Dodge Engine Swaps For 1972 thru 198?

1975 440/4-speed with AC, cruise, a stock Thermoquad Carb, 1967 Magnum heads and a 1970 Magnum camshaft.

318 to 360 (The "LA" series)

Because these engines are so similar, this swap is generally considered an easy swap. However there are some very important differences that you should know.

But first, the things that are the same; You can use the same transmission/bell housing, rubber motor isolators, and all accessory brackets such as the AC, and alternator mounts. Also, you can use the same exhaust system and exhaust manifolds or headers. Many other items are interchangeable as well, such as the intake manifolds, water pump, distributor, ect. Note, the 360 and 318 used different sizes of 2-barrel carbs so the manifolds are different as well, thusly, do not use a 318 2-barrel intake on a 360 because the small 2-barrel carb must be used and power will suffer.

In Dodges, the truck/van oil pan is very different from the car version. The car pan holds 5 quarts and the truck small block pan holds 6 quarts. Also, a 318 oil pan cannot be used on a 360 or vice versa. The 318's and 360's also do not share the same steel motor mount brackets.

Probably the most important difference between 360's and 318's is that 360's are EXTERNALLY balanced and 318's are INTERNALLY balanced. This means that the 360 has extra balancing weight on BOTH the harmonic balancer and the torque converter/flywheel. You must use the correct parts here or the truck will vibrate itself to pieces.

Small Block to Big Block

This is getting to be a very popular swap. The information here can be used to swap from any small block (318, 340, 360), or even a slant six, to a Mopar big block elephant motor torque monster, this includes all non-Hemi engines, specifically the 361, 383, 400, 413, 426W, and the king 440. The 361, 413 and 426W are generally very old and are rare, so most swaps use either the 383, 400 or 440.

To swap from a small block to a big block requires a significant financial commitment. This is because nearly everything connected the engine is different. The big change is the transmission. The big blocks do not share a common bell-housing with their small block counter-parts. Therefore, if you have an automatic transmission, you must get a big block transmission or just the big block tranny case. Since both the small block tranny and big block tranny are both A-727, the internals are completely interchangeable if you so desire. Don't forget to get the big block kick-down linkages too!

If you have a 4-speed (NP435), and assuming that the new engine's crank is drilled WITH a pilot bushing, you "merely" need to find the big block bell housing and flywheel. The bell-housing isn't exactly an easy part to find, in fact, it's kind of rare. I have seen some online for sale around the $200 mark, also, recently I saw a "scatter shield" for sale in Summit Racing Equipment's catalog for just this application. It runs just over $300 I believe.

The big block will need the exhaust modified, or replaced. Mainly, you need a set of truck big block exhaust manifolds (the '62-'71 will not work) , or a set of headers. The manifolds are easier to find than the bell housing, but are often kind of expensive. Headers are easy to get, but I have never seen a pair of real high quality headers.

Just like the small blocks, the big blocks require a truck specific oil pan and dip-stick. These are easy to order from Mopar Performance through a dealer for just over $100. Don't forget to plug the "car" dip stick hole cast into the driver's side of the block or you'll have a big oil leak.

Believe it or not, the big blocks use the same rubber motor isolators as the small blocks, but big block specific motor mount brackets are required. You can probably get these from a salvage yard Dodge truck or Ramcharger with a big block for around $15-$20.

Obviously, you will need big-block brackets to mount your accessories. Parts from a donor truck are perfect, but brackets from a car will also work. The important thing here is the power steering pump location. Most car brackets will mount the pump too low to clear the truck's frame. The power steering brackets from a '71 or '72 car will work the best.

Stepping up to a big block brings even more concerns. Some Dodge trucks came from the factory with brake boosters that are very flat, but have a large diameter. These will hit the valve cover on a big block. The thicker, smaller diameter booster are required.

When swapping from a small block to a big block, the same radiator can usually be used, but bigger IS better. Small blocks have the bottom radiator outlet on the passenger side. Prior to 1971(I think) big blocks used a radiator outlet on the driver's side. In this case you could either use the later pump housing, which uses a passenger side output, or have a radiator shop modify your radiator to match the engine. Small blocks often had the radiator inlet on the driver's side, where the big blocks where opposite of that. If you have no AC you could probably just use a universal radiator hose. But if you DO have AC, you'll probably need the top tank outlet position modified.

One more thing, the wiring harness leading to the distributor, alternator, and temp sending unit will need to be extended. This is truly a bolt in swap, but many parts are required for a quality installation. If you take the time and effort to replace that small block with a big block, you won't regret it.