AMC 401 Flywheel Question

How do you identify a 401 flywheel from a 304/360, and how do you know how to orient it? I would expect something to match the offset hole on the crank flange but its not there. I was givin this with my 401, but didnt pull it off personally. The clutch marks are 11" in diameter. I thought 401s had 10.5".

 

The J trucks ran the 11" clutch

 

OK, I was told this came out of a 77 wagoneer. Did they run 11" too?

 

You sure the pattern is symmetic? I would assume there's only one orientation possible.

I recall that either the 10.4" or the 11" clutch will fit. '74-80 FSJs 360-401 all use the same clutch, according to the parts book. Only the 304 is different.

 

Take a look at the pic, I can see where the old hole was, but how does one know where that should go? I understand you can tell the difference btw flywheels depending on where the 1" weight is, but what determines where 12 o clock on the flywheel is?

 

I have yet to put a flywheel on, the motor is on a stand, and wont fit with a flywheel...are you saying the flywheels are drilled crank specific?

 

No, I'm saying that the bolt pattern may look symmetric, but when you put it up to the end of the crank, it won't be. I think.

 

Ok, that might solve my orientation problem, but I've searched the forum for a solid answer to counter weight position for identifiation, and cant seem to find one. The only mark on the wheel is a nameplate screwed in with L287 just above the weight.

 

If it's an AMC flywheel, it should have a number like 321 2655. If it's an aftermarket flywheel, then you can maybe match the number to the Crown number ... I think they make the factory-style (cast) replacement flywheels. They have a website.

Maybe it's Omix-Ada that makes them, but I think it's Crown.

If you have your 304 flywheel, you should be able to stack them up and see what the orientation will be when the flywheel is on the engine.

I don't think anyone can predict what the orientation will be from some principles - the whole point of the externally balanced engine is that the balance is specific to that engine, and you'd have to know how the weights on the crank are balanced in order to predict where the weight should be on the flywheel. Not easy to figure out without spinning the crank in a balance machine.

 

How do after market flywheels work for AMC? If the weight position is a guess for each engine, how do they mass produce?

 

Mmm. They don't guess. The flywheels aren't different from engine to engine, only between displacements. A 304 flywheel is different from a 360 flywheel which is different from a 401 flywheel etc. etc. However, you can replace one 401 flywheel with another 401 flywheel. The flywheels balance out differences in the design of the 304 vs. the 401, for example, not the differences between individual engines.

When I wrote "that engine" I meant "that engine design."

 

LOl, after doing some CSI tricks, I found a cast number in the rust. 3197219-C. With the casting number as 12:00, the weight is a 4:30. The wieght also has a letter designation L287.
I looked at this, since it was referenced in another post, but I still cant be 100% sure.

http://www.matadorcoupe.com/enginespecs.htm

I measured the crank flange recess, and its 4.65. This all matches up with the 3rd version of the flywheel, except mine has the "C" suffix, and the counterweight is not at 9:30,its at 4:30, LOL This is getting frustrating. The weight is also 3/4" deep, also matching version 3.

 

Go to bulltear.com. It's for AMC only

 

My 401 factory flywheel also has 3197219 cast onto it. It will only bolt up one way.

 

Take a look here. This might be helpful. I did a google search for AMC flywheel identification and found lots of other stuff out there too.

http://www.amcgremlin.com/AMCml-archive/msg01433.html