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Discussion Starter #1 (Edited)
I bought this truck with a broken crank, 6.5 diesel auto trans 4L85 155k mileage? I already have a 4bd2tc engine and trans. What do you guys of vast knowledge think:D
 

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Chevy/Isuzu

Sure,it will work.Have you seen www.isuzudieselswapper.com?You use his adapter with your Chevy auto.You will not have a speed demon (not that it ever was) but you will have an economical rig, deliverig about twice the fuel mileage and it will last twice as long as the 6.5.
 

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Sorry I don't know enough about the Isuzu engines to tell you exactly which version I had, but I used to have an '87 Chevy Tiltmaster (same as the NPR) rollback ramp truck that I used to travel from northern NH to Mass. to pick up vehicles. It had over 300k miles and was very abused when I got it, and it still served me very well. It was no speed demon (as was mentioned above), but it got the job done while barely sipping fuel. The two biggest loads I hauled was a 1-ton dually Chevy dump truck on the body for about 120 miles, and it handled it fine. I also hauled two vehicles back from Mass., a Jeep Comanche on the body and a Wrangler on a trailer behind the truck and even coming through the White Mountains, it was able to keep up with traffic.

I sure wouldn't hesitate about putting on ein a 1-ton+ truck. I have a friend with a 3500HD rollback who wants to replace his tired 6.5, and I suggested that he use a 4bt. He only uses the truck around town and to haul junk vehicles 20 miles to the next town, so the 4bt should work out well.

Jim
 

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speed

Jim, those are all good stories regarding the abilities of this engine.I read with interest all of the posts here that discuss enhancing the power of our engines,but honestly, I wonder if tweaking these things too far is worth the risk of premature failure.I have a '86 NPR flatbed that will do 75 mph and is very quick getting up to 60 mph( and that is with a cumbersome 5 spd gearbox) I think with the chevy auto it would be even quicker.The 4bd will never be a cummins 6, but to call it "light-duty" is laughable.My two cents.
 

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The little Isuzu in action:


I liked the manual trans in my truck, except the fact that the complex shifter linkage was very worn out. I would never put an auto behind a diesel...its a waste of a good motor...but thats just personal opinion.:dustin:

Jim
 

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Discussion Starter #7
Which Trans Should I use?

Isuzu , Chevy thats in the truck (4L85le? computer controlled), or older (non computer controlled) Chevy 700r4? . Why can't the Isuzu be made to work without a computer?
 

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auto

I agree with you,Jim, in general about manual vs. auto, but the 5 speed in our trucks sure would benefit from a o/d.I didn't realize how much drag the big tall box was until I took it off and put on a flatbed; it is much quicker and faster now and the mileage is much better, but it could easily be 20% better with an o/d.
 

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Jim, those are all good stories regarding the abilities of this engine.I read with interest all of the posts here that discuss enhancing the power of our engines,but honestly, I wonder if tweaking these things too far is worth the risk of premature failure.
I'm running 20psi boost in mine at the moment with fuel turned up and driving by the EGT gauge. Backing off at 750 deg C. Has done about 3000km being treated this way and seems to love it still.

Next thing on the list (it's been on the list for about a year) is to get the intercooler hooked back up.

Strangely the Isuzu 5sp transmissions we get here are overdrive models (MSA-5P, MSA-5G, MSA-5R etc). Could be worth checking which model you can get. There's a sticky with gear ratios and model numbers in it.
 

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Trannies

I've owned/parted 10 NPR and I have never seen a o/d 5 speed.I think that the thought was that these trucks were overwhelmingly used as city delivery trucks over here and that the o/d was not needed. I've thought of trying to find one in Oz, but I think adapting the old rod shifters to a new configuration might be a major stumbling block.
On another note, Dougal did you ever find out if these transmissions can interchange between a 4 and a 6?
 

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On another note, Dougal did you ever find out if these transmissions can interchange between a 4 and a 6?
There's a massive size difference between the 4BD1T and 6BD1T gearboxes. You could fit a 6BD1T box to a 4BD1T with some creative adapting. But the other way around would be inviting trouble.
 

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gear

There's a massive size difference between the 4BD1T and 6BD1T gearboxes. You could fit a 6BD1T box to a 4BD1T with some creative adapting. But the other way around would be inviting trouble.
Yeah, the reason I ask is that the 6bd1T, 6 speed trannies did seem to make it to our shores and having 6 gears to use would really suit the 4 nicely.
 
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