timing the 7.3l with mt480 lumy method

[FORDF250HDXLT]

im lost on the numbers guys.nothing seems to add up for me at all. using the lumy method for the 7.3l is supposed to be possible.i wounder how many actually have,and what they set the meter too?
my pump is now set to -7 ADTC @ 1400rpm.and this is advancing the pump (turning my mark from lined up,and matching closely to the pic of which Mel refers to above.)
my cetain value i know is approx 40-42.
my engine has more rattle than when i started with matching marks and about -8.5 ATDC.
the more advanced i go (more rattle,and making the line on the ip go toward the pass side) the meter reads closer to BTDC.
if i where to try 1-2 degree's like iv read,the line would be WAY over to the pass side,and it would likely do whos what.i don't dare to advance it that much.know way the mark want to be way over so far,nor sound so god awful.i took it to -3ATDC and went for a ride-sounded REALLY bad.
what is -6ATDC in relation to pulse timing?
i have the meter set to 20 degree offset.the lower 300? or what - 1400rpm setting.
i have read where some claimed they needed to try setting 1400-6000 rpm,and use 2000rpm,yes even with lumy method,but my meter(s) just peg when i do that.
i have 3 lumy probes and two meters.tried 'em all.
using the first cylinder on on the pass side of the engine,and have tried using #4 as well,with same readings.
perhaps i just don't understand what - values mean on the meter,and what 2 ATDC equates too?
can't be using the BTDC side of the meter,cus my mark would be on the other side of the ip,rather than advanced,and i be retarded from lined up and with less rattle.so i didn't even bother trying that of course.
im lost.
for the pic i mention,see here;
http://www.oilburners.net/forums/showthread.php?p=485454#post485454

 

[FORDF250HDXLT]

all's good guys! 6-7 degree's is correct for my cetain and elevation.
i found a chart i had forgot about reading before.
i knew i just had to be close.

 

[johneich]

Just something Mel had written, I thought you might want to read.

"The problem with the lumy method is it relies to heavily on the injector, and the readings can be erratic. In theory the method is sound, but in application it falls short. Just ask anybody who has every done both, and your going to hear pulse is the way to go every time. Todd was over my place last night, and I timed his truck to 8.5 PBTDC on the nose. He was 3 degrees retarded. Man that thing will scoot now!"
-Mel

Todds reply:
"Thanks again Mel!
I'll post next week after I run a tank or two through to see how my mileage is. My truck definitely likes 8.5 deg timing!
5.5 degrees was with the marks lined up on the pump, for what it's worth. It seems like 3 degrees has made a big difference.

 

[FORDF250HDXLT]

yeah.that's pretty much what mine was as well.3 degree's + retarded.
now to tweak just a bit more and go for a test run tomorrow.

in case other old school lumy timing guys need it:

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hmmm.bummer.

 

[Diesel JD]

You set it at -6 ATDC? I didn't know elevation had any effect on what the timing should be. I know cetane does. I have the MT1480 and always set trucks between 0*ATDC and -3 at 1400. I assume higher cetane values, I do not have the hydrometer to check. I assumed that pump fuel would be much higher than 40-42 since going to the ULSD fuel. I know my biodiesel is going to be closer to 47 and up. I run my truck at around -1.5- -2.5, I will probably set it closer to 0 when I retime it and check my injectors. I wouldn't worry about where the timing marks are, only what the meter says unless I had a reason to suspect the meter was giving me BS readings. Yes you want a 20* offset if you are using the #1 cylinder and the correct hole for taking the rpm readings.

 

[FORDF250HDXLT]

nope.fuel sucks here.pretty poor.40-41,if your lucky 42 lol.
0-3k altitude on 38-42 = 6 ATDC according to that chart and this has more rattle than im used to,and i did try going as far as -3 and it sounded really,really bad going down the road.i knew something wasn't right with the line way so far over towered the pass side,and the over rattling of the engine.sounded like a lot of rubbing metal,and not a normal diesel engine sound at all.real bad.so i didn't even bother trying for 2-1 ATDC like iv read to try,i knew that was far too advanced as is.i think im around 7 right now,im still playing around a bit,and that's got the mark over pretty good from lined up as is,but i'll go another degree to 6 and go for a ride tomorrow.
the 7.3l was never supposed to be timed via lumy method is what im finding,so it may vary greatly as to what a 6.9l reads.im really not sure.not a lot of people time via lumy method anymore,and half of those rare few who do,all seem to have 6.9's lol.


this goes good with the above chart (if someone can fix that?)
for those who need to find the cetane value.can't really do much without it with the lumy meter imho;

