Which engine/trans/converter should I go with?

[AJH]

Hey everyone,

I have my 1984 square with a 355/th350/np208. I am currently running 33 inch tires and would like to stick with 33's and my current lift. I don't know how high my lift is I'll post a picture and see if you guys can tell me or if you can refer me to any reference guides that will tell me what to look for to determine my lift.

Basically what I am looking for is to make my truck something that is capable of being driven daily and getting decent gas mileage for a k10 w/ lift and 33's. I currently get about 8.5-9ish mpg freeway unloaded. I also don't know what my rear end gear is. When my speedo says 65 I'm actually doing about 62-63 per gps unit.

My goals are as follows:

-Something reliable enough to be a daily driver, though I won't likely DD it

- Decent MPG if I could get at least 12-13 highway that be good, more would be better

- A good amount of power, although not having experience with these trucks before I don't know how much power that would be. (the only thing I haul is firewood, mulch, dirt bikes)
-what would be considered decent power for one of these trucks?

So what do you all recommend? 5.3 swap? Stay carb'd? Rebuild my current set up? I can probably get $5k or so together for this (more if needed). I am not mechanically inclined enough to do an engine/trans/or transfer case swap. I will have to pay for someone to do the work.

 

[Skweegle89]

Just looking at that one pic, I'd say your running about a 4" lift if those are 33s. Your pushing it with the fuel mileage. You might squeeze another one or 2 out of it, but anything beyond that is going to be tough with a lifted 4wd and 33s. Im running a lift and 33s and a 350 and getting 4mpg at the moment, but that's carb related. What kind of carb are you running? Is there a specs sticker still in your glovebox? If so, it will have your factory gear ratio. That will make a big difference on your hwy mpg.

 

[marks86]

350 crate motor with normal bolt ons, with a hd700r4 and a np208 and you will be good to go

but if you wanna learn a lot and spend a lot.... 5.3swap with a 4l80e

 

[AJH]

I have 3.08 gears. The truck came equipped with a 305 and 700r4. The truck came with a Holley 600cfm. I don't know much about the engine. It is supposedly a 350 that was rebuilt 10,000 miles ago, along with the th350 but they both leak oil and trans fluid. Which makes me think I'd rather just start over with a known quantity than guessing at what I have.

I was thinking about going with this engine here and a 700r4: http://www.chevrolet.com/performance/crate-engines/small-block-350-290-hp.html

 

[rich weyand]

Don't go with the 350/290hp engine. The cam is from a 1967 high-compression 350, and is ill-suited to the low-compression heads. Above 3000 rpm it does great; below that it sucks. And the gas mileage will be terrible. BTDT. Get the 350/260hp engine. If you want, you can re-cam it before you put it in. Several good cams for that engine.

 

[Skweegle89]

If your going crate, I would go 383, but that's just me. In your first post you said you had a 355, then you said rebuilt 350. If it is a 355,
Why not just rebuild it and slap a quadrajet carb on it?


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[AJH]

I apologize, I was told it is a 355 but I have no way to verify this. I'm not terribly knowledgable on chevy engines or trucks in general, this is my first one. I am very open to suggestions, the gas mileage isn't the biggest deal for me because I can afford gas for as much as I do drive it. I really just want a truck that starts when I turn the key and runs reliably. I don't go mudding or anything like that but it will be driven in snow in the winter and in the woods when getting firewood.

If I get a rebuild is would it be worthwhile to get some better heads? And who makes good cylinder heads for a chevy truck engine? I'd like a smoother idle, as well ay suggestions on the cam? What about the intake and carb?

And thanks for all the suggestions and advice guys.

 

[rich weyand]

Here's one good, inexpensive setup that runs great and gets pretty good mileage:
GM 350/260hp crate engine.
Comp Cams 12-235-2 cam.
Edelbrock 2101 manifold.
Quadrajet carb.
Hooker 2453 headers.

 

[350runner]

I'd go LS if you have the money. Carbed engines really can't compete with modern tech.

Sent from the dust in front of you!

 

[rich weyand]

I'd go LS if you have the money. Carbed engines really can't compete with modern tech.

That's correct. Carbs are open-loop systems, and so are approximations to the correct fuel mix. Since too lean can cause the fire to go out, the error in the approximation is always in the too-rich direction. Fuel injection is a closed-loop system, where the mixture is constantly adjusted to perfect by the computer watching the O2 sensor.

More money gets more technology gets better results, in both performance and mileage. You pays your money and you takes your choice.

That said, it takes a lot of mileage difference to make up a big money difference up front, and a square-body K is never going to get great mileage. Lots of drivetrain losses and the aerodynamics leaves much to be desired.

My recommendation was a period correct, minimal cost solution that would meet your stated needs. If mileage is a big deal, and money is not a problem, the LS is a better solution.

 

[MadOgre]

Leave the engine that is in there. Get a FAST electronic fuel injection system that bolts in place of the carburetor and find a 4l80e and get the transmission controller from TCI

Any thing different then a th350 or 700r4 will require changing the input gear on the transfer case which requires complete disassembly of the transfer case. Or find a replacement transfer case with the correct input gear.

The th350 and 700r4 use a 27 spline out put shaft that mates to the transfer case. The th400 and 4l80 use a 32 spline out put shaft. And the adapters that go between the transmission and transfer case are different as well.

 

[MadOgre]

Most people are clueless when it comes to installing gaskets correctly. Get a gasket kit and redo the gaskets on the engine. I like the felpro blue one piece perma something gaskets for the valve covers and oil pan. Both can be had for pre 86 blocks

I have had my oil pan off three times and still using the same gasket with no leaks.

 

[Skweegle89]

I think I would leave it carbed, but that's just my opinion. Maybe because iv never driven a fuel injected square, but I like the idea of simplicity. But with most of your driving been in winter up north, you might be better off with fuel injection. If you will look on the passenger side of the block below the head and wrote the numbers down, then go to the back of the block on drivers side just below the head and get those numbers and post both sets on here, we will be able to tell you exactly what you have.


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[rich weyand]

Here are those ID locations:

You must be registered for see images attach

 

[AJH]

I tried looking at the numbers on the block but there are accessories in the way on the front and the firewall is too close on the back. I'll try looking again today and see if I can't get them. I don't think I want to go with efi right now, that will be a consideration after I get the truck's body restored better.

I was thinking about getting this engine set up here: http://www.jegs.com/i/Chevrolet-Performance/809/10067353K8/10002/-1 and a 700r4. Can anyone recommend a reputable place to buy a 700r4?