The Stovebolt Site Forums The Parking Lot Big Bolts 1948 2 ton engine swap

I have a 48 two ton chevy with what i was told was a mid 50's straight 6. was wondering if there is a "more modern" straight 6 that would be a "bolt in" replacement that will have better oiling and a spin on filter. Thanks!

Depends on which mid-50s straight six you have. What are the casting codes and the serial number on the engine?

Here are locations of codes on some low-pressure engines.

Here are locations of codes on some high-pressure engines.

Follow up on Tim's question first.

But the simplest "bolt in" swap and the most bang for the buck in my opinion will be a 261. They are "more modern" than what your truck originally came with, but not a "modern" engine.

a close second choice would be a 235 with full oil pressure, likely you'll find you already have one.

Either engine can be adapted to full flow oil filtration (if not already) and use a spin on oil filter if you desire.

Grigg

How do you adapt it to full oil filtration or how do I know if it already is? And what did the 261 come in? Thanks!

There is a Tech Tip on converting/adapting to full-flow oil filtration.

1958-1963 USA 261 engines had full-flow oil filtration from the factory. If the oil line holes in the block are 1/2" NPT, it has full-flow filtration.

261s were usually available in large trucks, depending on the year (1.5-2 ton trucks, usually).