Max timing on merc v135?

[bryanwess2000]

I finally ready to time my motor. Idle stabilizer has been removed and I want
to set timing safely. The manual and flywheel cover says 19* at cranking
speed which is 17* above 5000rpm so I'm guessing the ide stabilizer retards
timing above 5000rpm. The manual does not mention this only timing advance
at idle when shifting into gear.

So what is safe timing on todays gas without an idle stabilizer. I"ve seen
posts on S&F forum where people are running 25-26*. I'm not that brave.

 

[j_martin]

Re: Max timing on merc v135?

I finally ready to time my motor. Idle stabilizer has been removed and I want
to set timing safely. The manual and flywheel cover says 19* at cranking
speed which is 17* above 5000rpm so I'm guessing the ide stabilizer retards
timing above 5000rpm. The manual does not mention this only timing advance
at idle when shifting into gear.

So what is safe timing on todays gas without an idle stabilizer. I"ve seen
posts on S&F forum where people are running 25-26*. I'm not that brave.

The timing module advances it 4 degrees at 5000 rpm, then retards it 6 degrees at 5500 rpm.

Set yer max timing at 23 degrees.

I've experimented a bit with further advance on an XR4, and I don't see enough gain to justify the risk. You can hear a slight change in the exhaust note, but not feel it.

hope it helps
John

 

[sschefer]

Re: Max timing on merc v135?

First, congrats on stepping up and dumping that advance module/idle stabalizer.

I've got two fairly new 40amp flywheels and they both say to set the Max adv to 21 without the advance module and 19 with it. Now if that's not an admission of guilt I don't know what is.

Like j_martin say's 23 seems safe enough and will get you a nice strong pull all the way from the bottom. These engines run rich with the tiny carb throats and I've pushed mine up to 25 without any probs. I've got mine set to 23 now and it seems to like it.

You may find it hard to get 23 degrees without adjusting the trigger linkage. I think when my 91/135 was set to 7/8" as per the manual I could only get 21 and then I hit the end of the slot in the bearing cap. I reset it to 1/2 and got to 25.

Just remember, the further out you go the shorter the life of your engine. When you hear folks running big numbers they're usually looking for maximum performance and not longevity.

 

[j_martin]

Re: Max timing on merc v135?

First, congrats on stepping up and dumping that advance module/idle stabalizer.

I've got two fairly new 40amp flywheels and they both say to set the Max adv to 21 without the advance module and 19 with it. Now if that's not an admission of guilt I don't know what is.

Like j_martin say's 23 seems safe enough and will get you a nice strong pull all the way from the bottom. These engines run rich with the tiny carb throats and I've pushed mine up to 25 without any probs. I've got mine set to 23 now and it seems to like it.

You may find it hard to get 23 degrees without adjusting the trigger linkage. I think when my 91/135 was set to 7/8" as per the manual I could only get 21 and then I hit the end of the slot in the bearing cap. I reset it to 1/2 and got to 25.

Just remember, the further out you go the shorter the life of your engine. When you hear folks running big numbers they're usually looking for maximum performance and not longevity.

I hear ya on the max bit. Had to do a little doctoring on the end cap slot the trigger harness was coming through to get the last degree.

I think Sheffer and I are fussy about, and a bit high on the octane of our fuel. 21* is real safe if you're running bottom dollar pump gas.

john