Scat stroker crank main bearing question xtra clearance bearings?

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cawcislo

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My scat stroker kit came with Mahle/Clevite ms963p main bearings, but when checking clearances they’re too tight. My machine shop confirmed I only have 0.001” clearance. I need bearings with an extra 0.001 clearance. It doesn’t look like they make ms 963p bearings with an extra 0.001 clearance. The Ms963p bearings are full groove main bearings. There are ms540hx Main bearings available which have an extra 0.001 clearance but they are only half groove.

Anyone make a full grove main bearing with xtra 0.001 clearance?
 
I don't know of any, but if you already have the MS 963-P and the shop measured correctly, just have the crankshaft ground .001" to get the correct clearance and allow use of the easy to get standard size bearings.
Since you are looking at P series bearings, I assume you are running a cast crankshaft. If it is forged, make sure they checked the radius for clearance to the P-series bearing.
 
Also, if it's a daily driver type street car that won't see over 6300 rpm or so, you could stay at .001" clearance and run normal grade 10W30 oil and live a long happy life.
I know more clearance frees up drag and wear, but not enough at lower rpms.
 
The motor will see plenty of street use and some drag racing so I’d prefer to have more clearance. I intend on running the engine hard, otherwise why build a 390 stroker? :) The Machine shop also wanted to see at lease 0.002 clearance on the mains. It’s a cast crank. I also wanted to use full grooved main bearings. The mx540hx bearings with more clearance are pricier and I’d have to buy two sets to make one full set of fully grooved bearings. Is it common for new cranks to be cut an extra 0.001?
 
Bobzilla said:
I don't know of any, but if you already have the MS 963-P and the shop measured correctly, just have the crankshaft ground .001" to get the correct clearance and allow use of the easy to get standard size bearings.
Since you are looking at P series bearings, I assume you are running a cast crankshaft. If it is forged, make sure they checked the radius for clearance to the P-series bearing.
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You can’t grind .001 off of a crank.
 
yellow rose said:
You can’t take that little bit off and do it accurately.
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My opinion: If a competent operator, on a machine that isn't junk, can't grind .001 off, I'd look for another shop; at the very least polish it off......it can be done
 
JBurch said:
My opinion: If a competent operator, on a machine that isn't junk, can't grind .001 off, I'd look for another shop; at the very least polish it off......it can be done
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If you’re lucky enough to have a crank grinder that is less than half worn out, and an operation that can work with taking .0005 off a side, and assuming it’s the same machine and the offset is exactly the same...then yes, you can do it.

In the real world, it’s hard to find all that.
 
100_1760.JPG

30 years behind the wheel!
 
yellow rose said:
What if you have to take .001 off of someone else’s work? How do you know he indexed the throws correctly?

I’ve seen enough that if you ground the crank and you wanted to take off .001 I would say go for it. But not from a different machine and operator.
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This all coming from a perfectionist. Lol. Kim
 
cawcislo said:
My scat stroker kit came with Mahle/Clevite ms963p main bearings, but when checking clearances they’re too tight. My machine shop confirmed I only have 0.001” clearance. I need bearings with an extra 0.001 clearance. It doesn’t look like they make ms 963p bearings with an extra 0.001 clearance. The Ms963p bearings are full groove main bearings. There are ms540hx Main bearings available which have an extra 0.001 clearance but they are only half groove.

Anyone make a full grove main bearing with xtra 0.001 clearance?
Click to expand...

Can get them from summit racing-------------
 
mini said:
These are better and full groove. About 30 bucks more for the set but they have the undersized .001
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I think Ms540h-1 are oversized bearings used when you have too much clearance with standard bearings. I need undersize bearings Used when there is not enough clearance with standard bearings which are the Ms-540hx.
 
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Can you just polish (grind) .0005 off? What does polishing usually do to a crank size when we are talking 5 10 thous? I understand cutting is running in a mic, but grinding would just be time under the grit?
 
cawcislo said:
I think Ms540h-1 are oversized bearings used when you have too much clearance with standard bearings. I need undersize bearings Used when there is not enough clearance with standard bearings which are the Ms-540hx.
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Wasn't sure on the part numb. I bought them locally. Needed them with my scat crank as well. Clearances too tight with std bearings
 
Check out King bearings. I had one bearing bore on my 340 that was 0.001 tight. Too much work to clean up after honing that one bore. King had bearing that had .001 extra clearance. I had to buy a whole set for that one bearing pair. I am assuming you have 360, but if you have a 340 size main I would give you a pair. That worked good for my engine. Kingbearings.com
 
3406pk said:
Check out King bearings. I had one bearing bore on my 340 that was 0.001 tight. Too much work to clean up after honing that one bore. King had bearing that had .001 extra clearance. I had to buy a whole set for that one bearing pair. I am assuming you have 360, but if you have a 340 size main I would give you a pair. That worked good for my engine. Kingbearings.com
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Thanks. I’m working on a 390 stroker (318 based) but all my mains are too tight and I need to get extra clearance bearings.
 
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