"Turning" the Delivery valves - PeachParts Mercedes-Benz Forum

MTUpower · #1 08-18-2008, 09:56 AM

"Turning the delivery valves" has been proposed as a way to increase fuel to the engine and it goes like this-
1)Loosen injector lines at the IP. 2) Loosen the two 13 mm nuts above and below the 15mm "housing" on the IP. 3) tighten the 15mm "housing". 4) Lower idle as it will increase.
This has been done on many other Bosch IP's according to some people with great success. Several others have said this is not recommended as you may throw your engine's timing out of whack. I'd like to hear from those that have done this on a 617 and the results/problems/issues, and others who think this is a bad idea and why. You can see threads at schuman and superturbodiesel on this idea.

KarTek · #2 08-18-2008, 10:00 AM

I would think that if you did this, you'd have to put the pump on a flow machine make sure it was back to specs as far as balance between elements.

My question is: Does this adjustment effect timing or volume?

Bajaman · #3 08-18-2008, 04:41 PM

Sounds like a bad idea to me. Like FI said in the super turbo forum, this adjustment is meant for timing...

MTUpower · #4 08-18-2008, 05:43 PM

okay- it's a bad idea. Why? Why do some people do this apparently with success?

Bajaman · #5 08-19-2008, 08:38 AM

I am not familiar with the inner workings of a pump, but could it be that by turning the delivery valve out you are increasing the effective stroke? This is just a guess. Sometimes I really get tired of hearing "It works on Cummins" Just because some guy messed with his Dodge truck and got a little more Hp and probably twice as much black smoke. There may be more fuel to be had in this adjustment, but personally, I would not touch it unless it was on a flow bench and I could make proper adjustments.

GREASY_BEAST · #6 08-19-2008, 08:48 PM

Please lets be clear. The thing you are turning is not the delivery valve when you do this adjustment. The delivery valve is a tiny hardened steel device composed of two parts:

1) a guide
2) a valve

The guide/valve assembly resides inside a cavity above the IP Element, and is enclosed by an aluminium housing above, which the injector line attaches to, and sealed with a copper washer. The outside of this aluminium housing happens to be formed in the shape of a hexagon with 15mm between opposite sides.

This is how I see this situation:

When you loosen the two retaining bolts for a given element on top of the IP, and "turn" the 15mm housing (without it turning in its threaded hole), you are not altering the position of the delivery valve in relation to the element. You are altering the angular position of the element in relation to the rack. This has one possible side effect that I can see:

It allows a greater maximum fueling rate due to the fact that the helical sleeve on the element (the part connected to the rack) is favored more towards the full-fuel side, and therefore, when you move the rack towards full fuel, it allows more to flow in. I believe the same thing can be accomplished in a better way by removing the full-load limiter.

What I do not know is whether this adjustment will provide any further gains after removing the full load limiter. Due to the risk of throwing my otherwise extremely smooth-running IP out of adjustment, I will not be the one to find out.

I believe further gains can be found (in order of performance increase, high to low) by altering delivery valve shape, increasing injector orifice size, increasing rev limit, maximizing Torque Control adjustment, and removing rack limiter.

Please pick this post apart and prove me wrong wherever possible. We all can learn something here.

MTUpower · #7 08-21-2008, 02:00 PM

Quote:

Originally Posted by GREASY_BEAST

We all can learn something here.

This is the type of post that will move us forward and I thank you for your clarity. I'm not ready to try this either, until I get back to FL and can try it on one of my spare IP's, and then return the original one back on. I'm sure there are some folks here that may try this and report back with results. Perhaps at the next 24 hours of Lemons...

winmutt · #8 08-22-2008, 05:36 PM

The one person that has tried this has done so without EGT. BEWARE.

GREASY_BEAST · #9 08-23-2008, 10:46 PM

what you need to effectively assess the safety of this mod as far as the engine is concerned is a probe in each runner, because the adjustment adjusts fueling for each element individually. A similar thing can be done using the glowplugs as "cylinder temp senders", given a baseline calibration, but would you really want to?

h2odiesel · #10 08-24-2008, 10:08 AM

OK I'll come clean, I've been doing this adjustment for years. like other adjustments that are now public I don't like to post them in widely read forums because the uninitiated could cause them selves problems. I don't believe it will appreciably increase fuel delivered at full load. I've used it to smooth out rough idling after going through all other adjustments and checks. What is going on is you are changing the relationship of the barrel and its spill over port with the plunger and its helix. By rotating the barrels independently you are effecting cylinder balance. This is only properly done on a pump test stand. With some experience and technique you can achieve a good result and really smooth out the idle characteristics, or you can really screw it up. If I worked on your car you've probably had this done.

Bob

#11 08-25-2008, 06:25 AM

Quote:

Originally Posted by h2odiesel

If I worked on your car you've probably had this done.

Thats a scary thought unless you asked them if they wanted that done first. If not, its opening yourself up for some nasty lawsuits if somebody finds out about it and doesn't like that you did it.

h2odiesel · #12 08-25-2008, 07:08 PM

Everyone always left with a simle. It was almost always friends or family that said I wish my MB ran as well as yours. And I would say bring it over early Saturday and I'll work on it with you. I'd do the injectors and valve adjustment while they did fluid and filters. almost everyone needed motor mounts and air filter mounts. Then if they still had the shakes I'd adjust the balance wile running. FI you can bring yours by this Saturday

#13 08-25-2008, 07:50 PM

Mine runs great as-is with the rack limiter removed.

GREASY_BEAST · #14 08-28-2008, 09:11 PM

mine does have an odd imbalance... almost like a knock but not a knock... almost like overfueling on one cylinder only at idle.... maybe I should start fooling with those "do not touch on penalty of death" adjustments... I'll go through and re-pop all my injectors first though

h2odiesel · #15 08-29-2008, 09:56 PM

You definitely want to check your pop and pattern first. I'm sure you already have but make sure you don't have a tight valve too. Turning up the relative quantity of one cylinder without checking all the other possibilities first can mask and exacerbate your real issue. That said it is a valid procedure for a well informed self tuner.