Difference in performance w/ trim tabs

[FreeBeeTony]

How much of a difference could one expect after installing trim tabs? I have a friend in the boating business and he gave me an entire trim-tab set-up (Boat Levelers?). The boat is a '78 20' Grady White w/ 165 IL6 Mercruiser. I have only had the boat for 1 season, I am turning a 15" pitch prop at the moment.

 

[POINTER94]

Re: Difference in performance w/ trim tabs

Depends on what you are defineing as performance. You could plane out faster, maintain plane at lower speeds, and allow you to adjust the boats attitude while on plane. I wouldn't look for any increase in speed in your boat.

 

[POINTER94]

Re: Difference in performance w/ trim tabs

OOpps,<br /><br />No don't put those on your boat, it could be very dangerous... Just send them or your friend to my house.. I will see that they are properly taken care of!!!<br /><br />Free Trim Tabs, very cool...

 

[DJ]

Re: Difference in performance w/ trim tabs

FreeBeeTony,<br /><br />That is a heavy boat you have there.<br /><br />The 165 is a good performer, but it's no speed demon, that's for sure.<br /><br />I think the tabs will amaze you. Put em' on.

 

[Maximerc]

Re: Difference in performance w/ trim tabs

Self adjusting tabs do a great job, things I have noticed<br />1. boat comes out of water much flatter, nice to see where you are going!<br />2.My "hop"is gone unless I load every one in hte back of the boat , but I have not tried to increase the pressure on them yet.<br />3. fuel mileage is up a bit <br />4.Absolutly no messing with the engine trim .. my boat was horrid .. made me feel like I had never run a boat before.. been running outboards since I was 12.<br />5. At low speed the wig wag at no wake speed is nearly gone !!<br />6. I do not see a loss in speed<br />7. I do see a lot more stability at cruise speed.<br /><br />YEAAA BTW home built.....

 

[snapperbait]

Re: Difference in performance w/ trim tabs

I dunno about performance, fuel economy, and all that stuff.... But, they are well worth having just to be able to control the boats attitude... <br /><br />Leveling out the boat with an un-even load, up on plane faster, ability to really put the bow down and smooth out the ride when it gets choppy.... stuff like that..

 

[FreeBeeTony]

Re: Difference in performance w/ trim tabs

As I stated in my original post, I am running a 15"P prop. This is due to the fact that it seemed like the boat had a hard time getting "out of the hole". Will the trim tabs enable me to run more of a pitch?

 

[DJ]

Re: Difference in performance w/ trim tabs

FreeBeeTony,<br /><br />The tabs will help you get on plane quicker, no doubt.<br /><br />THe pitch of your prop is relative to engine RPM's. Will that change, hard to say. Tabs are always a good idea.

 

[Vector501]

Re: Difference in performance w/ trim tabs

To plane out better does that mean that the trim tabs are pushed down or raised? I'm new to trim tabs.

 

[DJ]

Re: Difference in performance w/ trim tabs

Vector,<br /><br />Down.

 

[Vector501]

Re: Difference in performance w/ trim tabs

Thanks

 

[Ralph 123]

Re: Difference in performance w/ trim tabs

Vector, just visit the mfg website to make sure you have the proper plate size and for mounting instructions.

 

[Vector501]

Re: Difference in performance w/ trim tabs

Well I can't find that boat anywhere...it has the plates on there already, it came with them. The papers for the boat say it's a Carr TL model and I can't find it anywhere...

 

[snapperbait]

Re: Difference in performance w/ trim tabs

Vector.. try these.. Your trim tabs are bound to be one of these..<br /> http://www.bennetttrimtabs.com/ <br /><br /> http://www.trimmaster.net/ <br /><br /> http://www.insta-trim.com/main.html

 

[Vector501]

Re: Difference in performance w/ trim tabs

they look like the trim master.......here's the boat for what it's worth.

