full or half groove main bearings

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Rapid Robert

Rapid Robert

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circle track mild 360. 6K at the end of the straights. clearances slightly loose. which should I go with? thank you for your time. RR
 
Full groove Clevite if you can find them, if not half groove will suffice. 65'
 
I agree. I like full groove, too. As mentioned. IF you can find them. Too bad the main journal diameter ain't the same as Chevys. You'd have your pick from several part numbers.
 
I've found very little selection for full groove bearings.

King makes a very nice looking set....they offer them in coated versions, too. The only problem is.....you can't actually buy them. I had a set on order for 6 months...the carrot they dangled continued to move out 3 weeks every 3 weeks. I finally cancelled them. That was after I took the time to call King and get through to their tech line, and the guy there said they were 'in the works' but also sounded like their level of urgency in producing these was a 1, with 100 being the best.

I have some Clevites that are full groove, but they are not the .001" looser race type, and I think there was one other thing about them that made them not as desirable.
 
I wish I could find some for a slant six. lol
 
when I raced I found the fully grooved bearing would cause a oil leak at the rear main getting the clutch wet , by accident we got the wrong set with no time to change after installing the 1/2 grooved ones this stopped the oil leak just a reminder you should drill a small hole in the thrust surface of the bearing so if your hit and the clutch linkage binds it wont wipe out your crank thrust surface (ask me how I know)
 
Another option is cross drilling the crank.
 
gregcon said:
I've found very little selection for full groove bearings.

King makes a very nice looking set....they offer them in coated versions, too. The only problem is.....you can't actually buy them. I had a set on order for 6 months...the carrot they dangled continued to move out 3 weeks every 3 weeks. I finally cancelled them. That was after I took the time to call King and get through to their tech line, and the guy there said they were 'in the works' but also sounded like their level of urgency in producing these was a 1, with 100 being the best.

I have some Clevites that are full groove, but they are not the .001" looser race type, and I think there was one other thing about them that made them not as desirable.
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I used to have a fixture I could slap the bearing in, shove it in the lathe and grove the other half. Of course, when the Iowa prick fired me I lost all that stuff and I doubt the Mexicans who ended up with all the equipment had a clues as to what 85% of the staff was.

You can make one. I need to make another one. It seems like full groove bearings are on the way out.
 
Yeah. I ordered metal to make a fixture but never got around to it. The metal is just sitting there, gathering dust. I was hoping King would come through, but that doesn't look like it will happen. I do have a nice set of Clevite/Mahle bearings that are otherwise good (big radius journal and .001 loose) so maybe I'll groove them and get them coated.

The Mahle bearings mentioned above....I found one seller (1) one Ebay who listed many sets. I ordered them, they arrived, and I went to order more and they were gone. I asked WTF and they told me they actually only had the one set I bought. That was in July, and I've never seen another set being sold by anyone on Earth.
 
Rapid Robert said:
circle track mild 360. 6K at the end of the straights. clearances slightly loose. which should I go with? thank you for your time. RR
Click to expand...
Full groove.
Mains clearance about .002 -.0021, make no.1 tightest but no tighter than .0017, rods at around .002 or so.
If you go with half or 3/4 loosen the mains a hair more. Jmo.
 
teringer said:
when I raced I found the fully grooved bearing would cause a oil leak at the rear main getting the clutch wet , by accident we got the wrong set with no time to change after installing the 1/2 grooved ones this stopped the oil leak just a reminder you should drill a small hole in the thrust surface of the bearing so if your hit and the clutch linkage binds it wont wipe out your crank thrust surface (ask me how I know)
Click to expand...
I have a tendency to believe you though there is that little chance the seal just leaked and when you put the new ones in the new seal.. didn't. but in consideration of that I wonder if just swapping out that we are bearing and leaving the rest would be the fix.
 
yellow rose said:
I used to have a fixture I could slap the bearing in, shove it in the lathe and grove the other half. Of course, when the Iowa prick fired me I lost all that stuff and I doubt the Mexicans who ended up with all the equipment had a clues as to what 85% of the staff was.

You can make one. I need to make another one. It seems like full groove bearings are on the way out.
Click to expand...

Cheap and easy. Hack the bearing saddle and main cap out of a worn out/broken engine block. Square it up in the mill. Drop it into the four jaw with the bearing mounted and cut your groove. Only downside is checking concentricity after each bearing. with a little extra work you could braze a stub shaft contraption on so it would be set up once for each session. Probably could do the same thing with the big end of a connecting rod too. If you have the material to start from scratch, all the better. I don't think you'd have to dial in to the fourth decimal place. The groove depth varying a thou or two shouldn't kill anything.
 
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Just a comment...I was talking to Dan Dvorak Friday on the phone. He's the well known Max Wedge racer...also does a lot of various Mopar engines for others. He commented the small block is the hardest engine to avoid rear main seal leaks, and that too-high oil pressure is the #1 cause. He also said what I kinda already do...install the seal without any sealer or silicone, and do not stagger the seals. He said he looks at each seal and rejects the ones that don't fit in the cap/block slightly taller than the parting line.
 
The rear main seal leak in SBM's is more prone to happen when the high pressure oil pump is used versus the high volume pump. Or someone changing out the spring to increase pressure.
 
gregcon said:
Just a comment...I was talking to Dan Dvorak Friday on the phone. He's the well known Max Wedge racer...also does a lot of various Mopar engines for others. He commented the small block is the hardest engine to avoid rear main seal leaks, and that too-high oil pressure is the #1 cause. He also said what I kinda already do...install the seal without any sealer or silicone, and do not stagger the seals. He said he looks at each seal and rejects the ones that don't fit in the cap/block slightly taller than the parting line.
Click to expand...


Amen to that. Sometimes you have to trim the ends of the seals down because they are too proud. When you torque the cap down, the seal is forced out of round and it leaks like a sieve.
 
Demonracer said:
The rear main seal leak in SBM's is more prone to happen when the high pressure oil pump is used versus the high volume pump. Or someone changing out the spring to increase pressure.
Click to expand...


I’ve run over 100 psi at 8500 RPM and if the seal is correct it won’t leak. Even used a rope seal and it didn’t leak.
 
On my engine, I'd use a rope seal but the Molnar crank has a smooth journal, no cut lines. So I think the rubber seal is a better bet.
 
I made up the bearing jig today. Like a lot of things, if I made another one, now I'd know just how to make it better.

Anyway, I made it so it can hold any of the three different main bearing shells...though in my Mahle set, the #5 is already fully grooved, so I just need to cut the upper halves of 1-4. I decided to order a new grooving tool so I gotta wait for that to arrive before I actually do it.

I used my new bore gage for the first time....it made getting the bore diameter very easy and accurate. This gage is really more of a comparator than a gage....it's very useful at comparing two pieces. It measures in .0001" increments and I wound up leaving the jig .0002" tighter than the engine's saddle. Close enough.
bearing holder.jpg
 
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