New to TDR and a new to me 1991 W250.

[GooberPyle]

This truck is a 1991 W250 with 400,000 miles on the clock that I bought from a dealer in Sparta, Tennessee. The IC'ed 12v has supposedly been rebuilt around 20-60,000miles ago, depending on who I talked to at the dealership and is backed by the Getrag 5sp. A pacbrake exhaust brake has been installed. It was originally a SRW short bed truck but has been converted to DRW and had a flatbed. Airbags were added to the rear suspension. I've done some poking around under the hood and somewhere along the line, someone has clocked the fuel pin, turned the star wheel to its max, and adjusted the smoke screw. I dont know if the power screw had been adjusted or not. It does have both a boost and an egt gauge. The turbo is non waste-gated and the ID plate shows that it is an hx35. Im assuming that this is an upgrade and that 1st Gens didnt come stock with this turbo. I don't plan to do much in that way of hopping it up - at least not in the immediate future. I may add a set of stage 1 injectors soon and maybe do the BHAF mod.

I do have a question - the highest boost number I've seen is 21. Does that sound about right?

 

[nick05]

nice rig. looks like my twin almost but yours is a dually.
you will probably play around with the pump a little to help mpgs and reduce smoke.
back out smoke screw and play with star wheel.
if you have a big exhaust housing. you're probably laggy or getting hot at times. all tunable.
pull a valve cover to make sure you have stiffer exhaust springs for that pacbrake too.
answering your question, it might only be 21 til you mess with the star wheel and even turn in the power screw. if the collar is on still, it hasn't been touched.

 

[GooberPyle]

Thanks, man. I've adjusted the smoke screw to clean things up a bit and the star wheel had been adjusted to its maximum prior to me. There is no collar on the power screw so I assume it's been adjusted, although I don't know how much. As far as the turbine housing goes, well....I don't know. The compressor says it's an hx35 but I don't know haw to identify the turbine housing. At WOT, I've yet to see over 900*. Nice truck BTW.

 

[nick05]

ok yeah if ghe collar is gone it's been tweaked. but like you said how fow from runaway??? won't know til you do it.
if you take a look at the exh. housing there's raised numbers on the casting. 12-14-16-18-21 are some of the possibilities.
your temps are actually low so you can put some fuel to it or get a fuel pin.
another thing you can do is bump the timing by the pump itself or jump a tooth.
either way you're set up good so far.

 

[GooberPyle]

Thanks for the housing info. I looked and didn't see any numbers. I'll look again in the daylight tomorrow. I should have mentioned in my OP that the timing has been advanced already, previous to my owning it. I'm gonna check out the power screw asap. If it does run away, will it be a gradual or quick RPM increase? I'll be sure and have a block to cover the turbo inlet.

 

[RWherley]

When they changed it from SRW to DRW howdid they do it? did they get a DRW rear or put spacers and duels on a SRW axle

 

[GooberPyle]

That's a good question and one I wish I had an answer to. It has a spacer but it only measures about 1/8" thick. I dont know why you would put such a thin spacer on. The wheels are not the coined dodge wheels either so I'm working on a way to truly center them. I think I've got that figured out.

 

[RWherley]

put up a picture of the rear hub with the wheels on but no hub caps.a friend of mine had a SRW axle with spacers to make a duelly it worked ok for a while but it caused uneven loading of the wheel bearings that lead to a catastrophic failure that ruined the axle spindle

 

[RWherley]

Looking at your air bag picture I think I see what was done but i need to see the out side of the hubs and if you could measure the distance from the spring seat to the edge of the break backing plate

 

[GooberPyle]

Here you go.

Not sure why this one posted upside down.

 

[nick05]

yes have a block of wood ready!
just go small increments.
rpms will hang after throttle release. so say you snap the throttle lever or even increase gradually but let off quick to snap back. if you're rpms hang a bit like not wanting to return to idle fairly quick, then you're about to the max turn in.
likewise if rpms don't hang after snapping throttle open, you can turn in more.
(sorry i can't explain very good) if confused ill try again

 

[RWherley]

Ok what you have there is a SRW axle, they used the spacer to increase tire to spring clearance, you can run that way for a while but don't load it heavy and it might not hurt to check the bearings for odd wear. if you decide to put a DRW axle on be advised there are 2 different ones, DRW pick up and DRW cab chassis, the pick up axle is wider then the cab chassis axle is but other that they are the same. The left pic is my DRW hub, the center one is my DRW pick up axle, and the right one is my friend's DRW cab chassis

 

[GooberPyle]

yes have a block of wood ready!
just go small increments.
rpms will hang after throttle release. so say you snap the throttle lever or even increase gradually but let off quick to snap back. if you're rpms hang a bit like not wanting to return to idle fairly quick, then you're about to the max turn in.
likewise if rpms don't hang after snapping throttle open, you can turn in more.
(sorry i can't explain very good) if confused ill try again

Thanks man. I get what your saying. I'll get around to fiddling with it soon.

 

[GooberPyle]

Ok what you have there is a SRW axle, they used the spacer to increase tire to spring clearance, you can run that way for a while but don't load it heavy and it might not hurt to check the bearings for odd wear. if you decide to put a DRW axle on be advised there are 2 different ones, DRW pick up and DRW cab chassis, the pick up axle is wider then the cab chassis axle is but other that they are the same. The left pic is my DRW hub, the center one is my DRW pick up axle, and the right one is my friend's DRW cab chassis


View attachment 97484View attachment 97485View attachment 97486

What is the difference between the SRW and DRW axle that makes the SRW axle prone to failure from running duals? I understand the SRW axle is shorter but does it have smaller/weaker bearings or something?

 

[RWherley]

The bearings are the same but the spacing between them is different, and the location of the wheel flang in relation to the bearings is different as well and grate for single wheels but loads uneven when duells with spacers are put on them

 

[GooberPyle]

Well it looks like I'm gonna be on the lookout for a DRW rear. Will the second generation D80 units fit?

 

[RWherley]

It will with some work, if i remember right the spring seats need to be moved and I forget but 2nd gens might have wider springs

 

[DVolk]

Do you have picks of how the air bag brackets are mounted to the axel ??

 

[GooberPyle]

I will post some up tomorrow.

 

[GooberPyle]

Here you go.