Can I put an ’80s engine in a ’50s car?

Question:

I have an opportunity to acquire a late 1980s Chevy S-10 in a trade. I’m told it has a 4.3-liter V-6 and an automatic transmission, which may be a 700R4. It seems this combination would greatly improve the reliability and drivability of my 1955 Chevy 210 sedan. The 1955 Chevy has a 265 cid V-8, Powerglide automatic transmission, factory power steering and factory power brakes.

However, we haven’t found any accounts online of anyone having done this swap. What would be involved in making this swap? Would the original 1955 rear end hold up, or would the S-10 rear end have to be substituted?

I assume I could use the ECU, alternator, and power steering pump from the S-10, right? I would need to install an electric fuel pump with a return line. I’d imagine the radiator would have to be moved back, or an electric fan might be used, correct? Could the S-10 radiator and fan shroud be used? What about motor mounts, transmission support, and shift linkage? Would the transmission tunnel have to be modified?

Has anyone published a how-to in book form for this type of swap? I’ve also been reading with great interest your excellent series on doing a disc brake conversion, something I’ve considered for some time.

Answer:

Whether or not the 4.3-liter V-6 and 700R4 combination would “greatly improve the reliability and drivability of your 1955 Chevrolet depends on the condition of the engine and transmission that are presently in your car and the condition of the V-6 and 700R4.

While an engine and drivetrain from the late 1980s is obviously much newer and more advanced than similar parts from 1955, they are still more than 20 years old so don’t assume they will function like they did when new or nearly so.

That issue of functionality aside, you won’t face any insurmountable obstacles installing the later engine and transmission into your ’55 Chevy.

The 4.3-liter V-6 has often been likened to a small block Chevy V-8 with two fewer cylinders. The 90-degree V-6 was designed with the same engine-to-chassis mounting provisions, rear block face and bolt pattern, and accessory mounting features as the V-8.

The six is physically smaller than the eight so from that perspective it’ll fit in your engine bay without any difficulty.

If it’s in sound condition, the stock rear end in your ’55 Chevy should do just fine with the V-6. Depending on the year and some other variants, and assuming it’s stock, most of the earlier 4.3-liter engines were rated in the range of 130-165 horsepower. These are “net” horsepower numbers, so they’re right in the range of the higher horsepower V-8s available in the mid-1950s.

You can use the 4.3-liter engine’s external accessories but most will require some type of modification.

For example, in order to use the later alternator you’ll have to modify the car’s original wire harness.

You will need a high-pressure fuel pump and return fuel line if you operate the V-6 with electronic fuel injection. While most were equipped with fuel injection some of the earlier 4.3-liter engines came with a Rochester Quadrajet 4-barrel carburetor.