timeing 2.5 200 carb

[redsnapper386]

guys what would be safe max timeing and pick up for my motor no black box 1993 2.5 carbs 200 hp bored 15 over fishing motor stock carbs bobs x-aust tuner thanks

[rgsauger]

23 is usually considered safe on premium gas. I think it’s 19 on 87 octane. Someone else will confirm
Have you ditched the the oil pump and started premixing yet? 50:1 if you’re not over 6,000 rpm.

[rgsauger]

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

[mach351]

Depends on compression. 25* at 145-150psi is pushing it on 93 octane. Stock 115-120psi and 19* you should be fine on 87 all day. In between gotta pick the right spot.

[redsnapper386]

thanks guys compression test next

[MrG]

If you use opti max as premix it has octane boost in it I run it 40:1 with 87 and 25 deg to 7k 140 psi Comp with 115 deg TStats up 2 on main jets/ NGK BUHW plugs

[redsnapper386]

If you use opti max as premix it has octane boost in it I run it 40:1 with 87 and 25 deg to 7k 140 psi Comp with 115 deg TStats up 2 on main jets/ NGK BUHW plugs

guys i checked timeing this is after rebuild 15 over wsm parts 1,3,5 =148 psi 2, 4,6 = 140 psi so ill go with 25 max timeing and try opti max pre mix im at 66 main jets seems ok thanks guys good stuff

[rgsauger]

Ummmmmmm...Personally...I'd start at 23 degrees and read your plugs to see what's up before going to 25 degrees. You just spent a bunch of money on your motor and your compression is far from stock. It's your motor and your business but the last thing you want to do is melt a new motor when you're running 15 miles at 5K (or more) RPM from one end of the lake to the other. The difference between 23 and 25 on a fishing motor is negligible on performance

.066 mains??? that sounds SMALL to me. I would have expected .080-.084 or so. What carbs do you have?

Post your serial number and we can drill down on what Merc calls for it. You want to make CERTAIN that you have PLENTY of fuel for this beast. Best to start big and walk down as your plugs tell the story.

Have you broken it in yet? Good to go closer to 32:1 or so on oil for the first 5 hours. Then 40:1 for the next 5 hours.

[mach351]

66 is stock for WHM series 2.5 200 carbs

[redsnapper386]

66 is stock for WHM series 2.5 200 carbs

wmh-33 carbs will be useing shell 93 with nitrox most of time motor is broke in now was useing 32-1 merc syn will go to 40-1 as advised also to add this to post i am running twinns 2.5 s on a 24 ft off shore my other block is in machine shop it will be the same thanks again and i appreciate all help and advice

[Merc 2.5]

I run 25* on the highest cyl (check all 6) then the rest is 25 or below 24 ,23
93 octane, 150lbs comp. 1000+ lbs boat , but I check my junk alot , 23 is safe but if u set #1 to 23. I'll bout guarantee u will have atleast 1 cyl at 25* possibly 26