1983 G20 van build - looking for advice
 

I have a G20 van which I bought for DMV fees from a person who was going to junk it. Should I have done that? I don't know. It has a 350 small block engine. The last time (5 years ago from creating this post) it passed the smog test. I haven't tried passing the smog test yet. I try not to drive it at all, and I've only used 1/2 a tank of gas since getting it about 6 months ago :o Needed to use it a couple times to collect recycled materials and for school.

I live in LA, California.

Here is what a similar van looks like (mine is in much much worse condition):
https://i.imgur.com/LlC2GVA.jpg

I will start using the van a lot in about 4-5 months for construction work for a community garden for which other students and I have designed several buildings.

I have a mechanic coming in a couple days to look at the van. I figure that for now I should at least change the fluids in the current engine and try and get that engine running as cleanly as possible.

I am contemplating several options:
-Rebuilding the engine. Trying to get the current engine to run as efficiently as possible.
-Buying a modern, small displacement (3.5L vs the current 5.8L) fuel injected gasoline engine (used) alongside a transmission and putting it in the van. After that, turbocharging it so that it makes enough torque to pull the van.
-Buying a diesel engine (used) and going the bio-fuel route. I live in a place with plenty of mom-and-pop restaurants so I think they will be fine with giving me their oil.

How much do you think each option will cost me? My budget is around 3-4 thousand I would say if I work hard for the next 4 months. I am a student so making money is difficult.

Which of those options is realistic? How much would each cost? What would you recommend? I would like as much information as possible on what you think I should do.

My end goal is to produce as little NOx and greenhouse gasses as possible. It is not to save money. Having said that, I have no experience working on cars, but I'm decent with my hand and I think I can learn.

Swapping a different carbureted engine for a carbureted engine was simple - find/make engine & transmission mounts, adapt the driveshaft, figure out something for the speedometer, build/adapt throttle linkage, ditto for the transmission linkage, figure out radiator and heater hoses, gas line, electrical wiring, a few other things, and done. One long weekend with a friend to help and shop facilities at hand. And lots of small parts.

Swapping a modern computer controlled fuel injected engine is about ten times the work, much of that figuring out how to get around the nonexistent BCM.

I suggest working with what you have. Minimize total driving, grille block, tire pressure, air dam, wheel covers, and get a wide range fuel air ratio gauge. Then work with the fuel air ratio, your driving habits, and maybe some carburetor tuning. Also the transmission shift points. If you get really ambitious, try swapping in a five speed to get the benefits of a manual transmission plus an overdrive fifth gear.

You will be amazed at how much you learn just by maintaining what you have, plus the improvements I suggested.

I am new here but your post grabbed my attention. I work on cars and such as a hobby, not sure why, and had a van similar to yours. I replaced the engine and rebuilt the transmission in it. Unfortunately I was never able to put it on the road and eventually traded it for another vehicle. In my opinion vans are a nightmare to replace engines in. The engine comes out the front of the vehicle so all that has to come out, radiator, AC core, grill. Also you mentioned you are not experienced working on cars and a student. Doing what you are planning will take much time and if someone else is doing for you much money. As far as engines go if it is fuel injected a 4.3 litre 6 cyl motor would fit and may still give you power needed. The problems come in when dealing with engine management controls. I live in upstate NY and have emission regulations for inspection which I think you have to deal with also. If the van has underlying problems it may turn into something that you are constantly pouring money into. I have often thought of going to diesel but would buy something that is diesel. I am unfamiliar with wiring diffrences between them but know there is quite a bit that would need to be changed. Not to discourage you but I think leave it as it is and run it until something better comes along.

What if I swap the 305 for a newer v6 262 (also carburated)? A 5.8 to 4.3L reduction?

Is displacement not the crucial factor?

A manual transmission would definitely be awesome, especially in a carburated engine when you can disengage the engine while driving downhill. I would assume that would save tons of fuel right?

Regarding the grill block, would that cause any overheating problems in a van like this?

What kind of mileage do you think I could expect?

What about the carburated diesel option?

@cmyers What engine did you replace yours with? Did you also have a 305 in it? I will have a mechanic come look at it in the next couple days. If I were to replace it with something, what would be the best option? Will passing the smog test be harder once you replace the engine?

When you said underlying problems, what problems did you mean? All I can think which is in the van is an engine, transmission, and suspension. If I replace the engine and transmission, what else is there to worry about?

Mine had a blown 305 and I was able to get a 350 from a friend's station wagon. I think mine was a 1985 and was fuel injected. I said 4.3 because they put them into full size trucks so figured that would give you the power you needed. There are also many aftermarket products for the 4.3 and will fit your current transmission. If the van has just a 3 speed transmission you could put a 700R4 transmission giving you overdrive. Other issues I was thinking of would be rust, especially fuel lines, brake lines, exhaust. Being in New York that stuff is not fun to deal with. Not sure how much of the emission system you need to have hooked up or if there is a cut off year for emission inspection. Probably just swapping over to an aftermarket fuel injection system would boost your mileage and power. I was once a carburetor only guy but now am seriously thinking of converting my Chevele to TBI. What did you mean by the radiator block?

Do you think this is a good option?
https://i.imgur.com/WVtn7fv.jpg

What kind of transmission would you recommend for it? I think a 3 speed auto is a really bad idea, and I'd prefer a manual. I know you recommended the 700R4 but isn't it just a 3speed? What is overdrive? Overdrive is the transmission allowing the engine to rev higher right?

If I change my 350 to that 262 will it get better mileage?

Or if I am going this far is it easier to just swap for a diesel and try biofuels?

Or is this a better option? No idea what engine this is yet.

https://i.imgur.com/Wcfpb56.jpg

Is making it run on biofuels possible? Turbo diesel sounds awesome to me.

The 700R4 is a 4-speed. And 4th gear is an overdrive gear, meaning lower engine RPM. Overdrive means the output of the transmission will be spinning faster than the input.

Or will this do the trick? It looks like the transmission is included in the engine?
https://i.imgur.com/onuEq2u.jpg

Since it's from a chevvy will it fit G20 mounts do you think?