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K1 rod install |
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74Bubblefender
AMC Addicted Charter Member Joined: Jun/29/2007 Location: The AMC form Status: Offline Points: 2589 |
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Keep in mind we are relying on chinese quality you must go through all the rods to ensure they are right in every aspect. The same can be said about any aftermarket rod or OEM rod from another motor. AMC kept a very tight tolerance on rod specs but you will come across strange things if you take apart or build enough AMC V8s.
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We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564 |
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ghinmi
AMC Addicted Joined: Apr/04/2010 Location: Grand Rapids MI Status: Offline Points: 978 |
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My K1s worked great out of the box. Any chance that we could each take some measurements to see if our rods are slightly different?
Also, what does the chinese forging have to do with these issues? The machine work is done in the USA. |
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1975 Cherokee S - Turbo Hemi stick shift autocross/drag race/street 9.97 @ 140.4
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Steeno
AMC Apprentice Joined: Aug/24/2011 Location: Ottawa/Canada Status: Offline Points: 88 |
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Ghinmi, I would be glad to take some measurements to see if there are differences. It may be that the difference is in the bearings. It's a long shot, but it may be that your bearings had a little more clearance, or may be your crank radius (journal to counterweight) is different.
If you look at the pictures via the link to the Wannabe post provided earlier in this thread, you can see his bearings clear the radius. Mine are much closer to the outside of the rod. Otherwise, this picture shows clearly the bearings are skewed to the outside of the journal, which is the opposite of how the stock rod carries the bearing. FTR, when I ran into this problem, I did a lot of measuring and comparing the K1 to the stock rod, trying to figure out if I was missing something. Except for the position of the bearing in the big end, all the measurements were identical. To my mind, it looks like the manufacturer skewed the bearing in the wrong direction....essentially backward. The Wannabe thread suggests the reason for this is because the notch for the bearing tang would interfere with the rod bolt hole (the notch in the cap is more the issue than the notch in the rod). I've dropped off rod bearings at a machine shop to have them narrowed by 0.080 (80 thousands) -- which is roughly equal to the clearance the stock rods provide to clear the radius. Narrowing seems to be an easier process than chamfering. As Skeown mentioned, I'll be certain to keep the forum posted. The forum has been invaluable in understanding the problem and finding a solution. |
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Steeno
AMC Apprentice Joined: Aug/24/2011 Location: Ottawa/Canada Status: Offline Points: 88 |
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Okay, so I had the rod bearings narrowed by 0.050 (fifty thou). I had originally instructed the machine shop to take 0.080 because that was the approximate gap the stock rods allow for. But after cutting the first one, we agreed 50 thou would work fine. Narrowing, instead of chamfering was much easier for the shop, as they were able to place all the bearings on a table grinder at the same time. Chamfering would have to be done individually and would require blocking to hold them in position (or clamp them in an old rod perhaps).
I picked up the bearings this morning and was able to quickly check the fit. It clears the radius easily. In fact, I could have gotten away with 0.030. The side clearance on the rods is 0.016. So it all should go together fine. My only worry is that there is some vulnerability in reducing the bearing surface area (reduced oil pressure, perhaps?). But as has been pointed out in posts and discussions, most feel that narrower bearing will have little impact. In any case, I'm hoping my motor will hold together well. I can't imagine I'd be running more than 400 HP with a 5500 to 6000 redline. The idea here is that I'm not asking too much and there will be no ill effects of the reduced bearing. We'll see ...thanks for all the input. I'll be completing the engine assembly in the next week. But I won't be able to test it in the car for at least a month as the Hornet is waiting for control freak suspension among other upgrades and changes. At this rate, I'll be glad to get it going before the "season" ends and it starts getting cold again...and the snow flies. |
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SKeown
AMC Addicted Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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If narrowing the bearings .050 concerns you, then the width of the bearings NASCAR run would terrify you, and they turn 9000 rpm all day long. Make sure there are no burrs on the machined edges and forget about it. We now know .040 would be safe in the future. Hopefully K1 will position the location tab correctly now.
SKeown
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Javelin74
AMC Nut Joined: May/18/2010 Location: Scottsdale Status: Offline Points: 398 |
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I got a set of K1's on the way for a 360 build. Is this a common experience for their 360 and 401 type rods? In either case, I'll keep an eye out. Since the 401 bearing end is larger, I'm hoping this isn't common on their 360 rods.
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Steeno
AMC Apprentice Joined: Aug/24/2011 Location: Ottawa/Canada Status: Offline Points: 88 |
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Javlin74,
I don't know that this issue is common exactly, only that a few have had some trouble. Others have had no problem (see posts in this thread). What I think is clear from all this is that the K1's differ from stock in terms of orienting the bearing in there "saddles" in both the cap and rod. In my case, it seems that the bearings interfered with the journal radius. I suspect others didn't have similar problems because of a possible the difference in bearings -- some bearings may be narrower or orient differently in the saddles etc. I really can't say as I have little experience with different brands of bearing (and this is my first AMC build). I don't know if it is the same for 360s. I know the rod journals are a smaller diameter. But I don't know if the journal width (and the "thickness" of the rods) is narrower. The 401 journal width is about 1.8" with each rod being about 0.9 and change thick. I finished the rotating assembly install, torqued etc. All the clearances check out and everything spins freely (as much as is reasonable with the pistons installed). It's a relief that I was able to find a reasonable solution (with much support from forum members...thank you :)). I'm ready to finish the assembly. Thanks again to all. |
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77 Hornet Hatchback 401 four speed.
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BassBoat
AMC Addicted Joined: Aug/29/2008 Status: Offline Points: 1719 |
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Just a follow up question, do you have the brand or part number of the bearing you used? Getting ready to assemble a short block with the K1 stuff, or I should say mock up and see how much the rod needs to be narrowed and how much the bearing needs to be narrowed. I think the bearings in the crank kit are Clevite, I have to double check. The other car I sponsor is running hard in its second season with no issues but I did not assemble the engine and the owner did not modify the bearings or rods. Thanks,
BB
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Steeno
AMC Apprentice Joined: Aug/24/2011 Location: Ottawa/Canada Status: Offline Points: 88 |
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Bassboat, regarding the brand of bearing I used, I've looked back in my notes, and for some reason I did not record the brand (in writing). I think I thought I could remember...and of course I can't for the life of me recall. Apologies, that was an important detail I over looked. At this point, the bottom end is buttoned, so I don't have any real way of checking.
It is important to note that many on this forum have not had this issue when installing K1 rods, and it is not clear why it showed up on mine (and at least one other in a cross posting on this thread -- see the "Wannabee" link posted further up). You may find you do not have any issues and it will be an "out of the box" install. I hope that's the case for your build. Cheers. |
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77 Hornet Hatchback 401 four speed.
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Javelin74
AMC Nut Joined: May/18/2010 Location: Scottsdale Status: Offline Points: 398 |
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I'm about to put that set of K-1's I got into the 360. I'll post up my results. I have a set of Clevite .001 bearings I thought I'd need to use but the crank was in better shape than expected. I'll check those out first and if its too tight, I'll see what my options are. Rumors are floating around about a recently available AMC bearing (Clevite?) that is camfered to help with the clearance.
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