I've been playing around with the timing on the blue machine with my new Snap-On MT480 diesel timing meter.
It uses a luminosity probe in a glowplug hole, and a photoelectric sensor actually sees the combustion. There is an inductive sensor looking for an indentation of the harmonic balancer. Two to readings are compared at the box, and a timing result is displayed.
To ensure a stable reading, one must wait for the needle to settle at least two seconds before loggin it in as accurate.
Here are some of my results:
Round 1:
I went to 3* BTDC @ 1400 RPM. The engine clack is noticabely louder at idle to about 1500. Beyond that, the volume and quality of the clack sounds normal. My coworker's 96 Powersmoke is still ten time louder though.
As predicted, turbo lag increased slightly, and boost levels were down by about 1/2 psi. There was a substantial increase in smoke throughout the rpm range, but cruising EGTs were lower by 50-75 degrees. It also feels like I picked up just a little bit of power; nothing much though.
Round 2:
I turned the timing down to 2* ATDC @ 1300. There is nearly zero black smoke unless you're really hammering down on it. Boost is very responsive throughout the rpm range, but power is down just slightly. All this at the cost of EGTs. They are much higher than desired at around 750* cruising at 60 mph. They rise quickly on any hill too.
Round 3:
It looks like we have a winner here.
I bumped the mark forward to 2* BTDC @ 1300 rpm. There's hardly any smoke, power is good, and turbo lag is almost non-exsistent. I think this is a good setup for an engine like mine - a conservative fuel rate and low pressure injectors like the 6.2 long style.
One thing that was of note:
I tested three different positions one day to find the right one, and though I moved the pump each time, the marks settled to the same place. There is no strong correlation between the position of the timing marks and the timing figure. Depending on how I jiggled the pump, I could get two timing results that had as much as a 5* difference, but at the same physical location according to the timing marks. This just confirms that the factory-provided timing marks are a great ballpark figure for when one replaces their IP, but adjusting based on the "dime method" is hit and miss for tuning.
I'm going to get some highway miles on it, and see if the economy was affected at all.
Next up is getting some new 6.5TD injectors. I figure that the better atomization of fuel will really help out.
I have a running record of my timing adjustments:
http://www.oliverdiesel.com/images/mt480/6.2_Engine_Timing_Figures.xls
It uses a luminosity probe in a glowplug hole, and a photoelectric sensor actually sees the combustion. There is an inductive sensor looking for an indentation of the harmonic balancer. Two to readings are compared at the box, and a timing result is displayed.
To ensure a stable reading, one must wait for the needle to settle at least two seconds before loggin it in as accurate.
Here are some of my results:
Round 1:
I went to 3* BTDC @ 1400 RPM. The engine clack is noticabely louder at idle to about 1500. Beyond that, the volume and quality of the clack sounds normal. My coworker's 96 Powersmoke is still ten time louder though.
As predicted, turbo lag increased slightly, and boost levels were down by about 1/2 psi. There was a substantial increase in smoke throughout the rpm range, but cruising EGTs were lower by 50-75 degrees. It also feels like I picked up just a little bit of power; nothing much though.
Round 2:
I turned the timing down to 2* ATDC @ 1300. There is nearly zero black smoke unless you're really hammering down on it. Boost is very responsive throughout the rpm range, but power is down just slightly. All this at the cost of EGTs. They are much higher than desired at around 750* cruising at 60 mph. They rise quickly on any hill too.
Round 3:
It looks like we have a winner here.
I bumped the mark forward to 2* BTDC @ 1300 rpm. There's hardly any smoke, power is good, and turbo lag is almost non-exsistent. I think this is a good setup for an engine like mine - a conservative fuel rate and low pressure injectors like the 6.2 long style.
One thing that was of note:
I tested three different positions one day to find the right one, and though I moved the pump each time, the marks settled to the same place. There is no strong correlation between the position of the timing marks and the timing figure. Depending on how I jiggled the pump, I could get two timing results that had as much as a 5* difference, but at the same physical location according to the timing marks. This just confirms that the factory-provided timing marks are a great ballpark figure for when one replaces their IP, but adjusting based on the "dime method" is hit and miss for tuning.
I'm going to get some highway miles on it, and see if the economy was affected at all.
Next up is getting some new 6.5TD injectors. I figure that the better atomization of fuel will really help out.
I have a running record of my timing adjustments:
http://www.oliverdiesel.com/images/mt480/6.2_Engine_Timing_Figures.xls
