We installed a new Crane roller cam in a 340 block fitted with Magnum heads, which brings up another interesting benefit-with the better combustion chamber and port design of the Magnum heads, enthusiasts have been starting to retrofit them onto the earlier LA blocks by swapping the old-style lifters with the newer oil-through-the-pushrod type required to feed the Magnum heads valvetrain oil. Because all of Crane's lifters are the oil-through-the-pushrod types, you can convert to Magnum heads at no additional cost. But if you want to keep your original shaft-mount rocker heads, that's no problem either-just order solid pushrods and drop them in. Even though we did this installation on an engine fitted with Magnum heads, the procedure is the same, regardless of what engine you have. Follow along as we up the performance of our 340.
 This is all the break-in lube...  This is all the break-in lube required on a roller cam-regular motor oil. Jon poured oil on the cam as it was going in, then covered it again after it was in. Also keep in mind that doing this will add oil to the total amount in the pan, so make sure that you don't over-fill the oil pan before firing the engine back up. |  The thrust retainer for the...  The thrust retainer for the camshaft is retained, as per normal on the LA. |  Here's the whole secret to...  Here's the whole secret to putting Magnum Dodge Truck accessories on the front of an LA block if you want to run a 340 block in your truck like we are. There's no fuel pump eccentric on the Magnum engines, since the trucks are equipped with electric fuel pumps, and that's the biggest difference. This is the stock LA fuel pump eccentric, trimmed down to what essentially amounts to a flat washer with a flanged lip around it. The stock cam bolt is then used as per usual. This procedure is only used when running an LA in a new truck, otherwise, it's not a problem. |
 As long as the front of the...  As long as the front of the engine is off, it's always a good time to upgrade to a double roller timing chain, if you haven't already. Here you can see our modified fuel eccentric, too. |  And here's the moment we've...  And here's the moment we've all been waiting for-dropping the roller lifters in place. Know that the bridge connecting the two lifters must be inboard-against the block and facing the cylinders. |  These are magnum heads, so...  These are magnum heads, so they have individual stud-mounted rockers, and we're running Crane's roller rockers, shown here. If you've got shaft-mounted rockers, just install them as you normally would. |
 Drop the pushrods in place,...  Drop the pushrods in place, and make sure they're seated in the cup in the top of the lifter. All of Crane's lifters have provisions for oiling through the pushrods, regardless of whether the valvetrain actually oils that way or not. Because we're running Magnum heads, we needed hollow rods. If you're running early Mopar heads, just order the solid pushrods. |  Since these are hydraulic...  Since these are hydraulic rockers, valve lash is set by turning the adjusters 1/2-3/4 turns past zero with the lifter sitting on the cam's base circle. The plunger needs to be depressed past the snap ring about .020 inch. |  Tighten down the adjuster...  Tighten down the adjuster nut keeper, and you're done! Put the rest of the motor back together and go. There's really no run in time, because the lifters don't have to be mated to the cam like they do with a flat tappet. Terry was driving around right after he got the engine together and commented that the truck was running as hard as it had with nitrous oxide-now that's making power! |