Gonna feel dumb on this one I think, but since I really am not sure, here goes...

I have a 69 Barracuda with a locked up junk 318. Looking for a donor motor, but here is what I don't know...will any 318 drop in? Truck? RV? Any year? I have a 7 1/4 rear end, so am afraid to go with anything bigger. I can find trucks with good 318's all over the place so this is why I am asking. Thanks for the help...

Dave in Colorado

You will need to change the truck oil pan and oil pump pickup over to a car oil pan and oil pump pickup. I believe you can use the pan and pickup off your 68 Dart's 318 (after cleaning it well) on the truck 318.

You will also need to use the left (driver side) exhaust manifold on the truck motor to clear the steering column.

You may also have to use the flex plate or flywheel out of your Dart, depending on which transmission/bellhousing you have.

If your locked up 318 is bolted to an auto transmission, you will need to pull the motor with the converter attached because you won't be able to remove the flex plate to converter bolts without turning the motor over. That could be a tight squeeze on a 68 Dart. Once the motor is out, you can reach all the flex plate to converter bolts with an open end wrench. Be prepared, the converter is a bit heavy and those 4 bolts are the only thing holding it in place.

Any mid 60's to late 70's car 318 or 360 shouldn't be a problem. Stay clear of some truck/RV motors, if possible, because of some issues mentioned above.

The pan is different on a 360 than a 318.
I don't think it was mentioned but you will also need the oil pickup screen off the old car engine along with the car pan. Not a big deal to swap over, once the pans are off. But, you will have to make sure the screen is clean/clear upon removing the pickup and before putting it on the donor engine.

It isn't a dumb question, it is a complicated question. I think any 318 can be swapped in but you might need to change some parts depending on the year of the engine as well as the vehicle the engine came from. The more modern the engine the more likely you'll have issues. Oil pan shape is one but you might also get into balance questions which might mean different dampers or flex plates. Pulleys can be different from year to year and application to application so don't get rid of anything off of your existing engine until the new engine is running and driving. Throttle brackets, transmission linkages, kickdown levers, etc. can all vary. Take pictures and look at things carefully.

So is the premise that any 318 block and rotating assembly from a similar year will work, as long as I transfer the usable oil pan, pulleys etc off my existing motor? That I can handle. I have installled plenty of engines. That doesn't scare me. I hope to find a drop in ready motor, but sounds like its safest if I steer clear of any truck engines. I never though sourcing a good 318 would be difficult. I can find big blocks all day long. I appreciate everyones input. I think it helped me alot. I did run some the fender tag on my Barracuda. Hoped I had a factory 4 speed....when I pulled up the carpet it became obvious that was not the case based on the hacked in 4 speed hump. Fender tag says 3 spd Auto. Gonna keep the 4 speed though. Thanks again everyone.

Don't be afraid of a motor out of a truck.
All 318s were internally balanced.

Later model 318's have air injection ports right underneath the exhaust ports that will need plugged. Drill, tap use set screws.

Mock up the exhaust manifolds with the engine on the stand, later heads wit the injection ports have added material that may interfere with the fit, you can grind down the extra to clear.

Timing cover holes in the block, early blocks have an extra hole later covers do no have, it will pee coolant. Double check that, it is almost covered, but it will pee anyway.

When did they change over to the aluminum water pumps? 69 might have still had the cast iron pump. The lower radiator hose was on the drivers side and the timing cover had the timing marks on the passengers side. I know 68 was this way but not sure about 69.

I don't recall, I want to say 70 was the first year of the aluminum pump. Not 100%, but these were things I ran into. Much easier to check and deal with on the stand than in the car.

Since you already have a locked up 318 in the car all you need is a 318 from 68 (LA Style / Post Poly Head 318) to late 80's early 90's (Pre Magnum) engine.

Swap over everything that doesn't match like the oil pan, intake, water pump etc.

Like people already mentioned the later 318's may have air injection ports in the heads. If the exhaust manifolds do not cover them, tap and plug them.

You can swap in a magnum but the intake manifold bolts go straight down and not angled to the face of the head. They require a different intake but even magnums have the ears on the block to bolt the old style motor mounts. Magnums will also take the old school distributors, oil pans, etc.

If you stick to a 318/5.2 motor use your existing flexplate and torque convertor. 360's require a different oil pan, an externally balanced flexplate, and motor mount bracket on one side.

Lots of good help here if you run into a snag.

OR an eternally balanced toque converter, which is how the factory did it. Be advised, Magnum 5.9's are also eternally balanced, but the amount is different than the LA 360.

As for the motor mount bracket, the 318 bracket is 1/2" wider than the 360 one, a spacer (1/2" nut) fixes that.

You missed the part where he said he had a 4 speed. He also stated he has a 7 1/4 rear end as well.

He would need a 360 balanced flywheel of the same diameter he currently has. Between the oil pan, the flywheel, and the 7 1/4, he has several reasons to be sure the "new" motor is a 318 and not a 360, and he has a pretty good reason to be sure it is not the Magnum 5.2 or 5.9 motor either.

Wait a minute. I know most hate the 318 and say " go right to the 360" (which aggravates me in and of itself) the OP asked about 318 swap in place of another 318, nothing was said about going to a 360..? Why so many "360" comments?

Pull a 318 out of F/J/M car. They're still around in yards. '85+ had factory roller cams. Not power houses, but will make for a very nice cruising motor with off-idle torque all through to 4500.