amc360 crank

[kenlavigne]

Hi first time post need help I bought a 360 engine from a guy with the thoughs of putting a torque flite 904 behind it. the crank is machined flat with a pilot bushing sticking out of it there is no pilot flange for the torque converter pilot to center into. do I have a freak crankshaft or is there something I'am not aware of? The 304 that I took out of the jeep has a pilot hole for the torque converter pilot. am I in trouble here? please help.
thanks ken

[jeepsr4ever]

That's a 1970 only crank. You need to have it machined for an adaptor ring if you want to use it with a torque flight. ...or any available flexplate or flywheel. Flat flange is a dead end...good thing is your 304 crank is the exact same crank.

[tufcj]

That is a very early crank/engine. AMC used a Borg-Warner transmission until 1972, then went to the TF. Like MC says, you can have the crank machined to accept the TF. American Performance (www.oldcarparts.com) made an adapter that was about 1/4" thick between the engine and trans, and an adapter for the rear of the crank. The 304 crank is the same stroke and journal diameters as the 360, so you could swap cranks. You would need to have it re-balanced, and use the harmonic balancer and flexplate from a 360. AMC V-8s are externally balanced, so harmonic balancers and flexplates are each displacement specific. Swap them around and you will experience vibration.

What is the casting number on the heads? The 3196291-C is a very desirable 1970 only head. 71-73 was 3212993 or 3216090, both good heads but slightly lower compression.

Bob
tufcj

[kenlavigne]

Thanks guys called american performance I think he can help me with my problem. still can't figure out that I bought a engine with a one year only freek crank. the guy I bought it from was unaware of this and was running it with the flywheel just bolted to the crank. The engine doesn't have the 3196291-c heads it has 3231480-2 heads.

thanks agian for the help Ken

[tufcj]

Actually a 3 year crank in the 360. 70-72. In 73 they started using the TF trans and changed the crank. I'm not familiar with the 480 casting number, but with a 323 prefix they're pretty late heads. Obviously an engine that's been changed over the years. Glad we could help.

Bob
tufcj

[kenlavigne]

Also being the 304 and the 360 crank are the same will the damper pulley interchange????

[tufcj]

The pulley, maybe, the damper itself, no. Early engines used a 3 bolt pulley/damper, later engines used a 4 bolt pulley/damper. If they have the same number of bolts, then the pulley can interchange. There was also a different height water pump used on the early/late engines. The late water pump being shorter. Water pumps will interchange.

Bob
tufcj

[kenlavigne]

I sort of understand some what, but what changes if the two cranks are the same except for the rear flange when you put the 304 crank in the 360 block? The only differance in the two engines is the bore the balancing is in the flywheel/flexplate and the harmonic balancer so it seams that if you matched the flywheel/flexplate and the harmonic balancer that everything should work, our not!!!!!!!!!!

[tufcj]

The 304 and 360 cranks have the same main and rod journal diameters and the same stroke. Although the majority of the balance is in the harmonic and flywheel/flexplate, there is still some drilling done on the crank counterweights for balance. You can swap cranks, but I wouldn't do it without also having a professional balance job done. You can use a 304 crank with the 360 harmonic, 360 flywheel/flexplate, and 360 pistons/rods in a 360 block but it would still need to be balanced.

Just like there's a difference in the rear of the 70-72 crank, there are also 3 and 4 bolt harmonic balancers. 3 bolt was used 67-73, and 4 bolt 74-up. The pulleys (both crank and water pump) and water pump shaft itself are different heights and the pulleys won't align if parts are mixed. As long as you use a matched set, you'll be fine.

Clear as mud, huh?

Bob
tufcj

[kenlavigne]

so what your telling me is you can't go out and buy a new 360/340 crank and put it in a block with out having it rebalanced yes or no??

[tufcj]

Are you talking 360/340 Mopar? Completely different crank.


If you find a reconditioned AMC 360 crank and you're using stock pistons and rods, then it's probably close enough for a daily driver rebuild. I doubt you'll find a new AMC 360 crank without spending lots of $$$$. The AMC 343 has a shorter stroke. Some rebuilders sell them already turned with correct bearing sets. If you're doing a bore and adding aftermarket pistons, then I recommend a balance, as aftermarket pistons are usually quite a bit different in weight from a OEM factory piston. This is the same reason I would have it balanced if using a 304 crank in a 360. The difference in a 3.75" vs 4.08" bore makes the 360 pistons heavier.

My machinist balances the rotating assembly down to 1/2 gram. There are 31.1 grams in an ounce. My machinist charges $150-200 to balance. I believe it's worth it just because it runs smoother and will last longer.

Bob
tufcj