I've recently come into ownership of a very nice 79' chevy k20. What I mean by nice is that it only has 31k original miles, was kept indoors, and had the fluids changed every 6 mounths, and is equiped with the original fisher plow it was purchased with. The only downside is that it has a 350. This is the old fulltime fourwheel drive monster of the past. So far I've not been impressed by the 350's power. But i've only recently started playing around with diesels. I would like to know what i'd be getting myselve into to convert this to diesel. what type of engine, gearing, do I have to change the diffs, what issues will i see with backing plate and bell housing, i have an automatic trany will it still bolt up? I know that alot of people swear buy a cummings, but would a 6.2 chevy be easier. money is definetly an issue.... Thoughts?

 

the 6.2 would definately be easier to put in, it would bolt directly to ur tranny but without a turbo the 350 would have more power than the 6.2

 

a 4bt cummins has lots of power for pushing snow and will bolt to a turbo 400 transmission. 4bts are found in many bread/potato chip trucks and usually already have a turbo 400 bolted to them. 4bt is pretty easy to install and only has one wire to run. only other major consideration is that you will need a torq converter set up for a diesel engine.

 

I just had it ripped apart today, trying to get more power out of it. For one the throttle was only opening half way(the peddle was bent). In fact it was so bent, that the 4 barrels were not even opening. Definetly explained my lack of faith in the 350. Definitly has some more ***** now. I like the idea of the easier 6.2 but power is top priority. But if a 4lb cummins can bolt up to a turbo 400, that be easier, my neighbor may even have one laying around. But are there any bellhousing or clearance issues? Also assuming i put a decent turbo on it, how much horsepower, and torque are we talking about over the 350?

 

A lot of guys have done the 4bt to chevy swap over on the 4btswaps forum www.4btswaps.com

4bt engines come in several flavors but the most common is essentially a first gen 5.9L missing two cylinders. If you find an engine that came out of a bread truck it should either have the chevy automatic transmission adapter or the ford manual transmission adapter. As for fitting it under the hood, one of the members on 4bt swaps sells engine mounting brackets for both tilted and untilted engines (4bts were tilted about 10 degrees to the passenger side so the starter would clear the transmission adapter maybe?). I believe the engine will also fit without changing the firewall. If your truck is 4 wheel drive you will have to flip the oil pan around to clear the front axle. Powerwise the most common 4bt is rated at about 105 hp and 265 ftlbs of torque. I know this sounds kinda small but let me tell you about a ride I took in a 1970's 1/2 ton dodge powered by a 4bt. This was winter 07-08 in ohio. My friend and I went to pick up a 4bt for another friend. The guy who sold us the engine put a 4bt in his 1/2 dodge for plowing snow (originally powered by a dodge v8). He got his engine from a bread truck and decided to leave the chevy turbo 400 transmission attached when he put the engine in his dodge. While he was setting up our engine on a test stand the guy's dad took us for a ride in the dodge. All I can say is OMG that truck went like a scalded dog. Now since I have a cummins I knew right away his little engine wasn't stock but the only changes he made to it were switch the stock turbo to a hy35, put in a fuel pin, and install a 3200rpm governor spring. He used the truck to plow snow all the time and said he would do the conversion again in a heartbeat.

The guys over on 4bt swaps really know there stuff when it comes to this engine, and if you get serious about a 4bt you should really join that forum.

 

If it were my truck and I was going to do a cummins swap, I would put in a 6bt instead of a 4bt. The 6bt's are getting easier and cheaper to find. The 4bt's are still kind of hard to get a hold of for a reasonable price. The bread truck engine adaptor from the 4bt's will work on the 6bt's but they sit at an angle and look bad IMHO. I wouldn't do a 6.2 unless you can find a really cheap one and you can settle with low power.

 

member rubberfish has a 6bt 12 valver in an old Chevy...................maybe he will check in

 

I also have a 6bt in a 84 K20 but it has a Ford ZF5 speed and will utilize a NP205 tcase. I built the engine cross member, used 1st gen type motor mounts, and it fits in there pretty nice.

 

Thanks u guys. The funny thing is I just picked up a '76 nova that could really use the 350 outta my truck, so the diesel conversion is rapidly moving up on the priority level. though I would like to know what most diesel trucks are geared at. I'd like mine to be in the middle between torque and speed. (also is it easier to change the spider gears in the diffs or just swap axles from a dodge and monkey with the u-joints?)I have to admit the pleasure shutting down, any 4cylider riceburners that try to pass me in my truck has caused me to develop something of a lead foot. I also got to take a spin in a buddies truck. it was a '96 dodge duelly diesel witha 12valve cummins that he found, that was putting out 550 hp at the wheel. It was a little boner-inspiring.

 

What speed are you looking for? 3.73's in my '95 are great, right in between the 3.52's and the 4.10's. Although depending on wheel package you use, and if you still want to do plowing with it, the 4.10's would most likely be the way to go.