Enlarging FE Main Bearing Oil Holes

blykins · #1 (**permalink**) 07-13-2005, 07:51 AM

Guys...

Reading Steve Christ's book, he has a standard on if the main bearing oil holes need to be enlarged or not...and gives the spec on how much should be showing.

He doesn't, however, tell how far to drill through....

Are you supposed to drill the hole out for the length of the oil hole itself....? Or are you just supposed to enlarge and chamfer the opening?

57fairlane428 · #2 (**permalink**) 07-14-2005, 02:56 AM

They don't line up completely. I would also like to know if this is a problem. Mine are all at about 50% blocked with the bearing halves inserted but still plenty large enough for oiling.

chuckbrandt · #3 (**permalink**) 07-14-2005, 03:10 AM

The guys at Gessford did my block and they did a little work to align the main bearing oil holes with the insert. Here is what it looks like.

Chuck

blykins · #4 (**permalink**) 07-14-2005, 05:20 AM

Ah.....so they didn't actually drill the hole out....they just moved the opening so to speak....hmmm....

chuckbrandt · #5 (**permalink**) 07-14-2005, 05:30 AM

Just to align the hole with the holes in the bearing inserts. Obviously they will still run without this proceedure but it seems like a good idea none the less.

Chuck

57fairlane428 · #6 (**permalink**) 07-14-2005, 03:23 PM

did you align bore the mains after you fixed the oil holes? Looks like a fresh set of mains.

chuckbrandt · #7 (**permalink**) 07-14-2005, 03:27 PM

Yes they did decide to align bore the mains, although I'm not sure the reason.

Chuck

blykins · #8 (**permalink**) 07-14-2005, 04:23 PM

I'd say they did it to get rid of any burrs or inconsistencies where the oil passages were clearanced....just as a precaution so that the bearings would sit nice and flush.

Excaliber · #9 (**permalink**) 07-14-2005, 04:27 PM

What they did is commonly referred to as "chamfering". It's done to most if not all of the oil holes in the block. Especially where the oil filter adaptor bolts to the block, extensive chamfering required there.

Chamfer and de-bur are often done together. De-bur is simply removing any rough or sharp edges that under stress may be the starting point for a crack.

Align bore? Gessford leaves NOTHING to chance!

Heres a pic of my chamfered and de-burred block. Note how LONG the chamfer is for the oil filter adapator.

blykins · #10 (**permalink**) 07-19-2005, 05:13 PM

Guys...what would be the best tool to use for this? Die grinder? Step bit?

Keithc8 · #11 (**permalink**) 07-19-2005, 11:26 PM

These are all common procedure mon any FE engine build. You can place your bearing in the saddle and mark the hole in the bearing. Use a die grinder to chamfer the oil galley over to the bearing hole location you have marked and then deburr the area you ground. As stated above it is a good ideal to do the oil filter mounting pad area as shown as well as where the oil pump mounts. It is also a good ideal to open the passage from the oil pump to the filter mount if not 7/16. We drill all of the early blocks main oil passages to 7/16 since some of them were smaller than this. Good luck, Keith Craft

blykins · #12 (**permalink**) 07-20-2005, 04:55 AM

Thanks Keith. May the die grinding gods be with me.

Rory428 · #13 (**permalink**) 07-20-2005, 09:39 AM

Although a mild chamfer job to line up the oil holes to the main bearings is OK, enlarging the entire passage between the cam & crank bearings is a bad idea. The most recent 428 in my Fairmont drag car split the block bulkheads between the cam & crank in the #2&4 positions, from the center of the main bearing oil hole, right down to the cam bearings. I didn`t realize that I had a problem until the oil pressure started getting lower & lower, eventually dropping down to almost nothing at idle. When I pulled it apart, the 6 year old main & rod bearings still looked great, but the cracks were bad enough to allow the cam bearings at #2&4 to walk out of position, which caused a masive internal oil leak. There is not very much metal around the main bearing feed gallerys, drilling these holes larger would just weaken the block, in my opinion.

blykins · #14 (**permalink**) 07-20-2005, 10:00 AM

That's what I was thinking too.....Keith has said that the blocks were weak in this area.

Also, a cam bore align hone would be necessary to take care of any burrs that you couldn't get to....that's a rough spot to be grinding in.

Excaliber · #15 (**permalink**) 07-20-2005, 10:44 AM

That was the "main" reason the side oiler came out. It corrected the inherit weakness of the center oiler block prone to cracking in that area.

mickmate · #16 (**permalink**) 07-20-2005, 10:59 AM

I have a copy of an article on FE lubrication mods. They recommended drilling the oil gallery from the pump to the filter housing (shown in the picture) I think from 5/16" to 3/8". I believe that was the only one they recommended making bigger, some were made smaller like adding a socket screw with a hole drilled in it for the hole from the valley that feeds the distributor gear. I'll try and dig up the article for you it had a few good tips. Mostly just aligning and deburring stuff like you're doing. The bearing holes you are aligning I think the book recommends drill bit sizes to check alignment and opening. I would say you're on track opening them to the hole (and whole) opening of the bearing.

blykins · #17 (**permalink**) 07-20-2005, 11:39 AM

I'd appreciate it if you could find the article for me. I'd like to get all of this right the first time around.

I've read the same thing you've read on using a drill bit to check the opening. I think it's in Steve Christ's book where I read that....

mickmate · #18 (**permalink**) 07-20-2005, 08:42 PM

Hi Brent, I found a couple of articles from Nov 01 Mustang Illustrated an article by Roush on modifying the 390 and also an FE buildup over several issues of Street Rodder. The June 01 issue has the goods on oiling. Send me an e-mail address and I'll try scanning you a couple of pages. It's a pretty standard mod according to them to run a 1/2" drill (not 3/8" like I said earlier) through from the filter side to the oil pump stopping just short of the end of the passage. Then you take a die grinder and port match the oil passage to the oil pump. Go slowly and easy on this with no lube as you don't want to snap a drill. The cast iron is the good stuff on these and drills quite well. I did it to mine and was very pleased with the results.

blykins · #19 (**permalink**) 07-21-2005, 05:08 AM

You have a PM waiting for you.

Thanks a lot....that's a big help.

mickmate · #20 (**permalink**) 07-21-2005, 09:28 PM

Hey Brent let me know if they all work. The other one I was talking about was the galley plug behind the distributor. I guess most people either leave it in and don't clean that galley or remove it and clean it out but leave the galley oozing precious engine blood. SR recommends a plug with an 0.030" hole drilled in it to really help out dizzy gears and cam lubing without losing system effectiveness. I can get a couple of digital pics of mine if that will help. Stay on it and let us know how it works.



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