Hello All,
I have got a 1995 Chevy Silverado K1500 with the 4.3L Engine, and I am Interested in putting the 350 engine in. What would be involved in doing so and what would I have to change to do So? Also if anyone has any pointers as to where to get the engine and other parts from that would be greatly appreciated.
Thanks In Advance,
Sneaky Bananza

 

I'm no expert, but for starters you'll need a harness, computer, mounts, exhaust headers, and possibly bigger rad + fan. Are you doing the tranny too?

 

I would start by looking at wiring diagrams, parts diagrams, and repair manuals to get a good idea of which components (and their locations!) are the same. You might only need to extend a few wires to get connections to reach instead of getting a new harness. You will most likely need a new ECU. I'm finishing up swapping a TBI 5.7 into a '94 C1500 that had a TBI 4.3, but since this is the older TBI version, and not the Vortec I don't want to comment too much on that. I'm pretty sure you won't need a new transmission as my '94 C1500 has a 4l60e, the 5.7 I bought came with a 4l60e, and my '98 Tahoe with 5.7 has a 4l60e. The 4.3 frame mounts to motor mounts are a giant pain to remove, and the V8 motor mounts are thankfully "slightly" less of a pain to install. You will need new motor mount bolts/nuts, as well as the longer bolt/nuts that join the engine to the mount.

Where to get an engine? This can be very complicated. What's your budget? How mechanically inclined are you? Do you know how to inspect an engine if it has been removed from the vehicle? Will you rebuild it? After thinking about those questions and deciding on an answer, these are your options:
-Junk yard
-Craigslist, facebook marketplace, etc.
-Remanufactured

Suggested repair manuals:

1995 Light Duty Truck Manual
https://www.ebay.com/itm/1995-Chevro...EAAOSwotFbP3kM

Haynes
https://www.ebay.com/itm/Repair-Manu...YAAOxyg7xSaIV7

Alldata if you prefer subscription based
https://www.alldata.com/

 

I thought there would be more electrical work going from six cylinders to eight, but I guess these are primitive engines.

Nevertheless, the V8 will be putting out more power. I know that GM reinforces certain areas in the 4L60e when putting it behind a V8 to make it stronger. The torque converter could be different as well to accommodate a different stall speed. Is the bolt pattern the same, or will you need a different bell housing?

How are the driveline components going to handle the additional torque. Will you need a larger drive shaft? Upgrade ujoints? Stiffer suspension to handle the additional engine weight?

 

I might be wrong, but I think the amount of electrical work involved is most dependent on whether or not someone sticks with the correct OBD version and engine components. I did have to extend several plugs so they would reach the correct components, which can introduce problems later if they weren't properly done. From my extremely limited experience, I went with a 5.7 that didn't have additional things like an air injection pump because my 4.3 didn't have it. As far as suspension, drive shaft, etc, I'm not sure if they are really different, but do suggest comparing part numbers and seeing if they are engine specific, or chassis specific. As far as I can tell the two 4l60e transmissions I have sitting in the garage have the same hell housing bolt patterns, but the torque converter dust shields have different bolt patterns and numbers. In my mind, it wouldn't make financial sense for Chevy/GM to have specific suspension and driveline components for the 4.3 and 5.7, but I'm no expert. I'll be sure to update everyone in my thread if this becomes an issue though.

 

I am Planning on doing the transmission because it has 221k on it and to me it makes sense that if I'm in there to do it.

 

heavier duty transmissions are the 4L65 and 4L80.

Or you could go for newer more efficient ones like the 6L90 or 8L90, but they might require more electronics. Not sure.