More timing=more boost?
11-15-2005, 09:00 AM
#31
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G1625S.. I read your post on another thrad.., so now I know.. sort of.. what the AFC is??
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Sounds to me like your truck is tuned really well. No matter what the orientation of the pin, it's still just going to sit there untill boost overcomes your AFC spring/starwheel setting. Once there's enough boost to push the pin down, there's ''usually'' enough air to burn the additional fuel provided by the cone. To maximize the effect, run your starwheel down a half turn at a time, going for a test drive each time. Each half turn will allow the pin fueling to come ''into play'' at a lower boost level. Eventually, it'll come in too quickly and you will smoke. Back the starwheel to the previous setting and your AFC is now adjusted for max clean power (at your current full-fuel setting). FWIW, the full fuel screw has everything to do with smoke. When I put my new/reman pump on, lock collar and all, I could dump the clutch in 3rd and nary a puff---nuttin! I rotated the pin, ran the starwheel down, maximized the throttle travel---everything! Still, no puff. Then I gave the full fuel screw some twisting---sooot city! A little AFC tweekage later and most of the black stuff was gone. What I'm trying to say is the AFC settings are there to help tune for the fueling level you're at, but rolling the black stuff really begins and ends with the full fuel screw (and injectors).
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Is thhis what your'e talking about for tuning the AFC?
Thanks
================================================== =====
Sounds to me like your truck is tuned really well. No matter what the orientation of the pin, it's still just going to sit there untill boost overcomes your AFC spring/starwheel setting. Once there's enough boost to push the pin down, there's ''usually'' enough air to burn the additional fuel provided by the cone. To maximize the effect, run your starwheel down a half turn at a time, going for a test drive each time. Each half turn will allow the pin fueling to come ''into play'' at a lower boost level. Eventually, it'll come in too quickly and you will smoke. Back the starwheel to the previous setting and your AFC is now adjusted for max clean power (at your current full-fuel setting). FWIW, the full fuel screw has everything to do with smoke. When I put my new/reman pump on, lock collar and all, I could dump the clutch in 3rd and nary a puff---nuttin! I rotated the pin, ran the starwheel down, maximized the throttle travel---everything! Still, no puff. Then I gave the full fuel screw some twisting---sooot city! A little AFC tweekage later and most of the black stuff was gone. What I'm trying to say is the AFC settings are there to help tune for the fueling level you're at, but rolling the black stuff really begins and ends with the full fuel screw (and injectors).
================================================== =
Is thhis what your'e talking about for tuning the AFC?
Thanks
11-15-2005, 09:08 AM
#32
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Thread Starter
FR: How do your boost #'s compare to those with the old pump? If you do have the full on BANKS kit, you have the coveted 14cm exhaust housing. Double check that your wastegate actuator is not stuck and that there's indeed some sort of boost reference hose connected to it. Your high temps and boost could very well be linked to a wastegate not opening. A 14cm housing that isn't wasting is a wee bit small to be tugging 10k around.
11-15-2005, 09:12 AM
#33
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Thread Starter
Originally Posted by FerranRico
G1625S.. I read your post on another thrad.., so now I know.. sort of.. what the AFC is??
================================================== =====
Sounds to me like your truck is tuned really well. No matter what the orientation of the pin, it's still just going to sit there untill boost overcomes your AFC spring/starwheel setting. Once there's enough boost to push the pin down, there's ''usually'' enough air to burn the additional fuel provided by the cone. To maximize the effect, run your starwheel down a half turn at a time, going for a test drive each time. Each half turn will allow the pin fueling to come ''into play'' at a lower boost level. Eventually, it'll come in too quickly and you will smoke. Back the starwheel to the previous setting and your AFC is now adjusted for max clean power (at your current full-fuel setting). FWIW, the full fuel screw has everything to do with smoke. When I put my new/reman pump on, lock collar and all, I could dump the clutch in 3rd and nary a puff---nuttin! I rotated the pin, ran the starwheel down, maximized the throttle travel---everything! Still, no puff. Then I gave the full fuel screw some twisting---sooot city! A little AFC tweekage later and most of the black stuff was gone. What I'm trying to say is the AFC settings are there to help tune for the fueling level you're at, but rolling the black stuff really begins and ends with the full fuel screw (and injectors).
================================================== =
Is thhis what your'e talking about for tuning the AFC?
Thanks
================================================== =====
Sounds to me like your truck is tuned really well. No matter what the orientation of the pin, it's still just going to sit there untill boost overcomes your AFC spring/starwheel setting. Once there's enough boost to push the pin down, there's ''usually'' enough air to burn the additional fuel provided by the cone. To maximize the effect, run your starwheel down a half turn at a time, going for a test drive each time. Each half turn will allow the pin fueling to come ''into play'' at a lower boost level. Eventually, it'll come in too quickly and you will smoke. Back the starwheel to the previous setting and your AFC is now adjusted for max clean power (at your current full-fuel setting). FWIW, the full fuel screw has everything to do with smoke. When I put my new/reman pump on, lock collar and all, I could dump the clutch in 3rd and nary a puff---nuttin! I rotated the pin, ran the starwheel down, maximized the throttle travel---everything! Still, no puff. Then I gave the full fuel screw some twisting---sooot city! A little AFC tweekage later and most of the black stuff was gone. What I'm trying to say is the AFC settings are there to help tune for the fueling level you're at, but rolling the black stuff really begins and ends with the full fuel screw (and injectors).
