hypereagle's AMC V8 Mounting Kits

[shanebo]

If im able to tackle my current 4.0 efi head swap on my 83 with out royaly screwing it up I may just have the guts to try tackling a v8 in my 86. Theres just somthing about the exhaust note of a v8 that makes ths conversion so darn appealing.

[captspillane]

Did anyone figure out how compatible the flywheels are between a 304, 360, and 401? How is this data given? I'm imagining a value in decimal inches of the distance of the neutral point in relation to the center.

I heard a rumor that the flexplate on my 401 could go on my 304 and the flywheel on my 304 could go on my 401 without any noticeable vibration issues. The rumor is that the 304 and 401 are nearly identical external balancing while the 360 is abit off.

One reason I ask is that I see new flywheels advertised to fit the 401 that also say it will work behind any 304, 360, and 401. It makes me question the interchange knowledge of the company selling the flywheel.

[carnuck]

They bolt on, but a 401 would vibe with a 304/360 flexplate. The amount of weight is slightly greater as the engine size goes up. I drove a 304 with 360 flexplate and I could feel the vibe but others couldn't

[hypereagle]

All the weights are exactly in the same position.  The larger the displacement the heavier the balance weight. Also greatly depends on stroke versus bore. Dont remember which one was more significant.
Have seen a 401 with either a 258 or 304 flywheel. It did have a severe vibration.
 I once. Ran a 343 With a 290 flywheel. It too had a significant vibration.

  To Captain Spilaine
  Taking note of your knowledge and ability which are both very good. Im going to make a suggestion which I do not think will hurt the flex plate or counter weight. Use what I am about to suggest with your own discression.
  My suggestion would be to weld/build up the counter weight until the engine does not vibrate when revved up.
Don't let the heat sink into the flex plate and every thing should be good. Again caution! The flex plate is fairly hard and should not heated up too much. 

When I did my flywheel for my 360 SX4 I used the 258 flywheel. Got the dimension of the counter weight from a 304 flywheel. Used 4 different thicknesses of steel tacked them together and drilled them. Using a carbide with cutters on the end in a drill press cut a flat surface in the proper position of the flywheel as if I was using an end mill. Positioned the weights so I could center mark the flywheel for drilling and tap.

Once in the car bolt in bolt off until one of them (used only 1) worked. It worked very well. A combination of 2 or more weights could have been used. I lucked out with just 1.

[hypereagle]

Again to Captain Spillane. I welcome any comment coming from you either good or bad as I do thank you for the good comments I have received from you. Every thing you post has been very informative.

  Thanks again.  Terry.

[captspillane]

Thanks Terry! You've got a very good thing going here.

I understand exactly what you did with your flywheel. I’m going to try a new unit before attempting to modify an old, but I do also believe that a flexplate can be modified without cracking if you are careful and preheat properly. "All the weights are exactly in the same position" is precisely the answer to my question that I was looking for. I cannot add weight without being confident where to add it in relation to the center point. I was concerned at the possibility of a clocking difference. I’ve actually found evidence online that some V8 flywheels did have their weights clocked differently but that won’t be a problem when adding or deleting weight from one V8 displacement to another. If you start with a V8 version you will already have a weight present to indicate the proper clocking.

I believe now that the rumor I heard was dead wrong. It said that a 304 and 401 were very close and a 360 was very different from the other two. In other words the rumor said that a 360 with a 304 flywheel would vibrate much more than a 401 with a 304 flywheel. I believe that rumor to be officially dead wrong because earlier in this thread Mav asked for flywheel weight numbers from an AMCA member. I presume he got them when he wrote this quote, "I've learned that the 304 and 360 flexplates are so close (down to the tiniest fraction) in balancing that they will work for each other."

Likewise you wrote that it was either stroke or bore that had a much greater difference than the other. I believe Mav is right that a 304 and a 360 have nearly the same balancing because they have exactly the same stroke. My 401 has a much greater stroke and bore than either.

As it stands I would be comfortable taking my 304 flywheel and putting it on a 360. That’s probably not a noticeable difference. It doesn’t help me much because I have a 304 and a 401 right now. I don’t consider the 401 to be compatible with any other.

My conclusion is that I need to match balance a 4.0 flywheel to the old 401 flexplate. The 4.0 flywheel will be lighter and a quarter inch thinner than an original 401 flywheel. The extra inertia of the heavier flywheel is helpful in a full size truck but my Eagle is too agile to need it. I also want to eliminate the need for my NV3550 to T5 bellhousing adaptor. It won’t be necessary with the thinner 4.0 flywheel.

That will also open the opportunity to install an integral bellhousing NSG370 6 speed later. Those are slightly weaker and age with less grace than the NV3550, but they do shift considerably nicer. Both are much stronger than an AX15, which is also much stronger than a T5.

[AMCKen]

Does anyone have pictures of the balancing weights on the different flexplates? Somewhere I have one of a 401 plate. 304 and 360 plate pictures should be easy to get.

[68AMXGOPAC]

I may have a 304 plate , I know I have a 401 and a 390 , wich may be the same as a 401, not sure on that.
I think I have flywheels and flexplates for the 390 and 401.I should look them over to match.

[carnuck]

I have a 304 plate (for TH400. 727 and 9xx flexplates are 4 bolts for the converter) The "notch" it's hanging from is all the way open on 6 cyl ones so all three openings are equal (zero balance). On 360s, the notch is smaller. On 401s, the notch is almost fully closed, or a weight is added to a 360 one



Link to AMC forum with the other pics http://theamcforum.com/forum/flex-plate-id_topic4832.html

[akamc]

Does this kit relocate the front axle in any way? Will it work at bone stock suspension height? I'm considering this for an Eagle I may put a lift on. I'm thinking about 3" but would want the axle mounts lowered to avoid joint binding. Are the lower arm mounts incoperated in this kit and could they be lowered as well?

I did an SX/4 a few years ago with a 4.0 and a 3" lift with spacers on top of the springs and the front axle mounts lowered about 2". It worked every well for me. Sold it and I'm now thinking about another SX/4 but with a V8 swap this time.

[captspillane]

Generally a 3" lift isn't possible as you described. More accurately you lifted it an inch or two at the most from stock height, which is easily an inch or more higher than where most Eagles sit today with their antique coil springs. A true 3" lift has been accomplished by others here on the nest and it was much more involved.


The steps you took to lower your front axle 2" on your last car are the exact same steps you'd have to take with this kit. The kit is two sets of engine mounts and another set of plates that weld onto your existing crossmember. The engine mounts include an intergrated piece of metal that sticks down pretty far for the two side bolts on the side of the axle. On the original 258 this used to be accomplished by two pieces of metal instead of one, the metal plate at the engine mount and another long thin strip of metal that bolted to the rear of the engine on the driver side. Keep in mind that the oil pan is bigger on a V8, so Terry had to position the front axle nearly touching the oil pan to keep it at stock height.

[hypereagle]

Hey thanks again.

[uglywilly]

hyper, if U R still selling the 360 motor mounts, I've got money burning a hole in my pocket!



Brant
[email protected]
Call or txt. 931-220-0368

[IowaEagle]

All of his mounts will accept all GEN II and GEN III AMC V-8's.

[vangremlin]

hyper, if U R still selling the 360 motor mounts, I've got money burning a hole in my pocket!



Brant
[email protected]
Call or txt. 931-220-0368

You may want to send him a direct message for a quicker response.  He hasn't been in the Den for a couple months.  Good luck!