[68hotbird]

My first set of king main bearings should I do the oil hole modification like I do on the speed pro bearings with the oil slot or just leave the single round hole. Will be a 6800 rpm drag motor.

[GTOGEORGE]

Originally Posted by 68hotbird

My first set of king main bearings should I do the oil hole modification like I do on the speed pro bearings with the oil slot or just leave the single round hole. Will be a 6800 rpm drag motor.

I did........er I did my own mods to the holes.


GTO George

[Dragncar]

Yes, I take a Sharppie and mark the hole in the block on the tab side and transfer. Start with a 1/8" drill and work my way up. Then take a jewelers file and debur. Thats how I do it anyway.
Oil slot is OK but just having one round hole is a no go for me.

[steve25]

If your dealing with a factory block look carefully at how the oil holes are drilled in the main Webb's .
You will then see that the factory drilling on the holes form a V shape that feeds the oil flow from the feed passage to the Bearing holes and the Cam Bearings.
Theses drilled V openings are where the flow restriction is when you look at things area wise and not the oil holes in most main Bearings.

[taff2]

I cleaned up the 'V' openings with a die grinder so there is more of an oblong slot there now, radiused of course to remove the sharp edges.

[Jack Ferris]

Does anyone have any pics of this mod?

[77 TRASHCAN]

Who is the best (or any) for King bearings?

[Dragncar]

Originally Posted by Jack Ferris

Does anyone have any pics of this mod?

The oil hole in the block with the blue dye around it is the hole that gets the oil shot. This is a FM bearing with the oil slot that has been modified to get the full shot of oil with nothing in the way.

[Dragncar]

This is a Clevite main bearing with just a round hole like a King. Never had a King bearing though, but I see no reason you could not do the same thing with a King as I did with the Clevite.
This right here, this modification is one of the reasons I have never hurt a engine, spun a main or spun a rod bearing.
Its a old Dan Whitmore trick. He told me if I did not do this with my original Vanderville bearings i would starve the rods of oil at high RPM. I listened, it works.

[mgarblik]

Originally Posted by Dragncar

The oil hole in the block with the blue dye around it is the hole that gets the oil shot. This is a FM bearing with the oil slot that has been modified to get the full shot of oil with nothing in the way.

This is essentially what we have been doing with main bearings in any serious race application. Have had good success in 15+ years doing this pretty simple mod. For those who haven't studied Pontiac oiling circuit, keep this in mind. The angled hole from the main bearing saddle is providing the essential oiling to the mains and the rods through the crankshaft. The center hole is a riffle drilling to the cam bearings. It is way too large for serious performance use and was likely drilled at this huge 5/16" size to reduce drill bit walk and tool breakage in rapid production. The cam bearings reduce the effective size some, thank goodness. The oil feed slot in a FM bearing does at least expose some of the angular hole to direct crankshaft oiling. The bearing mods simply expose more.

[Jack Ferris]

Great info. Thanks. What about the mods to the oiling holes?