What to do before new IP?

Thewespaul said:

The fuel screw also changes the fuel curve that Mel takes a lot of time to develop, I've spoken with him extensively about this, and it is not recommended to adjust his pumps past what they are set at since it will really change how they perform. The only thing that changes the max fuel output is your right foot, if it's too smokey or too hot, don't put your foot down that much

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He told me this as well. That's why I'm apprehensive about messing the the fuel setting. He said it was a dynamic setting that affected all the other calibrations as well. I'll try to take a video of the smoking at some point and see if it's out of hand in your all's opinion. How come I see trucks running around town all the time pouring clouds of smoke out when they get on it? Seems to be par for the course around my area

Well ok but you've got to ask yourself; What's more important,the IP set to as close to perfect calibration as possible and an engine with melted pistons or a slight offset which no doubt you won't even feel behind the wheel with a engine that lasts for hundred of thousands of miles? Your playing with fire if you want to play with your EGT's with your foot.No way I'd set my trucks up like that.They get tuned for WOT,towing max gross.If they can't handle the heat,they get dialed back a bit until they can.I don't think I'd care if that cost me 50hp either. (which of course it doesn't lol.)

I will say however,yesterday I had chip maxed out and......no doubt beyond.
I had her bed and dump trailer both full of green,red oak.(two loads,over an hour away) I dropped her down manually into 2nd and let her talk a bit with the intercooler & bull moose on a couple of the steeper hills to keep EGT's near 1k.I don't mind letting her rev and keep cool.
I'm some happy for her large aux oil cooler though.

I gotta get the fresh trans in log truck.With her 5.13's,she would of made light work of that for me.

Im simply repeating what the pump rebuilder told me. He seems to widely respected so I felt I should do the same as far as IDI knowledge. I agree with you that the smoke is not how the truck came from the factory and probably isn't ideal. I'll call Mel on Monday and see what his opinion is. From the way the engine sounds I don't think the timing is way advanced but like I said before I still need to get it timed. I've heard this engine rattle before and it's far from that now. Also I've noticed with driving it, when I punch it in high gear/low rpms is when I get the smoke. After the RPMs get up to 2200 or so the smoke subsides.

2 suggestions.
1.Install an EGT gauge.
2.Don't let anyone borrow your truck.Not even for emergencies unless it's life or death of course lol.

Good luck.

Thewespaul said:

The fuel screw also changes the fuel curve that Mel takes a lot of time to develop

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Uh... have you ever taken one of these pumps apart?
The 'fuel screw' (accessable through the side-plate on the pump)
adjusts how far the plungers can open. Under normal fueling conditions, the amount of fuel available through the metering valve controls this(fuel pushes the plungers apart based no how much is available during the time period that the fill ports are aligned).

Adjusting that screw can only affect maximum fueling, because under light-load/normal-curve conditions, the plungers never open far enough to affect it!

Here's a video showing exactly how it works:

See 6:18-7:55 for the pumping element and how it works, but I really recommend watching the entire video.

adamsanders said:

Also I've noticed with driving it, when I punch it in high gear/low rpms is when I get the smoke. After the RPMs get up to 2200 or so the smoke subsides.

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You really need to watch the video here, because it explains so much.
At part throttle, the metering valve is limiting the fuel. If you floor it, the metering valve is fully open, meaning that there's less to no restriction going into the plungers, so they fill up further until they hit the spring-clip which is adjusted with the "fuel screw".

Also, the only way to really tell if you are smoking or not is to floor it(try 2500 RPM if you wish) under full load(so going up a big hill, hauling a trailer etc) - otherwise, the RPMs will rise quickly enough that you won't really see anything. The governor will then close off the metering valve some to maintain that RPM, and you are back to limited-fuel delivery to the plungers.

Macrobb said:

Uh... have you ever taken one of these pumps apart?

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Yes. And I have watched that video, however I not a pump builder and neither are you. I am simply repeating what Mel said about his pump and his settings. He is much more knowledgeable about these pumps than you or I.

Thewespaul said:

Yes. And I have watched that video, however I not a pump builder and neither are you. I am simply repeating what Mel said about his pump and his settings. He is much more knowledgeable about these pumps than you or I.

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At this point, I've messed with many pumps to get the most out of them, worn or not.
I've disassembled and rebuilt a couple as well, and they are still running just fine.

I'm confident that the recommendations I'm giving(adjust the fuel screw down until you only get a light haze at WOT under full load) will produce good results, whether or not you or Mel believes it. A DB2 pump is a DB2.

