The Stovebolt Site Forums The Parking Lot Big Bolts 1948 4400 engine tranny combo advice

Okay,
I could use some advice on a new truck I recently bought. It is a 1948 4400 I believe. it has about a 12' dump bed on it. First I will lay out my goals and them hopefully someone can give me a little advice.
Currently the truck runs and drives but is a typically very low geared truck with worn out components that is not very road worthy. It has the original 216, some sort of 5 speed tranny with a pto to drive the hydraulics for the dump and a two speed rear axle.
My plans are to upgrade the motor and tranny to something more practical and modern, upgrade the dually to something with a 3.73 or maybe 4.10 range and upgrade the front axle to a shortened P30 with disc brakes. I also plan to shorten the dump bed (including the frame) to about an 8' dump so that it can be used more as a frequent driver. I won't need quite as much hauling capacity as it previously had, but I would still like to haul brush and debris to the dump etc.
My questions are:
What is a good engine/tranny combo, still retaining a pro?
What suggestions would you have on matching your recommendations with a rear axle?

In the past I have done a 5.3 LM7 conversion with a 4L80 in a half ton build that I was VERY happy with. I don't think a 5.3 will work for this truck (too small) and I have read that a 4L80 won't take a pto. So, I have read about the 4BT diesel conversions, but am not sure what would be a good tranny match with it, and I am not sure if that would be an economical choice. I have also considered the 6.0 liter and an 8.1 liter, just not sure if the 8.1 easily fits that original frame without some significant mods and not sure if the 6.0 would have enough power. Anyways, what suggestions do you all have for a motor/tranny combo that could be completed on a moderate budget, lets say under $4000?

My well worn original 283 and SM420 4 speed have plenty of torque for my '57 two ton, of course that's with the 6.17 single speed rear end but I would think a 6.0 would do very well. There were lots of ton and a half trucks in the '70's with 350's. Most of the medium duty's that I drove had 366 and 427's until we switched to Cat, Detroit, IH. If I was building a truck I wouldn't even think about an automatic just 'cause I'm old-school and like rowing the gears, the more the better.

Read in here about Grigg's conversion putting modern disc brake spindles on your front axle. A GM 14 bolt axle will provide a modern axle with higher ratios. Ratio depends on engine choice. A 292 Chevy would provide adequate power, that would still use your existing 5 speed and hydraulics. Need to move radiator fwd in core support. Best to find out what 5 speed you have with pictures and descriptions here. Could be Clark-Ci top cover, 3 shift rails; NP-540 series, Al top cover, 4 shift rails-

Of course, if really want a V-8, then other engine compartment changes required. Could still use Clark or NP trans.

16, 17, 19.5 or 22.5 tires and wheels are some choices, depending on axle selection.

Others will surely comment.

Ed

For your consideration, this is the combo I'm planning on using on my next project (3804, the 1 ton pickup).

1. Swap out bellhousing crossmember for a 54 or 55.1 crossmember that has the angled mounts.

2. Use a 55-72 v8 or 63-72 inline 6 bellhousing (whichever years had the angled mounts on the bellhousing). These have the standard gm transmission bolt pattern on the trans side, and the standard sbc engine bolt pattern

3. NV4500 transmission behind the bell (I already have an adapter plate made to bolt it to the bellhousing). You might not need to worry about this part if you want to keep your five speed since it probably has the standard bolt pattern that would fit on the later bellhousing

4. Cummins Chevy breadvan adapter (these are clocked 5 or 6 degrees, so your engine will look crooked) and a 4bt.

For a long time I thought using a 4bt was a waste of time, but then I drove a truck with one. It was a '54 1/2 ton, and it was a very good engine for that truck. The motor was coupled to a 700r4 (first mistake), and it had too big of a turbo on it (most of the time it wasn't spooled up because it was so big, but just running the truck on the motor provided plenty of power to move the truck).

The truck had the original frame, and none of the front sheet metal had been touched, so it will fit in the truck well. The guy who put it together had a custom front motor mount made that even used the stock front motor mount location on the 54 frame as well.

The bad: the truck vibrated a lot at idle, and the truck was noisy. I'm not sure how the vibration will play out in my truck. I've read you can bump the idle up, and that will take care of most of it. Once the truck was moving (the 54 I drove) the vibration did go away. My truck has always been kind of noisy, so I'm not too worried about the noise. I just use earplug on long trips.

I used to think the power would be too low because looking at the stock numbers it makes it look like a 261 would out perform it in everything except fuel mileage (10-15mpg vs 25-30mpg); however, you can always turn up a stock engine to make more power. I had thought that turning it up would drastically reduce the life of the motor, but a little digging over at 4btswaps will show that there are a lot of guys who have doubled their power output and have had reliable motors that don't blow up.

After seeing all of that, I'm sold on it. It will fit. It will have more than enough power. And I have an overdrive trans that will help with highway speeds. If the project ends up being too uncomfortable (vibration and noise), I'll just pull the motor, sell it (4bt won't loose any value provided you didn't get ripped off in the original purchase), and swap in a 292 (I never liked the idea of swapping in a v8 because of the fabrication needed since I like to keep the frame, suspension, steering, and bodywork stock where possible).

That's what I would do, though if you wanted to keep sparkplugs, a 261 or 292 coupled to an nv4500 is what I would suggest

Thanks for all the replies. What do you plan to pay for a 4BT? Here in Boise I have not been able to locate anything and looking at the internet, it appears that the cheapest used ones run $3500-4000K. I can pick up a reasonable 6.0 Vortec for about $1500. I already have experience with the Vortec and wiring in the FI, but it would be fun to try the diesel swap if I could find a reasonable priced one.

One can use an angled mount GM bellhousing with a 4500, just drill and tap GM bolt pattern in front of bellhousing, not use 4500 mounting bolt holes.

Ed

5 speed transmission ? Should have come new with a 4 speed.

Not sure what 5 speed is in it now, haven't investigated much yet.

Check 4btswaps. They usually have "reasonable" prices. That's one of the major downsides. I'm not planning on paying more than $2000-$2500 for mine. Those places on line are usually way above market. I played with fitting a 5.3 in my 6400, but it was a horrible fit. It could have worked. Anything can. But I was going to have to move the steering box (not just a little like with sbc conversions), and the stock exhaust was no where near fitting. I like factory frame suspension and steering, so I sold that ls motor and started looking into inline engines again.

One thing I also considered (but haven't done enough research on to know how much fabrication is needed) is taking the AD body and dropping it on a TF (55-59) frame. The light duty TF frames are basically two straight rails that are 34" wide all the way through with no drop for the cab which is pretty similar to the AD frames except you don't have the tapered frame rails in the front which are what make a v8 swap such a tight fit. I'm guessing the big bolt frames are set up the same way just with larger channel. With 34" between the front frame rails (outside to outside, inside to inside would be less of course) you could put anything up there you wanted if you made the mounts for it.