Input on 353 Speed/RPM's

Sneaky Fast · 07-25-2008, 04:31 PM

Hello,
Purchased a 353 with 502's and stelling extension boxes. Running 28 4-blade merc bravo props. At full throttle I am only seeing about 4400 RPM and it doesnt change hardly at all with agressive trimming. I have standard Bravo lowers and am wondering if its my X-Dimension more than switching to 26" props... Thoughts????

Magicfloat · 07-25-2008, 04:48 PM

28's would have been shipped with the boat. I assume 1.50 gears? Di d it come from Formula with the Stellings.or added later?

Sneaky Fast · 07-30-2008, 11:48 PM

Magic,
Sorry for the late reply, been away on business. The stellings came from the factory on original order. We are thinking maybe shorty lowers would help alot. Seems like the X dimension is too low with the boxes and standard lowers. Thoughts??

axapowell · 07-31-2008, 10:57 AM

This spring I installed IMCO boxes with -2 Sportmaster lower. After testing several props, I have spaced the drives back down 1/2" because of excessive slip numbers. So in theory, I'm 1 1/2" higher. Formula changed the X in 2002. They raised it 1/2" from that production year on. With the Stellings, you can adjust up to an inch higher (I think it's an inch). You should pull an inspection cover and see where you are at first before spending $$$ on lowers. I wouldn't go more than 1" higher, but it really does depend on the boat. Spacers are expensive, but so are lowers. If you go to high, plan on spending the $$ on spacers. Just some thoughts, hope this helps!

Dave

Sneaky Fast · 07-31-2008, 10:12 PM

Thanks Dave I'll take any input that I can get!!