1. Obtain a fuel sample and check the cetane value using Ford Rotunda Tool no. 078-00121 supplied
with Ford Rotunda Tool no. 078-00200 or equivalent (6.9l_ engines only). Cetane value is determined
by measuring the specific gravity {density) of the fuel with the fuel temperature between 75 and
95-degrees F. Poor quality fuel can affect diesel engine performance. Check the cetane value as
follows:
a) Fill the hydrometer Container with fuel until the hydrometer floats.
b) Gently spin the unit to break surface tension. Read the number at the lowest point of the
fuel level in the hydrometer. Record the number and refer to the cetane value conversion chart.

Fuel hydrometer reading-to-cetane value conversion chart

Hydrometer Reading Cetane Value
.837 50
.846 47
.849 46
.858 43
.862 42
.876 38

 

[Diesel JD]

I don't think there's any difference in the timing between a 6.9 and a 7.3, I honestly don't know about the altitude thing, you could be right. I can't imagine any IDI would be anywhere close to right at 6 or 7 ATDC. Where did this chart come from? Those values sound very conservative. What does it say for sea level? Timing spot on does have a lot more clatter than a lot of people are used to, if you're very experienced with IDIs then you probably know what too far advanced sounds like, if this is the only one you've worked on, maybe it's supposed to sound a little more clattery than you're used to? Maybe I'm way off base here, but I think it can't possibly be right at 6 ATDC.

 

[FORDF250HDXLT]

sea level to 3000 feet on 38-42 cetane diesel = 6 ATDC.
3000' and above 38-42 cetane diesel = 7 ATDC
then you drop a degree etc.etc.damn that chart lol i wished it worked.i don't know where it came from.it matches what i feel is correct,and was posted by someone on FTE.
there's no cetane/altitude chart here at all that iv found? how have you guys been timing via lumy?

i dunno,but that's got some pretty good rattle to her.
with my mark straight up,i was reading over closer to 9 ATDC and though retarded a few degree's it has been running pretty good there.
-3 puts my timing mark way over to the pass side,i know you can't go by this much,however it was lined up and running just fine.good power and all.but 3 looked and sounded downright miserable.i couldn't image anyone running it like that.very,very loud going down the road,and not healthy at all.even though im a complete novice,i know that sound was not a good sound at all.

 

[OLDBULL8]

Here is an excerpt from supposedly an expert on fuels.

Diesel at the pump can be found in two CN ranges: 40-46 for regular diesel, and 45-50 for premium. The minimum CN at the pump is supposed to be 45. The legal minimum cetane rating for #1 and #2 diesel is 40. Most diesel fuel leaves the refinery with a CN of around 42. The CN rating depends on the crude oil the fuel was refined from. It varies so much from tanker to tanker that a consistent CN rating is almost impossible. Distilling diesel is a crude process compared with making gasoline. Gasoline is more of a manufactured product with tighter standards so the octane rating is very consistent. But, the CN rating at the diesel pump can be anywhere from 42-46. That’s why there is almost never a sticker on a diesel fuel pump for CN.

Premium diesel has additives to improve CN and lubricity, detergents to clean the fuel injectors and minimize carbon deposits, water dispersant, and other additives depending on geographical and seasonal needs. More biocides added in the south in summer, more ant-gel added in the north in winter. Most retailers who sell premium diesel will have little brochures called POPs (Point of Purchase) at the counter explaining what’s in their fuel. Please don’t ask the poor clerk behind the counter any technical questions after reading this discussion. All they need to know how to do is sell you beer, milk, cigarettes, lottery tickets, and take your money.

 

[Diesel JD]

It just sounds odd to me. I've never heard of anyone here adjusting timing for altitude. If anything it seems like retarding the timing at altitude would be damaging, since more timing leads to lower EGTs to a point. I'd be suspicious that your timing gear was off a tooth and maybe suspicious of your timing meter too. Maybe your truck is timed pretty close and that meter is giving you nonsense for some reason. Sounds like you are doing it right though. You are using the timing port further to the left that fits the magnetic probe real snug correct? That is the one for which the 20* ATDC reading is correct. Personally I'd also check another cylinder if I got readings like that. I don't know how much offset the 480 allows you to key in, but the 1480 allows you to use whichever cylinder you want. Those who don't like luminosity timing point this out as a potential flaw in lumy timing: an injector or cylinder that is stronger or weaker than the others can throw your timing off. I think #4 has all the same offsets as #1 does. I have those other numbers around here somewhere if you're interested. I had always heard 1.5 ATDC on cetane 47 and up and on bad fuel closer to 3.5-5* ATDC. Bad fuel meaning higher BTU/unit and lower cetane. I'd love to hear a sound clip of it. Here's how my truck sounds with around -1.5 to -2 ATDC timing probably a little more than that since it was cold and the cold timing advance was on. http://www.youtube.com/watch?v=k-B9SAY9W54