Adamsanders, let us know what Mel says Monday, ask if adjusting the fuel screw will void warranty since that may be an issue as well. it sounds like your timing is pretty close but But getting a timing light ok the pump may help the smoke, out of curiousity did you replace the injectors?

Ok I will report back. Also, no I did not replace injectors. Maybe this has something to do with it? The old injectors I'm sure don't emit as fine of a spray as they should and maybe all the fuel doesn't get burned as a result.

Quite possible. It's really recommended to replace injectors and ip at the same time, fresh injectors make a big difference

Here's a few videos to explain the smoke and the start, both on a fully warmed engine.

Here's a few revs.



Here's a hot start. Completely different sound than my heat soaked IP. This sounds like it's hitting but sometimes just won't and there's smoke at the tail pipe always. Before there was no smoke until it hit.

adamsanders said:

Ok I will report back. Also, no I did not replace injectors. Maybe this has something to do with it? The old injectors I'm sure don't emit as fine of a spray as they should and maybe all the fuel doesn't get burned as a result.

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It has less to do with the spray pattern and more the pop pressure and popping consistantly.
Unlike a DI motor, the IDI has the fuel spraying against the pre-cup, which should vaporize it pretty well(at least with the engine warmed up).
This is why you can get good power and efficiency out of R&D's Stage 1 injectors which basically just have the nozzle reamed out(which hurts the spray pattern, but helps overall flow).
In a DI motor, doing that would melt the pistons due to hot spots.

Pop pressure, though... even slight differences will change cylinder-to-cylinder timing. It's entirely possible to have an engine where 7 cylinders are "correctly timed" and 1 is "retarded" and causing all of the smoke, with a worn set of injectors.

Also, if you *do* replace the injectors, make sure to get them from a reputable source. Mel would probably be your best bet as you have his IP, though Russ(Typ4) and R&D are also reliable.

Part of the key to good injectors is new nozzles - just re-calibrating(shimming) a worn injector won't really fix the problem for long.

Thewespaul said:

Quite possible. It's really recommended to replace injectors and ip at the same time, fresh injectors make a big difference

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^^ Very much so.

adamsanders said:

Here's a hot start. Completely different sound than my heat soaked IP. This sounds like it's hitting but sometimes just won't and there's smoke at the tail pipe always. Before there was no smoke until it hit.

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Timing sounds a bit advanced. I'm hearing "knocking" when it's trying to start, sounds very much to me like when you try to start an engine with ether(because it's detonating early).

If the engine was cold, how it sounds with it /running/ would be normal to me, but hot? It should quiet down a little.

Retard the timing a little and see how she does.

edit again:
Also, your smoke with the revs? Too much fuel. You are overfueling it because the screw is turned up too high. You go up a steep grade like this and you'll be spewing a cloud of black smoke behind you, unless you are /very/ light on the throttle.

Macrobb said:

Timing sounds a bit advanced. I'm hearing "knocking" when it's trying to start, sounds very much to me like when you try to start an engine with ether(because it's detonating early).

If the engine was cold, how it sounds with it /running/ would be normal to me, but hot? It should quiet down a little.

Retard the timing a little and see how she does.

edit again:
Also, your smoke with the revs? Too much fuel. You are overfueling it because the screw is turned up too high. You go up a steep grade like this and you'll be spewing a cloud of black smoke behind you, unless you are /very/ light on the throttle.

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So are you saying I am too advanced AND overfueled? I can retard it a little more but I am already a dimes width to the drivers side of the static timing mark on the gear housing. And I do believe my gear timing is correct as you have helped me in other threads establish it.

adamsanders said:

So are you saying I am too advanced AND overfueled? I can retard it a little more but I am already a dimes width to the drivers side of the static timing mark on the gear housing. And I do believe my gear timing is correct as you have helped me in other threads establish it.

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I would try it and see what happens. There's no risk to doing so. If it works better, why not?
A new pump with worn injectors *should* be (comparatively) advanced, which would explain why you have to adjust it so far.
If you replace the injectors, chances are you'll have to advance it /from where it works best with the old injectors/ for the new optimal point.

Heck, same with the fuel screw - write down how far you adjust it(in # of flats of the 5/32 allen) and you can always adjust it back.

Dang, Macrobb! You've rebuilt your own pumps? You're WAY more adventurous than I am. I've had the top off and I've adjusted the fuel screw on the side and that's good enough for me!