4BT into '92 F250

underwood tire

underwood tire

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Sep 4, 2007
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Thought we'd post up about our 4BT conversion.

We have a '92 F250 service truck here at the shop we make our road calls in. It's a 2WD with a 351 Windsor in front of a ZF5 tranny. We found a donor bread truck with a good running 4BT in it.

Worked out very well. No major problems. Peter at South Bend built us a clutch and we kept the ZF5. Power is about the same as the 351 but we're hoping for MUCH better mileage. We know how to get more power but we want to see what kind of mileage she'll get stock first.

For more pics and a blog on it check it out here:

Tackle Box Cummins Retrofit - Underwood Tire and Repair

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Sweet-e1297884876690.jpg
 
Nice swap. Should last a very long time. Much better than a gas motor. What kind of mileage does it get?
 
I'M AGAIN IT!!!!! lol

Sweet build up Joe. And also going by the pics, I'm glad to my theory of you being the slave driver type boss that does nothing but hover over the workers and crack the bull whip every chance you got was proven wrong lol.
 
well our first adjustment was the fuel. we gave it more fuel (about a turn and a half) we also went about a turn and a half on the anaroid. driving around town was still at 20 mpg but on the interstate we went to 18. we are leaving the fuel settings the way they are and we are adjusting the timing............. stay tuned
joe
 
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man i want a 4bt in a reg cab short bed s-10 pickup it would be a fun little truck and get good fuel mileage.
 
SKYNYRD said:
man i want a 4bt in a reg cab short bed s-10 pickup it would be a fun little truck and get good fuel mileage.
Click to expand...

we went to the scales the other day and we were at 6620lbs. the truck does good for that amount. an s10 would be a wild ride :woohoo:
 
Two things I'd recommend changing for mileage-

Lose the ZF. The gas versions have the same ratios as an NV4500. The M5R2 is just as strong or tougher with ratios better suited to the 4B.

Use a dodge PS/vac pump, lose the extra V-belt, lose the serp belt idler pulley entirely. The same belt tensioner will work fine, just needs a new hole drilled in it's mounting plate to clock it differently to tension on the ribs of the belt. Plenty of engines left cummins this way. They rev quicker at lower fuel rates and don't have belt tracking issues.

Those things combined with 3.54 gears and a properly tuned engine fueled to 150+ HP will deliver a pretty solid 23-25 average in that truck, higher 20's freeway.
 
When we get another vacuum pump/power steering pump in I'll do that. Maybe I can put the A/C compressor up there.

We have noticed the gap between 3rd & 4th with the ZF5 is way too big.

Last tank:

312 miles
13 gallons

24 MPG!

We're getting there!

Joe
 
we would like to. when one comes along it will be in there. you know how it is, it is hard to stop:ft:
joe
 
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