What to set WOT timing to

**NDIceMan72** · 06-17-2022, 02:48 PM

Hey all. I’ve been doing some improvements to my 1991 135 black max. Deleted oil injection and went to premix in the tank at 50:1. Installed ccms reeds and now I just removed the idle stabilizer box and need to set the timing. I’ve heard 21, 23, and 25 degrees at WOT. What’s the verdict and what should I set it to? It’s on my 1990 Lund tyee 1850 and I run straight 87 octane with no ethanol for fuel. Also is 50:1 the best ratio to run? Thanks guys, I appreciate it!

**rgsauger** · 06-18-2022, 07:56 AM

That’s a sweet little motor! Sounds like you have made the right mods for it to last a long time. The manual states 19 degrees at WOT. With you running 87 fuel, I would not push it on timing. Any incremental gain is not worth the risk in my opinion.

http://www.hedges-uk.com/boat/Merc/o...nd%20Above.pdf

**merc1250bayliner** · 06-18-2022, 10:40 AM

But don't the modules advance timing to 25? So without them there you wouldn't get the timing advance past 19?

**NDIceMan72** · 06-18-2022, 06:03 PM

I never adjusted it yesterday, checked it and it was at 21 already. So I’ll run it and see what happens

**Jim Speros** · 06-22-2022, 07:52 PM

Originally Posted by rgsauger

With you running 87 fuel, I would not push it on timing. Any incremental gain is not worth the risk in my opinion.

I agree.

21 is plenty of timing. Everybody should take into account how much the quality of fuel has diminished in the last 20 years.
I won't ever recommend running 87.

**NDIceMan72** · 06-29-2022, 07:00 AM

So I had it out last week and got the jack plate height set. She’s running really well. I’m getting 42 mph WOT all trimmed up, but I’m only getting 5100 rpms. So a different prop is in order. Currently running a Stiletto 14-1/4x19. Any prop suggestions? If I can get more speed on the top end that would be fine, but not necessary. I just want to get the rpms where they need to be, which is 5600 for this motor. Thanks guys

**rgsauger** · 06-29-2022, 11:48 PM

When you say you got the jack plate set, how did you know when you were high enough? Did you lose water pressure?

**NDIceMan72** · 06-30-2022, 12:10 AM

Originally Posted by rgsauger

When you say you got the jack plate set, how did you know when you were high enough? Did you lose water pressure?

Yes, water pressure started to fall off.

**rgsauger** · 06-30-2022, 08:09 AM

Was it running better and better as you raised it until the water pressure started dropping? In other words, would higher have been better if you still had PSI? I ask because you can plug the two top holes in your water intakes and add the little stainless scoops on the sides of your intakes and get a lot more water in there if the motor still needs to come up a bit. If it's buried, you won't see bigger #'s on top because of water resistance on the lower. Before I did the low water pickup cone, I was playing with the little scoops. They actually made a huge difference. You can tap the upper two holes on each side 5/16" and then use loctite and Allen flush plugs to seal the top two.

**Jim Speros** · 06-30-2022, 08:26 AM

I have found if the boat runs less then 50 mph most of the prop will need to be in the water. Raise engine just enough to got an inch or two of the top of the blade to clear water. That is provided you have a high rake prop that will appreciate a little ventilation. Get the R's up to 5800 and find a prop that responds to trim well and carries the bow.

**NDIceMan72** · 06-30-2022, 08:41 AM

Originally Posted by rgsauger

Was it running better and better as you raised it until the water pressure started dropping? In other words, would higher have been better if you still had PSI? I ask because you can plug the two top holes in your water intakes and add the little stainless scoops on the sides of your intakes and get a lot more water in there if the motor still needs to come up a bit. If it's buried, you won't see bigger #'s on top because of water resistance on the lower. Before I did the low water pickup cone, I was playing with the little scoops. They actually made a huge difference. You can tap the upper two holes on each side 5/16" and then use loctite and Allen flush plugs to seal the top two.

It did not run better up where the water psi fell off. Ended up coming back down a 1/2” and that seems to be the sweet spot.

**OnPad** · 06-30-2022, 10:28 PM

I'll get beat up by RG for this, but try and find a laser prop to try, in odd pitch size. Or maybe a old quicksilver round ear. Both props have smaller diameter than what your currently running, and should free up the engine.

I also run my ignition timing higher on my engines, but in a different application with less load. For daily reliability you got good advice in above posts.

To answer mr.bayliners question. Yes when you remove the advance module on a 200hp and Promax, you lose that capability. You would have to know if your module had that function to begin with, as it's not real clear in the service manual on the lower horsepower models, and they have had some different timing modules over the years.

**rgsauger** · 07-01-2022, 11:42 PM

Hey, if a Laser II prop works, then go for it. I just have not personally ever had any form of success from one. Maybe my setups were all wrong, maybe not. It’s always enlightening to play with buddies’ props.

**NDIceMan72** · 07-03-2022, 10:54 AM

I found another Stiletto prop, same diameter just a 17 pitch vs the 19 pitch I have on the boat. Picked it up dirt cheap on eBay and it looks like new. We will see if this helps out, thanks guys for all the advice!