cranking advance for 2.6

[PowerRam348]

does anyone know what the cranking advance is for the 2.6?? i either am looking in the wrong places or am just not finding it for whatever reason.

[pennyman1]

stock timing is 7 degrees btdc; not sure what you mean by cranking advance. As far as I know, it doesn't advance for cranking.

[PowerRam348]

on the megajolt unit i have to set a cranking advance. it has a default cranking advance of 12 degrees. trying to build an ignition map is one of the harder things i've done.

[PowerRam348]

i guess a better question would be: does anyone know what the peak vacuum advance is at WOT.

[camoit]

Just set the cranking at 2 deg btdc. Then the total advance to 7 deg.

[PowerRam348]

thanks a lot for the timing numbers camoit. got the truck running today. now it just needs fine tuning. thanks to everyone who gave their input on my motor build.

[camoit]

What you need to do is look in the manual section to find out what the total advance is. From there you can work back wards from 7btdc. @ 800 RPM. I never looked to see what it might be. I just figured that 2 and 7 is a good starting point and would get it running. You need to find the timing curve. If you take the distributer to a shop that has a distributer machine you can map the advance curve. The problem is finding one of the machines. I think it should have some where around 22 Deg of total advance @ 3200 RPM But this may be wrong. Here is a video to check out. I could probably find a machine local here but I need to come up with a distributer. Mopar_Ja has all of my old parts.

I put in a PM to LSR Mike. He is the only guy that might have needed to map the curve for the performance he is running. Sun had books on what the curve should be. Try to find them. There around, some where.

[camoit]

From LSREMike.

Re: Timing curve

It's actually controlled by the ECU, the distributor is only there to distribute the spark from a single coil to the 4 cylinders. the base of the Distributor has the CAS, or Crank Angle Sensor, built into it. it gives the position of the motor to the ECU which controls the timing. that's why you have to ground the plug when setting the base timing on FI Truck, it puts the ECU in calibration mode.

I'll post up the excel file with the stock timing curve extracted from the ECU.

[PowerRam348]

thanks for the timing info. i have no idea how long it will take me to get the map done but when i get my timing mapped i will post it for everyone. thanks again to everyone for all the input.

[camoit]

Here is what LSRMike sent me. It was in Excel. We can't put up Excel things on the board for some reason.
I hope he chimes in and explains just what you are looking at.

Air Fuel Ratio Fig. #1
AF-Ratio.jpg


Air Fuel Ratio Fig. #2
AF-Ratio1.jpg



Ignition Advance Fig. #3
Ign-Advance.jpg

[LSR Mike]

The first 2 graphs are the Air/Fuel Ratio (AFR) targeted by the ECU in different formats.
The 3 components are RPM, Load (Vacuum), and the AFR the ECU wants to see at those points. it looks at the o2 sensor for the AFR reading and adjust the fuel injector pulse width to get the proper amount of fuel.

The last graph is the Timing Map basically showing you the timing advance for the RPM and Load.
here are the actual Numbers.

RPM across the top
The ignition advance number below
the 9 rows of numbers are the S1 to S10 load lines shown in the graph.
The Bottom line being low Vacuum and the top line being High Vacuum.

0 750 1000 1250 1500 1750 2000 2250 2500 3000 3500 4000 4500 5000 5500 6000
8 8 13 19 29 32 40 40 40 40 40 40 40 40 40 40
8 8 13 19 29 32 40 40 40 40 40 40 40 40 40 40
8 8 18 24 30 35 40 40 40 40 40 40 40 40 40 40
8 8 18 24 30 35 38 38 38 36 35 35 37 37 37 37
8 8 16 19 21 27 30 30 31 28 28 28 30 30 32 33
8 8 9 13 13 18 18 20 21 21 20 20 25 28 28 30
5 5 8 9 10 11 12 15 16 16 17 16 20 22 24 26
3 3 7 8 9 11 11 14 15 16 16 15 17 21 23 25
2 2 6 7 8 10 10 14 15 16 16 14 16 20 22 24
0 0 4 5 6 8 8 11 12 13 13 12 15 19 21 23

[PowerRam348]

thanks for the timing info. it gives me a good idea of where to start. i still have a lot more research to do and driving the truck to get the timing figured out. i need to build a knock detector (basically a stethiscope) to listen for knock. once i get the hand of reading the recorded run-time data i will be able to better tune the ignition. how do i upload videos?

[LSR Mike]

you going Turbo? what's the Knock detector for?

[PowerRam348]

i'm setup to run turbo if i want to but i'm not gonna right now. the knock detector is just to help me tune the motor and listen for things that can't be heard by the naked ear.

[Acuta73]

Keep watching this thread and not understanding it..anyone care to elaborate as to WTH you mean by mapping the timing curve?

I like 3D charts, if I had SOME idea of what I'm looking at...

[camoit]

The map that he is trying to build is for the ignition timing over the RPM band he is running. (XXX= unknown variable) When the engine is not running it should have about 0-2 deg of advance. Once it starts the fly weights in the distributer give it some advance. This is 7 deg at 650 RPM. Now as the engine RPM increase it needs more advance. The fly weights will give it a steady increase in advance until XXX RPM is reached. This can be controled by changing springs and fly weights. This will change the curve. The vacuum advance will add XX deg of total advance when the vacuum port is exposed to manifold vacuum as the butterfly open. If you loose too much manifold vacuum then the distributer will retard the timing. This might, or might not be advantageous depending on the application you are working on. If it's a stock engine then it will help keep you from dropping pistons through the oil pan. As the RPM reaches the top of the cams degree limit the power falls off. Also the valve springs come into play at high RPM. Just ask LSRmike. He it the high RPM master. He needs to keep things opening and closing within .00253 seconds of the power stroke. If things go wrong on his truck,, well lets just say it's a bad day at the speeds he drives. The idea is to have the fire in the cylinder starting to burn just before the intake valve is seated, and the compression stroke is at the correct place. To soon and it backfires through the intake or pings. To late and the engine looses out on the exploding fuel vapor in the cylinder. Then it's a loss of power. Hope this helps.

When he gets it figured out it will look something like this.

Timing ------------------------- RPM
-2------------------------------ 0
---7---------------------------- 650
------10------------------------ 975
--------15---------------------- 1800
--------------17---------------- 2100
----------------19-------------- 2400
----------------------22-------- 3000
----------------------------32-- 3500
------------------------------38 4500

[PowerRam348]

everything helps. i have been doing research on timing advance for the last two weeks and am still learning. i didn't realize that the shape of the combustion chamber (ie. hemispherical, pent-roof 4 valve) has a lot to do with how much timing advance the motor can handle because of the burn time. my motor is stock for the most part... other than bored 20 over and balanced, but so far i have found that if i bring the motor to full advance at about 3500 rpm i get better power thru the rpm range. i am actually thinking of going to full advance sooner than that even. currently i am running my full advance at 32 degrees. as i understand it, a hemispherical combustion chamber can handle up to about 40 degrees of advance.

[TintedRam50]

Ive had the edis for sometime now, I will send my map soon. Main thing is you gotta find what your motor needs, run down the road with the lap top and find the max advance for each load and rpm. Most power is a couple degrees below spark knock. Every engine will have different timing for power.

[TintedRam50]

http://www.mightyram50.net/phpbb3/vi...6fc9b459c12740