main bearing gallery modification

[centredautomag]

I installed race main bearing yesterday with block modification I want to know if I am good to go or  do I have to enlarge the gallery a bit more  thanks

[blykins]

It all depends with how it lines up with the hole in the block.  I usually just blend over the end of the hole in the main saddle.  Never had any issues doing it that way. 

Make sure and walk your bore mic over to the other side of the bearing when you check your clearances. 

[centredautomag]

Thank you Brent  I did blend the hole  do you think I should  blend some more .

[blykins]

Some guys here shape the hole in the bearing.  I don't see anything wrong with that.  Some guys shape the hole in the block and leave the bearing alone.  I don't see anything wrong with that either, and that's how I do it.  All that matters is that the holes between the bearings and the holes in the block match up better. 

If you can lay your bearing down in the block and the holes line up, then call it done. 

[centredautomag]

OK will do. thanks.

[My427stang]

I would live with those

Here is one that needed work for comparison



I don't' have a pic, but I just laid a small burr in there and opened up the galley toward the groove

BTW, that was a running 428 with a perfect standard crank and bearings, so they don't need a ton of area, but too close for me

[Rory428]

I have to say, that I have never had a main bearing hole that badly out of alignment, that said, if that block was used in an engine that was first built 50 years ago, I guess an adequate amount of oil must have gotten to where it was needed. For many years, I used to always take a die grinder and blend the oil holes to make them line up perfectly to the hole in the bearing shells. I stopped doing that over 10 years ago, after one of the 428 blocks in my Fairmont drag car split the main webbing on the 2nd & 4th bulkheads between the cam and crankshaft bores. The cracks went directly through the oil feed holes, right where I had chambered the holes.  Now, maybe the cracks would have happened even if I never had touched the holes with a grinder, I don`t know. I did not really remove very much material, but it cracked right there. I remember years ago, hearing about guys that actually drilled the oil holes in the main webs larger than stock. Considering how narrow the web bulkheads are, that sure sounds like a bad plan.

[centredautomag]

It is exactly like mine look before I blend the opening in the block. Did not look that bad with stock
Bearing ( round hole).

[Ranch]

Looks like #1 Main, lucky cause that’s the one with most pressure but that is still not much room.  The bearing shells with a hole in in the lower half usually give you more area for oil to get by.  I think you should pay more attention to 3, 4, & 5 since you are moving farther from the pump, still Ross’s pic I would definitely match the hole better….JMO

[wsu0702]

You should always modify the bearing and leave the block alone IMHO.  The edge of that hole is where the main saddle to cam tunnel cracks always initiate on high output FE engines.  Not as much of an issue on a cross-bolted block but even then I would not recommend removing material around the edges of this hole. JMHO   

[blykins]

That's a standard area for factory blocks to crack and I don't think it has anything to do with chamfering or laying over the end of that hole.  Factory FE blocks are notorious for splitting between the cam journals and the mains. 

I don't see anything wrong with blending the block or blending the bearing either one.  It's a discretionary thing.  On a Pond block instruction sheet, you will find instructions to blend that hole to match the bearings and the new BBM blocks have a step there, machined into the block to make bearing alignment better. 

[cjshaker]

Years ago, Shoe found papers from Ford explaining why the hole was drilled off-center. If I recall correctly, it was to intersect the cam hole in the proper location. I think it even addressed the issue of being off center to the crank bearing, saying that blending wasn't necessary. Just my opinion, but if tolerances stack up in the wrong direction, it may still be beneficial. I would think, using some common sense while doing it, not to go too far, that a slight carefulchamfer there might actually help stop the crack from forming in the first place, since sharp edges promote crack formation. I'm sure Rory would be the first one to admit that years of dumping the clutch at 5000+rpm probably didn't help his situation 

[RJP]

Years ago, Shoe found papers from Ford explaining why the hole was drilled off-center. If I recall correctly, it was to intersect the cam hole in the proper location. I think it even addressed the issue of being off center to the crank bearing, saying that blending wasn't necessary. Just my opinion, but if tolerances stack up in the wrong direction, it may still be beneficial. I would think, using some common sense while doing it, not to go too far, that a slight carefulchamfer there might actually help stop the crack from forming in the first place, since sharp edges promote crack formation. I'm sure Rory would be the first one to admit that years of dumping the clutch at 5000+rpm probably didn't help his situation 

My understanding of the offset oil holes at the mains was to force more oil to the lifters in passenger car engines. If you look at truck/industrial/marine blocks the oil holes line up, I assume all 427 blocks as well. [At least the 3 of mine do] In the past I've copied the way truck/indust./marine/427 blocks are machined by aligning the oil holes. If Ford did it that way then there must have been a good reason for it.

[Ranch]

My '62' 406 never matched.
This shop notice has been around awhile, when you look at the check hole Diameters you notice how the they get larger going away from the pump

[My427stang]

If it bothers you, you can also use a different style bearing.

I know we tend to like the FM 3/4 bearings, but lots of them have a bigger feed hole. 

Pic from the old forum, no idea on brand