Scat stroker crank main bearing question xtra clearance bearings?

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I actually was talking to King Bearings yesterday after doing a fair amount of looking around. They're basically out of stock on SBM main bearings until October/November. You can find some of the 'lesser' stock type King bearings but none of the 'race' type....at least not in standard sizes. I could tell from the guy on the phone that the SBM market was not at the cusp of their interest.

This kinda confirms what a 'very famous' Mopar engine builder told me last week when I asked him about the use of SB Chevy rods (2.100" journal) in a SBM. He said it makes sense as the dimensions are very close and 'you hardly have any rod bearing choices anymore' for the SBM.

But more to the point, I think the Scat crank probably uses a radiused journal, so you need to be cognizant of that....regardless of journal clearance you also need to make sure you have the proper clearance at the radius.
 
Oh, and according to Clevite, the MS 540H bearings are not full groove except for #5




H-series performance, bearing for position number 5 is full grooved. Bearing position 1 2 3 4 are grooved upper valves and plain lower halves

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H-series bearings have a medium level of eccentricity, high crush and rod bearings have a hardened steel back and thin overlay. These bearings also have enlarged chamfers for greater crankshaft fillet clearance and are made without flash plating for better seating. These bearings were developed primarily for use in NASCAR type racing but are suitable for all types of competition engines. These bearings must be used with most aftermarket Steel crankshafts requiring the radius chamfered bearings, such as, Eagle, Scat, Cat, Callies, Lunati, Cola and many others brands
 
gregcon said:
Oh, and according to Clevite, the MS 540H bearings are not full groove except for #5




H-series performance, bearing for position number 5 is full grooved. Bearing position 1 2 3 4 are grooved upper valves and plain lower halves

blank.gif

H-series bearings have a medium level of eccentricity, high crush and rod bearings have a hardened steel back and thin overlay. These bearings also have enlarged chamfers for greater crankshaft fillet clearance and are made without flash plating for better seating. These bearings were developed primarily for use in NASCAR type racing but are suitable for all types of competition engines. These bearings must be used with most aftermarket Steel crankshafts requiring the radius chamfered bearings, such as, Eagle, Scat, Cat, Callies, Lunati, Cola and many others brands
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Correct. I wouldn't bat an eye at using half groove over full groove. Not sure why you are so set on full groove.
 
gregcon said:
I actually was talking to King Bearings yesterday after doing a fair amount of looking around. They're basically out of stock on SBM main bearings until October/November. You can find some of the 'lesser' stock type King bearings but none of the 'race' type....at least not in standard sizes. I could tell from the guy on the phone that the SBM market was not at the cusp of their interest.

This kinda confirms what a 'very famous' Mopar engine builder told me last week when I asked him about the use of SB Chevy rods (2.100" journal) in a SBM. He said it makes sense as the dimensions are very close and 'you hardly have any rod bearing choices anymore' for the SBM.

But more to the point, I think the Scat crank probably uses a radiused journal, so you need to be cognizant of that....regardless of journal clearance you also need to make sure you have the proper clearance at the radius.
Click to expand...

I used to get killed for grinding brand new cranks to SBC LJ size. I got tired of looking for bearings.

Lickily, I have one set of stars rod and main bearings out there for the Stroker deal I’ll build one of these years. If not for that, I’d be turning that crank down too.
 
And of course a lot of Chevy guys have abandoned their own rod journal sizes for the Honda 1.89" size....

Assuming the electric car doesn't kill the internal combustion engine by next year, I predict we'll see 1" rod journals soon.
 
gregcon said:
And of course a lot of Chevy guys have abandoned their own rod journal sizes for the Honda 1.89" size....

Assuming the electric car doesn't kill the internal combustion engine by next year, I predict we'll see 1" rod journals soon.
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Yeah, I like the SBC SJ stuff too, but I don’t know about taking a 2.125 throw all the way down to the Honda journal size.

I think it will move the oil feed hole right to the edge of the bearing, and I’m not sure I like that.

I did turn a BBM crank that was BBC journal down to 2.100 and that was close. I got beat up pretty good for that one too, but it was actually very cool because it reduced the big end weight of the rod a ton.