================================================== =
Is thhis what your'e talking about for tuning the AFC?
Thanks
Yup, that's a good start. In Jim's case, he was looking for a little more fuel, whereas you're looking for perhaps a little less, to cool things down. Lemmie see if I can dig up some more info/pics.
11-15-2005, 09:53 AM
#34
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I'd still like to know if someone has pulled with their truck under 2 different timing scenarios and noticed a dramatic different in coolant temps like my truck appears to have experienced.
brad
brad
11-15-2005, 11:38 AM
#35
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Originally Posted by G1625S
This is a tough one to explain. It makes sense in my head, but I've typed this about 5 times and it still doesnt' read right, but here goes...
Boost is partly a function of how fast the turbo is spinning. Turbo speed is determined by the flow of hot exhaust over the turbine wheel. Spinning up the turbo at low RPM with hot exhaust is what gives the percieved low end 'grunt' of these engines when the timing is set per-factory. By advancing the timing, more of the hot combustion gasses that would otherwise be expelled to spin the turbo are contained in the cylinder for a better burn. The resulting exhaust coming out of the manifold is now cooler and slower moving, slowing the spool of the turbo---hence the sluggish low end. Boost will be down across the board since the timing we're messing with by moving the pump is static. The up side is a better burn and higher horsepower in the mid and upper RPM range. There are many inter-related factors that come into play other than what I've noted. Anyone who'd like to add a detail or correct me, please step in. Tuning is always going to be a series of compromises with mechanical injection, since you can't really tune on the fly.
Boost is partly a function of how fast the turbo is spinning. Turbo speed is determined by the flow of hot exhaust over the turbine wheel. Spinning up the turbo at low RPM with hot exhaust is what gives the percieved low end 'grunt' of these engines when the timing is set per-factory. By advancing the timing, more of the hot combustion gasses that would otherwise be expelled to spin the turbo are contained in the cylinder for a better burn. The resulting exhaust coming out of the manifold is now cooler and slower moving, slowing the spool of the turbo---hence the sluggish low end. Boost will be down across the board since the timing we're messing with by moving the pump is static. The up side is a better burn and higher horsepower in the mid and upper RPM range. There are many inter-related factors that come into play other than what I've noted. Anyone who'd like to add a detail or correct me, please step in. Tuning is always going to be a series of compromises with mechanical injection, since you can't really tune on the fly.
11-17-2005, 09:31 AM
#36
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I'm thrilled now.. I guess.., since I haven't tested it under a load..
I took the pump out yesterday and did a bench timing.., with the metering gauge.. it's easier than I thought.., then while at TDC rotated the coupling gear (where the pump attaches) until I eyeballed that it would line up and slipped the pump back in, after a couple of tries in order to get the proper travel up (for timing) on the housing I was able to get it.., the pumps mark now sits below the engine housing mark and I can time up to 5.10mm at full rotation.., however I left it at 3.5 mm advance (problem is I can't retard anymore below 3mm.., but with the performance injectors and the tweaked pump I need the advance capability..)
One thing that really helped, since I was working by myself, was to mark the flywheel at TDC and also at Zero point, backwards where the pump is not indexing anymore (no needle movement)... so i was able to watch them as I turned the engine over with the barring tool.. best $50 I've ever spent... it makes things sooo easy..
So I went out on the freeway and the response is incredible.., at least it had never ran this good.., I would cruise at 70 mph, punch it and get up to 90 mph in no time.., it only blew smoke upon the punch and then it'll take off with hardly noticeable smoke..
Boost was 2 lbs at idle and 29 at full throttle.., but with noticeable increased power..
The temp stayed at the 2nd mark right (4 marks on the line) of the C on the dummy gauge.., no matter how hard I throttled it...
Guess that i'll be loading the Jeep on the trailer this weekend and taking it out for a spin and see how the temperature and mpg goes.. it may be a different story..., but that's what tweaking is all about..
Thanks for all the advice.., I Hope that my problem is solved..
I took the pump out yesterday and did a bench timing.., with the metering gauge.. it's easier than I thought.., then while at TDC rotated the coupling gear (where the pump attaches) until I eyeballed that it would line up and slipped the pump back in, after a couple of tries in order to get the proper travel up (for timing) on the housing I was able to get it.., the pumps mark now sits below the engine housing mark and I can time up to 5.10mm at full rotation.., however I left it at 3.5 mm advance (problem is I can't retard anymore below 3mm.., but with the performance injectors and the tweaked pump I need the advance capability..)
