Mailbag: Can I Overbore a 267 to Power My ’65 Chevy Truck?



Q: My father gave me a 267 Chevy small block that came from a Malibu. I’d like to drop it into my 1965 Chevy truck but I don’t think it’s a strong-enough engine.

I was planning to overbore it to a 305 and put in a Scat 4340 forged crank and H-beam rods. Then I’m going to add an Edelbrock Victor Jr. open plenum intake, a Holley Ultra Double Pumper 650 cfm car, and a COMP Cams Thumpr camshaft.

Do these parts seem like a good selection? I’m new to the automotive scene.

A: Welcome to the wrench-turning hobby! Just a warning: It’s addicting.

You may want to hold on to the 267 for a future project.

A stronger choice for your truck would be a stock 350 Chevy small block. You wouldn’t need to overbore it or add the crank and rods. You’ve picked a quality intake and carb, however they don’t operate in the best powerband for a truck application.

Instead, consider using an Edelbrock Performer intake manifold with a 600 cfm carburetor.

This combination will start building power at 1,500 rpm—which is perfect for your pickup. With the addition of your Thumpr cam, you’ll generate some serious power and be able to run on pump gas.

Have fun with your new hauler!

This is another in a series of weekly Q&A Mailbag sessions with Summit Racing‘s tech department, in which there are hundreds more. Click here to see them all.

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  1. Bart Logan says:

    “You may want to hold on to the 267 for a future project.” In other words, like anchoring a boat mooring. To bore for 305 pistons you’d need a .2736″ overbore…you’d be well into the next county by then.

  2. Cush Atkins says:

    A 5.3 LS could be had for the price of the parts mentioned A modern proven performer that will run well in stock form on modern gas

  3. rick ordiway says:

    Chevrolet didn’t make a 267cu in small block that I know of. but they did make a 265.

    • OnAllCylinders Staff says:

      Hey Rick, the 267 is kind of a footnote in Mouse Motor history: Chevy introduced it in 1979 and discontinued it in 1982.
      The 267 powered a handful of larger RWD Chevy cars, like the Impala, Camaro, and El Camino.
      It used the 350’s crakshaft, with its 3.48″ stroke, and had a 3.5″ bore.

  4. I would not use a Chevy 267 engine for anything except the pans and bolts if it doesn’t run. This was a bad idea from Gm and very low power.
    The only way I would use a 267 engine is if it runs and you need to move or drive the truck temporarily. This way everything would be wired up and ready to go for a fresh 350 or larger small block. All the external parts like the starter,alternator and powers steering pump and pump would work.
    I would not spend any serious money on a small engine unless you where restoring a original 283 engine vehicle and I would think twice before doing this.
    Chevy made lots of small Engines but if is not a 4 inch bore and no size restriction like a racing class go with the more common motors. This way if you pick a cam and other parts they where designed for the application.

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