1994 DS4-DB2 Conversion 4974 Pump Qs

[Rafedial1]

Hello, I came looking for help!!! I have a rare 1991 DB2-4974 Marine Injection Pump and am using to replace my DS4-5068 pump. I am converting the truck to mechanical injection. I already have the correct injection lines for the truck and well as the necessary brackets and other items. The pump installed ok and centered on the timing sprocket and the lines fit great. Here's my problem, the mechanical pump has a shaft sticking out from the front of the injection pump (front of engine), it has a spring which allows it to push in and out. What is this for? My electronic pump does not have this, it only has a nut and threaded stubby shaft. The problem is the mechanical pump's longer shaft sits against the timing cover when installed and the spring in it compresses. So the mech pump sits flush with the timing cover, but wont that longer shaft rotate with the pump rotation? If so is there a difference in the timing cover or timing sprocket for a older 6.5L diesel? I am also looking for the ONE injection line extension. It is an extension used on only one injection line to help align injection lines. Anybody happen to have one? Any help is greatly appreciated. Thanks in advance.

I will send some pictures if needed.

[Rafedial1]

thought some pictures would help....

[john8662]

The piece on the front of the DB2 is a damper, keeps tension on the driveshaft for the DB2, keeps seals in check, because they can be just pulled/worked loose out of the pump.

Anyways, this piece will contact a flat spot on the back side of the water pump backing cover, that attaches to the front of the timing cover, just below the oil filler location on the cover.

You'll be fine, no difference in the timing gear.

As far as the little adapter for the injection lines, some pumps had these on them, because one injection line is shorter. It's technically a timing adapter, though I have not seen what actually attaches to that fitting to check timing. Do you need one? I have a few of them I think... You will only need one, for the shortest line. I'm drawing a blank on which cylinder it goes to, either 1 or 3, none of my rigs have this fitting though... Not all sets of lines use these, perhaps yours don't need it.

J

[Rafedial1]

Yes, I would like to get one of those fuel injection line extensions from you, A.S.A.P. I have Paypal. Also looking for a spare 4911 pump. Got any other 6.5L parts for sale?

Are you 100% sure the Db2 pump shaft that contacts the inner part of the timing cover is OK? Does it or does it not spin with the injection pump? Is it lubricated or does it just NOT TURN?

Also for the DS4-DB2 Conversion can I use the single thermostat crossover with the H.O. water pump? Or should I just modify the double thermostat crossover I already have? Note: I pyshically can't weld aluminum....

Thanks John for the help!!

[DmaxMaverick]

He's 100% sure. Me too. It turns with the shaft, or it doesn't. I've seen various mileage pump covers with only an indent, no indent (no evidence anything was against it), and indications it spins. No problems in any case. There's plenty of oil slinging around there, so lubrication isn't an issue, in any case. As John said, it's only a "damper". It keeps the pump shaft from chattering back and forth, and the spring pressure is very light.

You can use the HO water pump with the single stat. But, I don't think there's any gain w/o the higher flow rate of the dual stat. A worthy upgrade, IMO.

[Rafedial1]

Good to hear that!

Should I use this 4974 pump I have or a 4911? I am running new, not reman, not marine, just OEM injectors. Does the injection pressure of the marine pump match the oem injectors?

The HX35W turbocharger is already bolted up with ext wastegate along with finishing up the front mounted intercooler. This is a pretty extensive build. I am not the most knowledgeable about diesels, more so with LSX, SBC/BBC.

I should prob start a project thread...

[DmaxMaverick]

Either pump will be OK. The injectors determine the injection pressure, not the pump. The pumps only determine maximum volume, timing, and event duration. The pump pressure is only a factor if it is worn to the point it can't produce enough pressure to pop the injectors. Not a problem for any of them with OEM injectors.

[Rafedial1]

Alright, if I am going to use the dual thermostat crossover in combination with the DB2 pump, the throttle bracket contacts the water crossover. I have the DB2 conversion manual and have attempted a couple of my own brackets. I just can seem to get it to work. Does anyone have a modified throttle bracket? or be willing to make one for me?

[DmaxMaverick]

www.peninsularengine.com may have what you need. Give 'em a call.

[Robyn]

A standard 93 throttle braket will work by slightly trimming the one side and then welding a little piece of rod into what is left to stiffen it a little bit.

I have seen this done a couple times and it works great.

The dual stat crossover does cause a couple issues where it gets too close to some things.

I may use a dual stat unit on my 92 conversion but that will depend. The little 6.2 probably wont care if it has a dual or not.

Good luck

You might drop "Rat Man" a PM and maybe he will send you a pIx of his bracket.

best

Robyn

[john8662]

Is your engine stock c/r or lower? For a STD compression ratio engine, I'd stick with the 4911 (turned up) and the HX35 set at 17psi boost intercooled at the most.

The FMIC hanging below is manditory for sure, and works very well. My '95 K2500 suburban saw 95 degree intake temps with the sender mounted in the manifold itself (that is, ahem, mounted to the cylinder heads, where it's hot). This was with the hanging ATA, 3" in and out 24x12x3.

That was @20psi boost from a hybrid holset unit (not hx35) tho.

As far as the spring assembly for either the 4911 or 4974, it does rub/spin against the tab on the waterpump backing plate, but as Dmax says above, there is oil there to supplement this device. It's all good ;)

J

[Rafedial1]

Is your engine stock c/r or lower? For a STD compression ratio engine, I'd stick with the 4911 (turned up) and the HX35 set at 17psi boost intercooled at the most.

The FMIC hanging below is manditory for sure, and works very well. My '95 K2500 suburban saw 95 degree intake temps with the sender mounted in the manifold itself (that is, ahem, mounted to the cylinder heads, where it's hot). This was with the hanging ATA, 3" in and out 24x12x3.

That was @20psi boost from a hybrid holset unit (not hx35) tho.

As far as the spring assembly for either the 4911 or 4974, it does rub/spin against the tab on the waterpump backing plate, but as Dmax says above, there is oil there to supplement this device. It's all good ;)

J

The truck as it sits is a 1994 C2500 and has a 1997? up 506 block that was a crate engine installed back in 2000 or 2001. Engine was freshened in 2005 with bore, hone, re-ring at a reputable diesel machine shop. 60,000 miles since then and no troubles!

21.5:1 comp ratio.

All below not complete

HX35 from a 5.9L h.o. cummins. external wastegate,
Marine 4974 pump reman, replacing a troublesome 5068 pump/electronics
130 gal water pump, dual stat
Racor 90 pgh Fuel Filter/Water Sep/Heater
The intercooler a 26"x8", 3 in/out core A/A.
plan to run 12-15 psi max to keep the block together
4L80E will get a HD2 shift kit

That AM General P400 longblock sure is nice!