 

[FORDF250HDXLT]

it was retarded at -8.5 ATDC when i started.which had the timing marks on the ip pretty much set dead on.
i advanced it to -6 ATDC and finalized this setting by locking all bolts down today.this puts my ip's timing mark very very close to the reference point as noted in this thread;
http://www.oilburners.net/forums/showpost.php?p=485434&postcount=1

with sea level - 3000' altitude and 41(ish) cetane value. i feel im right on the $ after a test drive.
before the chart,and just "attempting" to go by the lower -ATDC settings referenced by others it sounded god awful loud and my mark was clearly no longer in the "zone" (clearly too far too the pass side) either,and that was just advancing to -3ATDC.
i sound pretty much the same as your engine.not as much rattle of course as that with a warm engine.like i say,to the ear it sounded pretty good with lack of the advance before started and went pretty good.i was always happy with the power and everything.now advanced 2.5 degrees or so,the engine is clearly more loud.makes me want to soundproof the firewall out on the engine sooner now lol.
i can feel the increase in performance.mainly what i feel is more take off nuts and it feels more "free rolling" down the road so to speak.
yes.i used the skinnier holder/20 degree offset/engine fully warm with cold advance off/no accessory load/up to the 1400 rpm switch/set the engine to rev @ 1400rpm/tested all of 3 of my lumy probes two meters and both #1 and #4 cylinders and read the same values for all.#4 did read slightly more retarded than #1.but not enough to amount to much.
she's going great.besides a little more engine noise,im liking it.
anxious to test fuel economy now.

edit,
additionally,this site also states:
"GM spec calls out TDC @ 1400 RPM, and Ford's NA specs vary depending on the elevation and your fuel cetane rating. Figures range from 4° to 7° ATDC @ 1400 RPM."
which agrees with my settings/elevation and fuel, as well.
http://www.oliverdiesel.com/tech/timing.htm
id sure like to read where he read it first though.

are you zeroing out your meter before you start? read on the meter it says to zero out to the "extreme" left.maybe those who get away with such advanced -ATDC (lower numbers/closer to O/BTDC) are running like 55+ cetane fuel and have your meters zeroed out to -20 mark rather than the "extreme" left? hmmm.

 

[Diesel JD]

Sounds like you did everything right. I may just be wrong in my approach, but the timing figures work well with my truck. If it was starting to sound really violent you probably made the right call not to run it that way. I have no idea what the cetane content of my biodiesel is but I'm sure it's a lot higher than 41. Most all the diesel I see for sale at the pump is also "Premium Diesel" whether it actually meet those specs that were posted on your thread I do not know. I know RLDSL is an advocate of advancing the timing a bit, but his experience was that this could not be done safely before the switch to ULSD was made and the cetane ratings went up and the BTU content plummeted. I hope you didn't feel like I've been too critical of you, I have just had a different experience with my truck and other IDIs. So, I don't know what's up with you and your truck but if you've found a spot where the fuel economy is to your liking and the noise and emissions aren't bad you should definitely run it there. It certainly won't hurt anything.

 

[FORDF250HDXLT]

no,no.didn't cross my mind at all that you where being critical of me.in fact being my first attempt at this,that's exactly what i was looking for anyway.
iv searched and read i think every comment here you have made about timing lol.
i find this very interesting and fun.well,ok besides getting at them dang ip bolts!
indeed bio would be a much different setting.i sure wish they had that around here to try.
yeah just taking her to 3 ATDC really scared me.it was not a healthy engine sound at all.im probably lucky i didn't melt the gp's with just the short test run,that's how bad it sounded.actually gained performance by bringing it back to 6 as well.so she's really,really close if not exact i feel.
3 made it sound like it lost all oil pressure under load.that's how extreme it was.so i just knew,right off it wasn't right.turned right around and hit the net again.

 

[Diesel JD]

The bio is great stuff to work with except for if you make a mistake in the processing, then you'll be changing filters more frequently until the bad stuff is completely out of the system. Up there in Maine you might have a hard time keeping anything over B5 or B10 liquid in the winter. As you can see we think 27 is a really cold morning down here. I run the B100 or a high blend all year long.