273/318 Swap

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scott657

scott657

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I am looking to replace my tired 273 in my 64 Barracuda /4 speed.
From the threads I have read this is pretty much a bolt in swap. I just want to make sure of any pitfalls I may encounter before I advertise for the 318, I realize there may be some water outlet issues etc. I have no problem with that. My main concerns are motor mount, exhaust clearance, oil pan and clearances.
Any advice is welcome. And as always
THANK YOU FABO
Ill be looking for a good running 318/273 in the Socal area
 
Make sure to confirm the crankshaft register diameter on the 318 if you're mating it to the 4 spd. 65'
 
The mounts, oil pan & pickup are a direct swap to the 318. If you get a later model 318 (~'74 and up?) you may have some clearance issues with the driver's side exhaust manifold at the #7 exhaust port. The oversized mounting pad for emissions (air injection ports, all of which will need to be plugged, BTW) can cause some conflict with the manifold "downleg". A bit of grinding (don't get carried away on this, you'll be sorry) or an extra thick exhaust gasket; or combination of the two may be necessary. Earlier teens don't have this issue.
Passenger side is no problem, but you may need the 90* oil filter adapter from the 273 to clear it if your 318 doesn't already have one.
Make sure your crank is drilled for a pilot bushing, or you can use a later Dakota roller bearing after making sure the relief is deep enough.
 
Oh, and a '70 and later 318 has the water pump inlet on the passenger side, as opposed to the 273 being on the driver's side, necessitating either a new radiator or a timing cover/water pump (and pulley set) swap from the 273.
The later pump is also 2" deeper than the 273 pump, which can cause some clearance issues.
 
scott657 said:
If there is an issue with this, what is the solution?
Click to expand...
The 318 crankshaft may have to be drilled for the input shaft of the early 4 speed. Compare it to the 273 both depth and diameter. 65'
 
Plymouth 65 said:
The 318 crankshaft may have to be drilled for the input shaft of the early 4 speed. Compare it to the 273 both depth and diameter. 65'
Click to expand...

Isn't there also a thinner wall bronze bushing you can use?

I know there is a roller bearing and insert you can use from the Magnum engines that fits in the torque converter register on the crank. You just have to cut down the input shaft on the trans. My dad runs this set up on his 440/833 and my TKO is set up the same way (except the TKO doesn't need cut shorter).

More info here.
Pilot bushing for 4 speed swap

Mopar Performance Pilot Bearing
 
scott657 said:
If there is an issue with this, what is the solution?
Click to expand...
Not an issue if the 318 crank pilot hole is deep enough. If you don't get a finished crank (pilot hole machined for a manual trans pilot bushing) just use the Magnum pilot bearing. Your flywheel will fit just fine. Depending on blocks sometimes motor mount brackets need to be modified to fit. It's a matter of how many bosses are on the block and where they are located. Most 273's have three bosses on each side with a bracket to match. Some 318's also have three, but, a different three, so brackets have to have ears cut and added as necessary. Some later blocks have all four bosses.
 
I did this exact swap in my 65 Barracuda.Use all the 273 stuff like water pump and timing case cover,the 273 motor mounts and exhaust manifolds.Chances are the 318 will not have the hole drilled in the end of the crank to the final dimension for the pilot bushing so you will either have to turn the outside of the bushing to fit or find something else that will work.I think there is some kind of roller bearing now I did mine back in the very early 90's when there was little interest in A bodies and parts were not really available so I turned mine down and had no problems at all for 12 years after and it was still fine when I sold the car. You will need a 68 273 flywheel or you'll have to have the center hole of the 65's opened up to accept the end of the crank or maybe not I used a 71 318 and all my 65 stuff just went right on . Other than this stuff it's a bolt in job using the 273 bell and the 65 A833.

DSC03252a-.jpg
 
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