And that was when you could buy Groden aluminum rods, by FAR the best aluminum rod ever made.

That engine was a serious overachiever.
 
I think covid is creating extra demand and less supply of certain things. I just ordered the Ms540hx bearings with extra clearance so I should be good.
 
In particular, I was hoping for the coated version but it looks like I'm gonna buy the non-coated versions then get them coated.
 
Clevite MS963P bearings are full groove, for what it's worth.
 
Clevite bearing make them and speed pro competition does as well, my 340 mains with the extra .001 clearance came from cleveite, and the rods being the Chevy size came from speed pro comp. Just have to search, I don't remember the numbers, I'll try looking tonight when I get home.
 
I know they are still sold, but the point is they are expensive ($120 set) and the selection is very limited. For the SBC, there are probably 5 or 10 times as many options...and cheap.
 
gregcon said:
Oh, and according to Clevite, the MS 540H bearings are not full groove except for #5




H-series performance, bearing for position number 5 is full grooved. Bearing position 1 2 3 4 are grooved upper valves and plain lower halves

blank.gif

H-series bearings have a medium level of eccentricity, high crush and rod bearings have a hardened steel back and thin overlay. These bearings also have enlarged chamfers for greater crankshaft fillet clearance and are made without flash plating for better seating. These bearings were developed primarily for use in NASCAR type racing but are suitable for all types of competition engines. These bearings must be used with most aftermarket Steel crankshafts requiring the radius chamfered bearings, such as, Eagle, Scat, Cat, Callies, Lunati, Cola and many others brands
Click to expand...


I forgot to mention that you can make a fixture to hold the bearing and put a groove in the bottom half. In fact, a ***** stole mine before I could get it back. I’ve never made another one because I don’t do it all the time. I also made the groove a skosh wider (I say skosh because I can’t remember the exact number) and IIRC some bearings had more of a V shape groove than a U shape. So I ground my tool bit to a nice radius and made the groove what I wanted.
 
Someplace I have a fixture I made to hold the two bearing shells, it allows you to cut back the radius and groove the face if you so desire. It surfaces once in a while from the depths of my junk on one of the benches.....
 
gregcon said:
Someplace I have a fixture I made to hold the two bearing shells, it allows you to cut back the radius and groove the face if you so desire. It surfaces once in a while from the depths of my junk on one of the benches.....
Click to expand...


Well you already have one then. Wish I would have grabbed more of my tooling like that before the rat bastard ripped me and many others off.
 
How did he rip you off? As in, broke in to your shop?
 
gregcon said:
How did he rip you off? As in, broke in to your shop?
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He was the dude that owned the shop, who never paid the guy he bought all the equipment from, never paid the electrician who wired the shop, stopped paying the vendors, ordered and paid for the baddest DYNO on the planet, and when it made it to the shop door he refused it and sent it clear the hell back to Florida, the whereabouts of the dyno are unknown but I may be able to trace it if I called the dude who built it.

Yeah, the guy is still the perfect douche nozzle, and liar and a little *****.
 
If you find bearings cheap that you want to run that are .001" loose but half grooved, just buy 2 sets and use the upper shells only. The oil hole on the bottom does no harm and you'll have full flow. I did this back in the '90s on a '71 360, when the engine kit came with half groove bearings (before I could just GO to Summit or use the internet to research), I just ordered another set cheap from the parts store. On the early 360 I had, I had to carefully grind a tang relief in the block for the #5 upper shell to fit. Kind of scary, but I went slow with a cut-off wheel. Since then I have done later 360s and I think 318s and some big blocks with zero grinding. Later I saw that covered in the Direct Connection engine manual that I had the whole time. LOL. So it was the way they did it back in the early days of W2, etc. By the way, that 260 did tons of street duty and hundreds of 1/4 and 1/8mi passes before I went 416 in my Demon. Then I freshened the motor and changed the cam (bigger) with new moly rings, and REUSED the same doubled set of upper mains and even the CL77 rod bearings.
 
I couldn’t find many 318/340 main bearing options which had extra 0.001 clearance bearings and the ones that are offered are half groove. The only ones I found which were in stock are not cheap, so I’m not buying two sets to get full grooves. I’ll live with half groove bearings.
 
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