WARNING about King Main Thrust Bearings

I wanted to share an important "heads up" regarding King main thrust bearings that have been produced since 2024. Engine Tech branded 7.3 IDI main bearings are in fact King bearings just repackaged by Engine Tech FYI. I received a set of Engine Tech Mains from my machine shop a year ago and recently started the actual assembly process. While doing so I discovered the the thrust mains in the kit slipped onto the main cap and block side groove VERY easily. Too easy. I tried these same bearings on another 7.3 in shop and same thing. The thrust main that was removed originally also happened to be a King bearing and it required significant force to remove this bearing from the cap and block side.

My concern here is if the bearing is not an interference fit, I risk "spinning" the thrust main bearing. Note, all other mains fit tightly. I purchased an NOS Ford OEM bearing on ebay for super cheap to take measurements off of to compare. I also purchased a second set of King Mains from rockauto from a more recent production run (2025) to compare. I've tabled my findings below.

I called King's tech line and the guy who answered was very knowledgeable and helpful. He helped me confirm the bearing should not be falling out and confirm the specs that would cause the bearing to not fit tightly. The "free spread" spec is the issue here. Ultimately, he let me know the 2024 main I have from them is out of spec and, personally, he would not use them and send to send them back where I got them. I have not told him about the 2025 main also being bad but I think I will as something isn't right in their manufacturing process. Next Prod is estimated to be January 2027 and likely to be bad if no one raises their hand..

Please note, these findings may not be reflective of every single one as my sample size is small. But does not look good when two diff production runs are similar.. Also note this may not even be a problem in practice as I am sure many have used King mains since 2024 w/o consequences. I am just particular and have spent a great deal of $ on this build and do not want to risk a spun bearing. Luckily I located an NOS set of Mahle/Clevite MS1596P10 mains and have ordered them. I can measure these and report back if anyone is interested.

This is an example of why I prefer to use Clevite bearings only.

@IDIBRONCO I thought I read somewhere that clevite discontinued Main Bearings for the idi. Do you know if that's true?

I have no idea on that one. I haven't bought any IDI main or rod bearings since 2018.

I'm in the process of freshening my '94 IDI engine. Just last week I ordered and received a set of standard Mahle/Clevite main bearings, part no. MS-1596P from Rock Auto. But I bought Enginetech connecting rod bearings. Now you got me wondering. I have to definitely mic every bearing and its fit up now for piece of mind.

Good info to know. Thx for sharing.

Sparks-IDI said:

I'm in the process of freshening my '94 IDI engine. Just last week I ordered and received a set of standard Mahle/Clevite main bearings, part no. MS-1596P from Rock Auto. But I bought Enginetech connecting rod bearings. Now you got me wondering. I have to definitely mic every bearing and its fit up now for piece of mind.

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I would be curious what your free spread and saddle width measure. I just used a quality set of calipers. For the rod bearings, as long as they are pushed into the rods and cap tightly and are not falling out on their own, you should be fine. Make sure you plasti gauge to check your clearance and if all that comes out okay you're good to go.

I happen to be working on the engine today. So I got the measurements you and I both were wondering about. Looks like these pass the test. I've got a dial bore gauge so I am definitely going to test fit all bearing fit ups. Appreciate the effort in this. My old bearings actually look just fine. Could of just left them alone, but figured since I'm in there, just give the crank a quick polish, replace the bearings and go.

Thanks for sharing those. You're golden. Gives me reassurance my NOS set coming will probably be ok.

Got my nos Clevite thrust bearings in today. They measure 3.322-3.323" so in spec! I plan to run these.