209 gear box, and a 2 blade super wide blade 78 or 80 inches long. One of these days I will have my motor built. Wife, new hull, gear box, and prop, is about all I want to spend at this time (airboating is a sickness). Being 60 yrs old I dont care about going 100 mph, but also I dont want to get stuck again. A 60 year old fat man aint a pretty sight trying to push and airboat. What do you guys think about this set up to start with. I use the boat to fish and ride the lake. I know about rpm with a stock Cad. I would like to meet some people in Okeechobee to occasionally ride with also.

I don't want to be long winded but I need to say that this forum is the greatest thing since sliced bread. I can't get over the vast knowledge you folks have. Man it's been a gift to me. Thanks. Scott
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I have run Cadillacs for years now and the 2.3 reduction is the ticket for the motor. Until you change the valve train on that motor I would not suggest going past a 1.5 reduction and even then I would carry a box with you in case you blow parts out of the top end. Also your motor should be turning way more RPMs then that with that prop. I ran a 72x44 FAP paddle prop on mine and I got 3100rpm. Make sure you are getting a full 32 degrees advance by 2100rpm and you have at least 10 degrees at idle. Do not use any vacum advance at all.
 
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