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Need advice from direct drive gurus

S

swampdonkey

Well-known member
Need advice from direct drive gurus

My Question is ; Is it advisable or neccessary to install a thrust bearing on our 455 olds. I have heard someone mention this and figured I'd ask before we do any damage to our engine. We just purchased our airboat just over one year ago. It had a worn out 350 at the time of purchase so we figured if we're going to change the motor we might as well install something with a little more "torque". So we picked up a 1976 olds and got our engine buddy to go through it from top to bottom. We what to take every precation in order not to damage our BABY!!!. Will the thrust from the prop damage the engine? We are pushing a 8 x 18 airgator, this is a heavy boat and I'm affraid that all that pressure on the bearings could cause them to fail. (Any input would be greatly appreciated)
THANK YOU
SWAMPDONKEY
PS; If one is neccessary could you discribe proper installation.
 
We have run a 455 olds on our 16 x 8 (2000#) boat for over 10 years now with no trouble. We did re-ring the engine and put new bearings in it about 6 years ago but it is a 1972 engine so it was probably due. The bearings weren't bad but they did come with the re-ring kit. I am running a 500 caddy on my 15 x 7 boat and know a lot of people around here running direct drive engines. I haven't heard any of them complain about the bearings. That is a big boat to be running direct drive. If you could swing it, it would be better to go with a 2 to 1 belt box on that 455 and turn a 78" 3 blade power plus. Its what I'd like to do on our olds boat but it takes the $$$.

just my opinion.

Dan
 
Thanks Nebraska for your input.

We have thought about the gear reduction, at the moment we feel that we better keep it simple because we are newbees. The next thing that we will be upgrading will be the prop. Presently we are turning a 72 x 38 woody. I think we will have to be careful not to over spin it with our new torque monster. "LOL" What type of prop would you suggest???, for our 455? Also we are going to be adding more weight to our boat this weekend, we are installing 1/2 polymer. I know what your thinking!!! Why all that weight, but we encounter some rocky steams where we run and we always run in some water and this material actual float so it should sustain itself or even possibly help with boyancy (CROOSING OUR FINGERS ANYWAY). We will be bolting the polymer on and we were thinking of going with 8" spacing with a staggered pattern. Do you think that this would be a tight enough pattern considering the thickness of our material??. LASTLY I AM PROUD TO SAY I JUST BECAME A "SITE SPONSOR" and hope more people support this site. Membership are what keep this site going and we sure would not want to see it disappear. MANY THANKS
SWAMPDONKEY
 
We are running a 74" Sensenich Q blade prop now. We were also running a 72 x 38 paddle prop on it before. The Compsite prop made a world of difference. It pushes much harder and I have been told that the boat is much quieter as well. On the boat it doesn't seem quieter but I will go with what I'm told. If you go with the belt box it really doesn't complicate much. You will be changing the rigging anyway. If you are thinking you will eventually put it on you should do it now and save the effort. Not only will the rigging be different for the reduction unit but you will need a new prop as well. If you are worried about having too much power for a new airboater just remember that just because you have it doesn't mean you have to use it. You should alway save some incase of trouble. That is what I tell everyone I talk to about airboats. The only way to get out of trouble is to power out of it... my wife is a good example of that. When I was teaching her how to drive a boat she was doing great then the boat started getting squirly and she couldn't keep it strait. She let off the gas and we took a wave over the back... if I hadn't grabbed the throttle with my hand we would have been sitting on the bottom. Back on the prop subject I have heard the Powershift Signiture series is good for direct drive as well.

Dan
 
for the poly... we put 1/4 inch on our boat... took two sheets to cover the bottom. We put the bolts 2 inches apart on the edges and the seam and then 4 inches apart in the middle. We have only done one boat though so it might not be necessary to put them that close. My other boat that I have had the poly on it already and it looks like they are the same.
 
If we can tough it out with this prop for now we might consider a gear box and new prop in the next year or so. We use this boat for hunting but might get involved in some water rescue work with it. We are six people in our hunting party and we are also all part of a local volunteer Fire Dept. The great thing about having six owners is when it comes time to pay for any improvement on the boat we divide by six which doesn't hurt the pocket book so hard and we have all have the same goal. ( Thats to have a boat we can be proud of.) As far as the polymer we used Blue Rhino this stuff comes in one peice, our peice was 10 x 19. It's not cheap but at least we won't have any seams to worry about. Has anyone ever used this stuff before and if so would love to hear your thoughts.

Thanks Swampdonkey
 
I would definately not spend money on a prop until you try the boat out loaded. With 6 people and gear you my NEED the reduction on that size boat.
 
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