Stock timing was right around 35 degrees if I remember right, boost from Merc was at 4.5 - 5 lbs. With the chillers and smaller puley I was at 7 -7.5 lbs of boost, what you need to remember here is that the higher boost intercooled is in fact easier on the engine than the stock boost without it. I had the CMI E-Tops, ran the stock timing, with the carbs just a little on the fat side on the top end and they ran like champs, never a single problem. I remember reading an article on supercharged engines in Hot Rod magazine years ago where they stated the most reliable factory SC package ever marketed was the Merc HP 525 SC.

I don't think lowering the timing is such a great idea. My boats previous owner did it and the exhaust valves were done at around 150 hours. A stock timing curve has a lot of timing but it comes in late, like stated above.

30 or 32!!!??? Im currently running it at the stock 13 degrees. Please do educate me on this one!

My Bad. Yall must be talkin about WOT timing.

Those are pretty good numbers in that boat. Unless you have a screwed up prop, I seriously doubt you will get 4 mph by cutting on the wheel. And yes, I have some pretty good experience with a dialed in single engine.

If you want you can blow a few grand on a prop and exhaust for that extra mph or so. Bottom line, you are running good numbers and it will take some more power to get 80.

Don't get me wrong, a labbed prop has its place but big singles like power.

I run WELL over 80 in a single screw and have been fooling with them for quite some time.

I switched from the stock Merc Gils to CMI's and gained ZERO on the top end. Actually, Merc switched to CMI's the last year or two that they made 525SC's.

I ran just shy of 8# of boost for almost 300hrs without a chiller . Timing was set at the stock 35*. I only increased the carb jetting when I put in a bigger cam(731).
Like all Merc stuff, the stock jetting is set up on the rich side with #98 jets on all around and 6.5 PV's on both sides.

13* at idle with a 22* module that made full advance at 4250rpms for a 35* total. Stock boost is 2:1 overdriven for 5.5#.

what I do not understand, if you talk to the blower guys at weiand (who made the blower setup on a 525) or read the install manual, they recomend a max timing of 26-28 deg...whats up with this....I have always found backing the timing down under boost works best...Rob

Blower engines like all the timing they can get and as long as its not having detonation issues, its fine. The 7.5:1 static comp ratio in the 525SC allows you run more timing and boost without having to worry about detonation.

This little cutie last summer went 95 on my boat after screwing me once:drink: