S & S lifter cuff compatibility
Thread Starter
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Seasoned HDF Member
Joined: Jan 2009
Posts: 12,697
Likes: 8,304
From: Ottawa, Ontario
Originally Posted by MotoJockey
OK, just because this is the first M8 that I've kept, (got rid of two 17 RKS for tranny fluid transfer), I'm just now getting into this M8 motor, per se. I looked up some lifter cuffs to see what we're talking about here, and have a question. If the cuff doesn't touch the lifters themselves to like help guide them or something, what is their exact purpose? To keep the lifters from flying out of their assigned lifter bore? Just curious...........
I'm not saying it's common, in fact it's probably pretty rare, but why do you think S&S developed and sells a metal cuff? And why do people here recommend it?
So for someone to say because they have never personally seen or heard of it happening means it doesn't exist....
Google is your friend. Personally I intend to install the metal cuffs, they are cheap insurance. The reason I started this thread was because someone had posted something about Fueling supposedly not recommending the use of metal cuffs with Fueling lifters and I wondered why Fueling specifically.
I could not find any mention of that anywhere. As someone already answered, it probably pertained to using Fueling oversize lifters with the metal cuffs as mentioned previously in this thread. Or maybe they didn't use a shim to make sure there was no contact with the walls.
Grand HDF Member
Joined: Jun 2017
Posts: 4,686
Likes: 3,984
From: Near Yosemite
Got it fellers........ "Anti-Rotation" device! I should've figured that out, but having never taken an M8 apart YET, that slipped past me. Of course, I'm aware of the anti rotation pin in the TC's, but I guess the MoCo had a better idea and now I know!! Thanks gentlemen! 
OK, here we go, lol. As mentioned, it's to prevent the lifter from rotating in the bore which results in the roller no longer being aligned with the cam lobe. I've seen numerous photos of M8 lifters where the lifter roller has had a flat spot ground down because it's rotated in the bore with the plastic cuffs, plus photos from the top of the roller actually sitting cockeyed in the cuff.
I'm not saying it's common, in fact it's probably pretty rare, but why do you think S&S developed and sells a metal cuff? And why do people here recommend it?
So for someone to say because they have never personally seen or heard of it happening means it doesn't exist....
Google is your friend. Personally I intend to install the metal cuffs, they are cheap insurance. The reason I started this thread was because someone had posted something about Fueling supposedly not recommending the use of metal cuffs with Fueling lifters and I wondered why Fueling specifically.
I could not find any mention of that anywhere. As someone already answered, it probably pertained to using Fueling oversize lifters with the metal cuffs as mentioned previously in this thread. Or maybe they didn't use a shim to make sure there was no contact with the walls.
I'm not saying it's common, in fact it's probably pretty rare, but why do you think S&S developed and sells a metal cuff? And why do people here recommend it?
So for someone to say because they have never personally seen or heard of it happening means it doesn't exist....
Google is your friend. Personally I intend to install the metal cuffs, they are cheap insurance. The reason I started this thread was because someone had posted something about Fueling supposedly not recommending the use of metal cuffs with Fueling lifters and I wondered why Fueling specifically.
I could not find any mention of that anywhere. As someone already answered, it probably pertained to using Fueling oversize lifters with the metal cuffs as mentioned previously in this thread. Or maybe they didn't use a shim to make sure there was no contact with the walls.
I did Google the plastic cuffs in Chevrolets, the Corvette forum did make some mention of them failing at times. It didn't seem to be a common issue with them either.
Got it fellers........ "Anti-Rotation" device! I should've figured that out, but having never taken an M8 apart YET, that slipped past me. Of course, I'm aware of the anti rotation pin in the TC's, but I guess the MoCo had a better idea and now I know!! Thanks gentlemen!
Stellar HDF Member
Joined: Sep 2007
Posts: 2,468
Likes: 678
From: Vancouver Island B.C.
Something else to sell, also for people with higher lift cams.
Because they have them? Kinda like cam recommendations and you ask why "that one". Because it's the one I have.
Because they have them? Kinda like cam recommendations and you ask why "that one". Because it's the one I have.
Thread Starter
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Seasoned HDF Member
Joined: Jan 2009
Posts: 12,697
Likes: 8,304
From: Ottawa, Ontario
Harley does things at times that I find baffling. The pin to me seems to be a really good solution to the rotation of the lifters, yet it was abandoned in the M8 and the plastic cuffs were implemented. I am sure when they are designing a new engine there are cost considerations, maybe the cuffs are significantly less expensive. Also, since there are 17 years between the TwinCam release and the M8, I am sure many of the developers of the TwinCam probably weren't still around when the M8 was being conceived. All in all though, the M8 has turned out to be good engine that is easy to enlarge if that is your desire. Roussfam, best of luck with your build.
HD EFI Guru
Joined: Jan 2008
Posts: 4,496
Likes: 4,787
If your going to worry about the lifter cuffs then modifying the engine should not be done. The S&S or any other copy of them, just does nothing better than the stock ones, unless your going to be putting a very high lift camshaft and at that point your going to be doing much more in the engine. If you have money to burn then go for it but your not gaining anything. The same thing applies for the aftermarket oil pumps and cam plates in the M8's. The OEM 2020 and later oil pump is more than acquit as is the OEM cam plate.
Stellar HDF Member
Joined: Aug 2020
Posts: 3,192
Likes: 2,235
From: College Station, TX
I've heard many stories about the bolt that holds the lifter cuff breaking off when replacing the cuffs, but nothing about them failing. No doubt they will eventually fail, but it does not appear to be a common problem.
When the bolt breaks, it becomes a big deal to get it out. So if you decide to replace the cuffs, approach that with caution and perhaps a little heat.
Paul
When the bolt breaks, it becomes a big deal to get it out. So if you decide to replace the cuffs, approach that with caution and perhaps a little heat.
Paul
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From: poway
Club Member
Joined: Apr 2016
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From: Inland NW
I have not seen any reports of failures related to someone installing the S&S cuffs without the required clearance (use of feeler gauge when torquing fastener)
Has anyone seen or heard anything about binding related to this?
Has anyone seen or heard anything about binding related to this?