Ok, file this under the “why the hell would you do that” section.. but suppose you found a nice 340 engine (GUILTY AS CHARGED!), and you wanted to replace your Magnum engine with it. Well, you can… and it’s pretty easy if you know what you’re dealing with.

Let’s start with the block. While these look like they’re the same, there’s a few differences you need to know about. First, LA blocks used a flat-tappet hydraulic cam and you can swap it out with a roller cam, but your lifter bosses are different, so you can’t swap those out with stock magnum lifters. So you’ll need to either run a hydraulic cam and lifters, or a roller cam with retrofit lifters.

Second big difference is the engine mounts. The LA Engines used a mount that ran bolts through a set of ears on the block, but the Magnum engines had bolt holes tapped into the block. While there are kits out there for 92-96 Dakotas, we got the “tough shit” treatment when we called about a kit for the 98. But a few minutes welding the mount-to-engine bracket to the stock mount solved that problem.

The other difference has to do with the crank trigger. Magnums have two tapped holes in the rear of the block to mount the stock crank trigger, but the LA blocks don’t. You can either drill & tap your own holes, or make a bracket to bolt to the back of the block.

As far as the LA heads, intake, timing cover, water pump… just shitcan them and use your stock Magnum parts. The hot thing to do nowadays is to swap the LA heads with the better-designed Magnum heads. The Magnum rockers will work, but you’ll need pushrods and lifters that have oiling provisions since the Magnum heads don’t oil through the block. The stock Magnum timing cover will work, but check the clearance between it and the cam. After that, just bolt your water pump pulleys, and accessories on and you’re set.