 

[daveswaves]

Re: Difference in performance w/ trim tabs

Free Bee Tony, I agree with Djohns19, put em on, you will love them. I run a similar boat to yours and added trim tabs two years ago. That chevy 6 is a workhorse but not too speedy, 4200 RPM is the most you should push it. They perform well at 4000. The trim tabs won,t make you go faster, but they will let you go slower with "grace". I run a 19P on my 165 and can back the throttle off to 2500 rpm and cruise at 25 mph, on plane, trimmed out nicely, very smoooooth. Top end with my 3500# boat, 20 foot cuddy, 37 mph at 4000 rpm with 19 p. I boat on Lake Erie, lots of challenging waves, trim tabs are great. I also run boat levelers. Great product.

 

[FreeBeeTony]

Re: Difference in performance w/ trim tabs

daveswaves, what outdrive are you running. is it a 1.65:1? I was only able to get 3200 rpm's with the IL6 , 1.65:1 outdrive and a 19" pitch prop. I had to go down to a 15" to get close to 4000.

 

[daveswaves]

Re: Difference in performance w/ trim tabs

Hey Tony, yup it is the same as yours, 1.65:1. When I first put the 19 P on I had similar results and I took it off and went back to my trusty 15P. In my case it was dirt/corrosion in the carb from a new carb kit that I had put in, the accelerator pump spring corroded!! The corrosion plugged the high speed jets just enough to limit my top end with the bigger prop. I pulled the carb again, cleaned it , and it worked fine. One thing I did do with the 19P prop on is re time the engine as I had a slight ping at wot with the 19P, I backed off on the timing approx 2deg, my rpm came up and the engine sounded "right" It was not untill I retimed it that I realised it had always been a little "tight" or advanced.

 

[FreeBeeTony]

Re: Difference in performance w/ trim tabs

Dave......I rebuilt the carb last year (when I rebuilt the entire engine)......can you be more specific about what you found and what you did to the carb? I would be interested to find out...... was the corrosion under the accelerator spring? The engine I rebuilt had been sitting for sometime, I thought I had cleaned it thoughly nut maybe I missed something. I also had trouble timing it, the timing marks in the timing cover are not very plain to see, maybe my timing is too far advanced? How can I tell if its too far advanced? Any tips would be appreciated!

 

[daveswaves]

Re: Difference in performance w/ trim tabs

Sure Tony, no problem. You are correct, the accelerator pump spring itself corroded and left a fine white powder, almost crystaline, in the bottom of the pump body. This powder found its way into the carb jets. This was only after 10 hours of running on the rebuilt carb. The zinc plating on the spring reacted with something in the gas and deposited in the carb. I cleaned the carb again (put the now clean/unplated pump spring back in) I have run with no problem since.<br />The timing I resorted to an old method. Remember, the 6 deg that you set at idle is only part of the timing, at WOT the advance springs under the distributor rotor add considerable advance. In my case, and possibly in yours, the TOTAL timing was simply too much for the 19P prop set up.<br />This is how I tweaked mine: warmed the engine up by running the boat and then put a vacuum gauge directly on the intake manifold. At idle you should have close to 20 inches of vacuum and the gauge should be very steady, the needle should not be bouncing. I then loosened the distributor hold down bolt and rotated the distributor slightly untill the vacuum dropped off to around 15 inches. At this point the engine would be way retarded, the needle may be wavering a bit and the engine rpm will have dropped, the engine may "lope" a little. Then slowly rotate the distributor the other direction and watch the vacuum guage needle very closely. Very slowly advance the timing untill the needle on the guage is as high as you can get it. You are looking for a "sweet spot" where the vacuum is high but not so high that the engine "struggles" and the vacuum wavers.<br />When you have found that spot just knock the timing back a wee bit so that the vacuum gauge drops by 1". So if your "sweet spot" produced 20" of vacuum at idle retard it a bit so that you have 19".<br />At this point your total advance should be just under what your engine can tolerate. Take it for a run, it will sound totally different than you are used to. If you got it right it might even sound a little "snarly".<br />You may have to adjust your carb low speed jets to accomodate the heavier pitch prop and the new timing setting to get a smooth idle.