1990 non intercooled cummins questions

[Leif Churchill]

Hi everyone. New to the forum, and have some questions. I am looking at buying a 1990 D250 with a 727 auto. Supposedly rust free, with only 159k kilometers on it.
I have never owned a non intercooled truck, and usually like my 5 speed manuals.
As i understand it, the 727 auto trucks all came with 3.07 gears in the rear. Can anyone confirm this?
I know these trucks have the baby H1C on them, and that it is a bit restrictive. I have an HX35 in real good shape sitting. It has a 12cm hot side. I don't have any issues swapping turbos, but curious if anyone has any experience doing this and could tell me what kind of performance it had? Fuel will most likely be left stock. Just wondering if it would be worth letting the motor breath more in stock form.
This would be a daily driver truck, with possible light towing once in a while.
What can I expect to be different from my intercooled truck?

 

[EDankievitch]

I had a 89 for 11 years. By far the best truck I ever had. The 727 was paired with the 3.07 rear. With no overdrive you needed that tall a gear to get any speed out of the truck.
I installed the BANK’s intercooler kit when it came out in 1991. I ended up installing a smaller turbo housing after screwing up and installing Bank’s fast turbo kit. The factory housing was way faster at spooling up. I did a lot of very heavy towing way back. Over 18,000 lbs. the truck was rated for 12500 as I recall. The intercooler helped with high temps. I also up graded tha radiator to Th the later cross flow type. Great article in the TDR around issues 2-6 about how to do it. I still have the cast I take tube from that truck. I also turned up the fuel screw and the star wheel for mor power off the line.
11 years and way over half a million miles. I never should have sold her. I saw it last year still running. My advise go over everything. Do a fluid change. And have someone that know what they are doing adjust the bands on the transmission. And install the Borgison steering shaft.
It’s a great truck if given half a chance she’ll give you great service.

 

[Joseph Donnelly]

I'd leave the turbo alone, until it needs a rebuild, and then keep the stock type since you will keep stock or near stock fueling. The wastegated turbos, like the 12cm housing HX35, are about 1.25" longer and would shove the downpipe into the heater box. If you just have to get more spool up, get a 16 sq. cm. non-wastegated housing but realize that separating the exhaust housing from the main housing could be challengine if y ou are not very experienced, due to heat warpage and rust over time.

 

[sdeeter19555]

I own a 90 w250 that is more or less a toy and daily driver...727 and 3.07 gears, I have no complaints and no regrets about it not being a stick.

The 727 is stout enough...I adjusted the bands myself (not difficult) and adjusted the kickdown linkage and bumped the line pressure (also not difficult). I also added a Dorman transmission pan for a 48RE (gives another quart or more of fluid capacity). Unknown miles, but the trans is likely original and still feels good although I know the bands are well worn and the trans was abused prior to me. My next experiment will be type F fluid or John Deere Hy-Guard to see if it makes it a little more driveable with the non-lockup converter.

The non-IC deal, I rebuilt the H1C using a Turbo Labs kit and the truck has a Denny #2 fuel pin installed by the PO, I get just a puff of black off the line and it clears right up...truck is no slouch. I'm not sure if it has a governor spring (I think it does) and the tamper-proof hat is still on the fuel screw. With that said, under as much of a load as I can get unloaded, it pushes 1100 degrees and about 22 psi of boost...I thinking runs out of fuel, but it is still plenty driveable and doesn't "roll coal".

This is on a truck with 35 inch tires...

I agree with what was previously said, if it looks like it's in good condition, change all the fluids and drive it.

 

[HPSimpson]

Welcome to TDR an valuable resource for Ram/ Cummins trucks!

 

[Leif Churchill]

Thanks everyone for the replies. Turns out it is an Arizona truck, which I think is probably a good thing. It has towed a 5th wheel but it sounds like they can take a bit of punishment.
On the subject of the turbo, I've done a few turbo swaps and experimented a bit, just with intercooled trucks. Was just curious if it would be worth the half hour it takes to change.
Getting more pics of it in the next couple days which should help with my decision. The idea of owning it is now growing on me more every day. I may have a problem. Lol.

 

[Leif Churchill]

I'd leave the turbo alone, until it needs a rebuild, and then keep the stock type since you will keep stock or near stock fueling. The wastegated turbos, like the 12cm housing HX35, are about 1.25" longer and would shove the downpipe into the heater box. If you just have to get more spool up, get a 16 sq. cm. non-wastegated housing but realize that separating the exhaust housing from the main housing could be challengine if y ou are not very experienced, due to heat warpage and rust over time.

I've done the hx35 swap before, and am fully capable of doing any mods. Just curious if it's worth it if I have parts sitting. Or would it feed too much air and leave me having to crank up the fuel? I used the 12cm housing on an intercooled truck with a getrag 360 and 4.10 gears. Went back to 21cm H1C, hx35 ran 10 or more psi at 60 mph and used more fuel. Maybe I didn't tune it right.

 

[Joseph Donnelly]

The main problem with the wastegated housing is the length; your downpipe is close to the heater box already and there is no room to push it back 1.25". 21 cm2 is too big and builds boost too slowly I tried it along with other size housings, 12, 16, 18.5 and found the 16 to be best for any HP where the HX35 is enough turbo.

 

[NIsaacs]

The main problem with the wastegated housing is the length; your downpipe is close to the heater box already and there is no room to push it back 1.25". 21 cm2 is too big and builds boost too slowly I tried it along with other size housings, 12, 16, 18.5 and found the 16 to be best for any HP where the HX35 is enough turbo.

I have a direct turbo mount Pac Brake on my '91, no clearance issues at all.

 

[RSchwarzli]

Welcome to the funny farm!

Have had my 1990 for 20 years now. Have played all of these games!

HX35 is great. What I did was left the H1C snail bolted to the downpipe and exhaust manifold, and then replaced the front assembly. Makes it quick and easy. Now the turbo outlet is a bit different so would need a reducer. Trying to think back how I did that. Havent run that setup in 15 years..... That setup I would run to about 33 psi before the EGTs would start being just too much. But for not towing much honestly, I wouldnt bother changing the turbo. The H1C will support about 250 HP/25 psi.

Yes. All 727 trucks are 3.07.

Not much to expect different. They are great engines. Your CPL is 0804.

Where in Canada are you?

Robert