One thing that really helped, since I was working by myself, was to mark the flywheel at TDC and also at Zero point, backwards where the pump is not indexing anymore (no needle movement)... so i was able to watch them as I turned the engine over with the barring tool.. best $50 I've ever spent... it makes things sooo easy..
So I went out on the freeway and the response is incredible.., at least it had never ran this good.., I would cruise at 70 mph, punch it and get up to 90 mph in no time.., it only blew smoke upon the punch and then it'll take off with hardly noticeable smoke..
Boost was 2 lbs at idle and 29 at full throttle.., but with noticeable increased power..
The temp stayed at the 2nd mark right (4 marks on the line) of the C on the dummy gauge.., no matter how hard I throttled it...
Guess that i'll be loading the Jeep on the trailer this weekend and taking it out for a spin and see how the temperature and mpg goes.. it may be a different story..., but that's what tweaking is all about..
Thanks for all the advice.., I Hope that my problem is solved..
11-17-2005, 06:29 PM
#39
Adminstrator-ess
The TDC pin could be off considerably too. His TDC reading could be off 10 degrees for all we know. The housing that the timing pin is in is adjustable, and there's a procedure for recentering it to make sure it's correct.
This is why I haven't bothered with actually timing my truck. I just have it cranked as far as it will go, and I still think it needs a little more.
This is why I haven't bothered with actually timing my truck. I just have it cranked as far as it will go, and I still think it needs a little more.
11-17-2005, 06:34 PM
#40
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I was thinking the same thing...Haven't gotten saucy with the dial indicator yet, so I really can't say what advancing the gear and pulling the pump all the way back nets. I did put a little load behind her yesterday---about 5k. Definitely less bottom end than when I brought my 5ver home, and that was 10k-ish. I didn't lug it at all, just kept her wound up and it pulled very strong with no coolant temp issues. This was all steep side hills at about 40 mph and truthfully, not much weight. I'd still back the timing gear off if I were pulling my 5er around, but for daily driving, it's been great. 28 degrees this AM and I just hit the key with no grids--not even a skip and settled right into a smooth idle. Love my old rattle trap
11-19-2005, 09:34 AM
#41
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My truck is a 93, thus the plate on the Cummins housing says to time it at 2.5mm, so I figured that with the injectors and tweaked pump I could give it 1.0mm more to 3.5mm.. just to be conservative, I'm not set on it and will test to see how it does.. and adjust accordingly, now that I know how to do it.., it's fairly simple to back off one tooth to allow me to go back to 2.5mm, it ran Great with no load, might be different with a load.., I pull around 8K lbs (2K trailer and 6K Jeep) +- ...
To set TDC I took off the plunger and with a mirror made sure that the pin hole was dead center on the housing hole, then I marked the flywheel at the sensor that's hanging there, then I backed off until the needle moved no more and marked that as my meter zero out point on the flywheel too.., now that's all I have to have and not worry about running back and forth from the barring tool and the TDC pin to set the TDC.
It got down to 35 degrees here this morning.., and when I cranked the truck on it took it a little shudder and lots of bluish smoke until it warmed up.., I guess it's because of the cold?
To set TDC I took off the plunger and with a mirror made sure that the pin hole was dead center on the housing hole, then I marked the flywheel at the sensor that's hanging there, then I backed off until the needle moved no more and marked that as my meter zero out point on the flywheel too.., now that's all I have to have and not worry about running back and forth from the barring tool and the TDC pin to set the TDC.
It got down to 35 degrees here this morning.., and when I cranked the truck on it took it a little shudder and lots of bluish smoke until it warmed up.., I guess it's because of the cold?
11-19-2005, 06:40 PM
#42
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Yeah, mine is a little harder to start since advancing the timing too (in the cold). It was 8* here one morning though, and it still starts with a couple cycles of the grids
11-20-2005, 11:46 PM
#43
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Ummmmmmm......NOT 2.5mm 
it's 1.25mm for the 93's....I think you should do some tinkering and git 'er down a tad bud....cylinder pressures and temps will take that head gasket out real quick if your not super lucky...!!!!!!!
I can't believe no one saw that...
pb...
it's 1.25mm for the 93's....I think you should do some tinkering and git 'er down a tad bud....cylinder pressures and temps will take that head gasket out real quick if your not super lucky...!!!!!!!I can't believe no one saw that...
pb...
11-21-2005, 07:39 AM
#45
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I could swear that I saw 2.5mm .., but then I ain't as good as I once was.., eyesight that is 
.., I'll recheck it with a magnifying glasses today.., if it quits raining..., ain't planning to dirve it anytime soon anyway.., thanks for the watchfulm eye.., if that's the case I'll back it out rigt away..
Why were some of ya'll posting advances on up to 7mm?.. is that for older engines?
.., but then I ain't as good as I once was.., eyesight that is .., I'll recheck it with a magnifying glasses today.., if it quits raining..., ain't planning to dirve it anytime soon anyway.., thanks for the watchfulm eye.., if that's the case I'll back it out rigt away..Why were some of ya'll posting advances on up to 7mm?.. is that for older engines?