4mulafastech

I have been reading in the MerCruiser sterndrive manual about these "trim-in limit spacers" that are installed in front of or behind the trim cylinder anchor pin. If these spacers are installed behind (further aft) of the anchor pin it prevents the drive unit from reaching the last few degrees of full trim under. It appears my 292 Fastech has these positioned like this to prevent the drive from being tucked all the way in. According to the manual this is to prevent someone from having the drives tucked too far in at high speed creating too much stern lift and causing the boat to roll on its side.

I would like to move the spacers so the drives will tuck all the way in to help the boat plane out. I only have a few hours behind the wheel and it takes a little time to plane this baby out. I figure it can use all the help I can give it. Does anyone know more about this subject, or made a change like this? How much did it help? I am running twin 6.2's and 28 pitch labbed bravos.

Thanks!

birdog

It probably will help..Just remember never trim in to turn a step bottom!

jpclear

If you are able to achieve negative trim as you are (prop shaft angling up toward the keel) then it is unlikely that you will get on plane much quicker by tucking in further. A prop change would probably do lots more for you. What rpm are you seeing at WOT when trimmed to your best speed? That sounds like an awfull lot of prop. --- Jer

4mulafastech

I only have three hours of seat time in this Formula 292 Fastech and I only opened it up twice. I have seen 69.1 mph GPS at 5100 rpm on sticky, flat water. These are the 320 HP small blocks and 1.65 to 1 Bravo 1 outdrives

Getting on plane is a little difficult since the X dimension is a fairly high. I throttle up to about 3000 rpm and the props are slipping as the boat noses over. I am able to achieve some negative trim as it is. I was thinking by adding a little more negative trim the prop is actually lower in the water which may reduce the slip (?) These are labbed Bravo props and I have heard they tend to slip more when planing out. (I should probably post this in the prop section too )

Thanks for the replies. I am hoping to find another 292 owner or similar that made this change for their input...

RedDog382

I tried this on my 382 with Stellings boxes. Made no difference. See my comments in the Formula section.

jpclear

Ahh; I never considered the drive ratio thing. You might want to contact Julie at Throttle-Up Propellers since I still think you can get closer to what you are after working with props rather than the trim. Only bad thing: It's lots more $ to mess with props, especially when it's X 2. --- Jer