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360 stroker |
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Jeepoholic_Jake
AMC Fan Joined: Jun/23/2017 Location: Florida Status: Offline Points: 12 |
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Posted: Jun/23/2017 at 2:31pm |
I know the topic has been talked about but can't find much straight forward information about, anyways my buddy and I recently started a Mopar 360 into a Jeep XJ project, however me being diehard AMC (304 CJ, 87 YJ/87 MJ Jeeps currently and a build 99 XJ) I plan to pick up a Cj5 and swap A 360 in to compete with him and its been something I've always wanted to do. That being said, it will have head work, cam, pistons, intake, headers etc etc. My main question is, what needs to be done to run a 401 crank? I've heard just offset grinding and be done? Or bore the 360 to 401 standard, which I rather not do and stay around .40 over with forged pistons. also heard use Chevy 400 rods and pistons and many other ways. Can anyone share some information on what could and can be done? Thanks!
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DragRacingSpirit
AMC Addicted Joined: May/27/2009 Location: Mo Status: Offline Points: 903 |
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The 401 crank is a direct fit in the 360 block. The factory 401 block has the bottom of the cylinder walls notched a small amount. That is about the only thing I can think of you may need to do.
If you have the 401 crank and rods just order your custom pistons for the bore size you want. |
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Best 1/4 mile 8.99, 1/8 mile 5.71, 60 foot 1.27, no power adders
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Jeepoholic_Jake
AMC Fan Joined: Jun/23/2017 Location: Florida Status: Offline Points: 12 |
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I don't currently have the rods just yet, want to get everything planned out before blowing money. And yeah I also thought about the way of notching the block to fit the bigger 360 rods since the 401s are slightly shorter to fit without coming out
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tufcj
Supporter of TheAMCForum Supporter of TheAMCForum Joined: Jul/10/2007 Location: Watkins, CO Status: Offline Points: 4066 |
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You will need 401 rods, or have the 401 rod journals offset ground for even more stroke. 401s have larger rod journals than a 304/360. AMC v-8s are externally balanced, so you'll probably want to also start with a 401 flywheel and harmonic balancer. Since pistons will be custom, plan on having it balanced.
Bob tufcj |
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74 Javelin AMX 67 Rogue If you need a tool and don't buy it... you'll eventually pay for it... and not have it. Henry Ford |
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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A stroked 360 is easy. The 401 crank is a drop in, you just need custom pistons, which is normal and easy nowadays.
There are those that bore to a 401 size and that does work and has worked for a lot, but I have seen cracked cylinder walls in AMC race use and a 360 water jacket results is a reduced thrust thickness. The water jacket pattern creates a "scalloped" wall. So I do not recommend larger than the AMC recommended limit of 4.125" bore or .045" over. For sure in race use you will lose more power in loss of wall stiffness than you gain in a few cubic inches. But for street use it will make no difference. But you can also offset grind the 401 crank, and since you already have a custom piston it is not much more cost. A 3.85" stroke fits nice in a 401 crank, and Molnar has a 2" journal proper AMC offset 6" long rod specifically for AMC strokers. Makes for 412 inches. It's a nice package. I made a couple kits using a 390 crank stroked to 3.76" for a 360 for a 402, and it fit beautiful, no clearancing required, and the 3.85" should be the same. You would have to check, but even if notching is required it would be minor.
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Jeepoholic_Jake
AMC Fan Joined: Jun/23/2017 Location: Florida Status: Offline Points: 12 |
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Just so have I this straight, I can offset a 401 crank and still use 360 rods/pistons, right? Also a 360 bored .30 or so over with a 401 crank "should" equal around 392ci, correct? Thanks for the quick help guys, means a lot!
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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No.
Once you are into strokers stock rods and pistons are out. The increased stroke means you need to take some length out of the rod and piston total, or the piston sticks out of the top of the block. Add to that bearings are different diameters and widths, and piston pins are different diameters. It's all a mess. Some people adapt pistons from other applications, like a 400 sbc, but the valve angle is wrong, the piston pin diameter is wrong and you have to find a proper compression height to match your stroke and rod length. It becomes easier and cheaper just to have a custom piston made. And as I said before there are AMC stroker rods available.
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Jeepoholic_Jake
AMC Fan Joined: Jun/23/2017 Location: Florida Status: Offline Points: 12 |
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Thats what I was getting to about the 360 pistons is to have them made, not actual stock form
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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Yep a .030" over 360 with a stock 401 crank is a 391, close enough. But the 360 rod is a smaller diameter journal and a wider bearing. You could offset grind the crank and narrow the rod, but that is a cast rod. At that point buy the stroker rods and go over 400 inches. Another option would be a 401 rod and have a have a piston made at 1.500" CH and the big pin.
Using stockish components the only real workable one is a complete 401 rotating assembly in a 360 block bored .085" over. I don't really like it, but it has worked.
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Jeepoholic_Jake
AMC Fan Joined: Jun/23/2017 Location: Florida Status: Offline Points: 12 |
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Yeahhhh, heard about boring it out to 401 specs but rather not and stay 0.45 at most. Also didnt plan to keep cast rods, forged rods and pistons would be used.
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