well today i turned the pump up 1flat. after i turned it up i started it (first startup of the day) and the advance was on and you could tell a great deal of difference in the throtle responce and it stayed like this until the advance kicked off. once the adv quit it didnt have as much responce as before but you could still tell it was more than before i turned it up. so does this mean that i should advance the pump a little. i just set the timing a day ago to 0.5*atdc at 1400rpm's and from turning the pump up can it effect the timing that i already set?
turned pump up
- Thread starter jtate
- Start date
dyoung14
Is getting worn out
my truck seems to run better when the advance is on, i have thought about advancing it a bit or just wiring the advance on lol
Dirtleg
Full Access Member
I am no Guru but if it isn't rattling too much with the advance on then I would go ahead and advance it some. Don't let it rattle too loud with the advance off however. That can be very bad.
Diesel JD
Full Access Member
That's probably about as advanced as you want it, you could probably go all the way to 0*ATDC and still not damage anything too bad. When I get my MT1480 I'm going to put it b/t 0 and 0.5, shooting for 0.3 at 1400. Should pickup a good bit of power and fuel mileage from 2*BTDC, that's quite a bit of advance.
diesel jd i have a snap-on mt1480 thats digital and i use a lumi probe to set timing. since ive owned this machine im still not quite sure how to use it properly. i can set the pump to make the meter read either -0.5* or +0.5* at 1400rpm's but just not quite sure which one is atdc -/+
. to have that 2*btdc for power and fuel mileage that your talking about, which way do i have to rotate the pump to be btdc or did you mean atdc and if so which way do i have to rotate the pump? im just very confused about the atdc and btdc. most people say that with timing using a lumi probe it should be atdc and with using pulse timing it should be btdc or am i backwards on my assumption. sorry for all the questions just trying to better understand things. i just know that as of right now at 1400rpm's the meter reads +0.5*, if i go up anything above 1400rpm's the meter starts reading in the negatives and if i come back to a idle it will read about +8.0*. does this sound right? lolDiesel JD
Full Access Member
I have a lot to learn about the MT 1480 obviously but I will be using the exact same setup. Right now, there is an MT480 on ebay, the older analog version of your meter and it shows ATDC numbers as negatives and BTDC #s as positive. That was my thinking but...the timing should begin to retard as you advance the throttle, I was thinking as it retarded you'd be getting BTDC + numbers, based on the way the old meters were set up..... Now I'm assuming you're typing in a -20 offset to begin with...
I keep asking this question , because i haven't had anyone really explain the answer for me to understand . i purchased my meter so that i could learn how to set my own. it is better to learn how to do all my own work , then to pay someone else to do it for me .
If your using your MT-1480 as a lumy timer, then the proceedure is going to be very similar to using a Rotunda meter. The manual for which is posted in my Moose Truck album tech section. See link in sig. I don't charge people when I time there trucks, so I can't answer your question. 
Diesel JD
Full Access Member
Yeah I read the article in your webshots...still really doesn't answer jtate's question. It seems a simple one but no one seems to have a good answer. I will attempt to rephrase it, with the older MT 480 the meter shows ATDC and BTDC readings, the ATDC numbers are negative, but the BTDC numbers are positive. Since the 1480 is digital it doesn't give a BTDC or ATDC number, instead it gives for example +2* or -2*. It stands to reason that a) Any positive #s would be BTDC spec, whereas any ATDC numbers would be negative and further that larger negative numbers would be more retarded and smaller negative numbers more advanced, the reasoning for values closer to TDC being specified for higher cetane, lower BTU fuel like B100 or ULSD than the "dirty diesel" these things were designed for. Pulse timing an BTDC seems to work the opposite way for instance any positive #s are BTDC and bigger positive numbers are more advanced. For example 9.7*ATDC is more advanced than 8.5* which we used to quote as the standard. Also if the pump has a stock timing curve it will be much more advanced at idle than at 1400 or 2000 RPM, the more you advance the throttle the more retarded your timing becomes to keep from breaking things.... If I am wrong in any of this please correct me.
Mat J
Way down south
I dont know about diesel timing in this case but when a gasser goes up in rpm ignition advances. If you retard it you would loose a lot of power.
A simple test to anser JTATE, set your pump so you know you are pretty retarded to the drivers side, see what the meter reads. If it says - then you know that - is ATDC if it says + then you know + is ATDC.
Then you can go about and set to .5-/3 ATDC at 1400 and you will be good to go.
A simple test to anser JTATE, set your pump so you know you are pretty retarded to the drivers side, see what the meter reads. If it says - then you know that - is ATDC if it says + then you know + is ATDC.
Then you can go about and set to .5-/3 ATDC at 1400 and you will be good to go.
thanks diesel jd for the responce, you hit the nail on the head as for as understanding my questions. from what im seeing on my meter at idle it reads +8* btdc, now as you raise the rpm's the timing starts to retard heading toward tdc where it will settle at +0.5* btdc at 1400 rpm's. anything under 1400rpm's reads + which im guessing is btdc. now as you overcome 1400rpm the meter will eventualy start reading in the - range which must be atdc(retarded). now if the timing retards the more throtle you give then wouldnt you want to hit your goal of +0.5* around the 2000rpm mark to be in the power range at higher rpm's? does that make sence?
thanks mat for the answer. ive alredy tried that and have pretty much come to the conclusion that + is btdc(advanced) and - is atdc(retarded). now if i set the timing to atdc (neg) like everybody says the timing should be set at the truck can barely get out of its own way. however if i set it to btdc(pos) then it has more power. now with the timing set at +0.5 the power is good but it gets better at +2.0* and up.
Diesel JD
Full Access Member
That just doesn't seem right for it to be a dog at -0.5ATDC @1400 rpm, I feel either I misunderstand the way this meter works or your pump may be shot. That should be about the same as 9.5 BTDC with the pulse method at 2000 rpm. I recall some people have checked with lumy and pulse and found that the specs are identical essentially just that the luminosity method uses these fragile, difficult to replace luminosity probes that makes them fall out of favor.
