[steve25]

If you run a stick car you can drill through the thrust bearing and into the oil feed passage to get positive oiling to both thrust surfaces.
Drill this at .035"

[taff2]

These are the mods I made to my '59 389 block,they cost me a little time but no money, I saw no reason not to do them considering all the other work I was doing to the block. I plan on putting 1400hp through the block,so - I enlarged and smoothed the oil galleries that go from the oil pump to the filter, and from the filter to the main gallery, IIRC they were increased to 9/16". Oil bypass was blocked. I smoothed off the internal 90 degree sharp bends in the galleries by threading a long thin strip of emery cloth through the galleries and pulling back and forth on it to take off the sharp edges where the factory drill holes meet. I have the normal 0.030" restrictors in the lifter bore oil feeds, but I also restricted oil to the cam bearings, I drilled a 1/16" hole in the cam bearings which I then lined up with the oil holes in the block. I smoothed off the sharp edges where the oil passages meet at the main saddles, and then polished these internally with a piece of emery cloth fitted into a slot in a piece of steel rod chucked in a drill, in an effort to prevent cracks in this area (I also did this to the main galleries). The lifter bores have 0.020" deep grooves cut into them to positively oil the flat tappet cam lobes, I've slotted the main bearing shells to line up with the block holes,and I've put a 0.020" chamfer across the parting line of the thrust bearing shells. And of course I have threaded plugs in the main gallery holes, the one by the distributor gear has the 0.030" hole in it.

[Craig Hendrickson]

A lot of good attention to small details! That sometimes means the difference between a winner and a trailer queen with a broken engine.

[gtofreek]

Originally Posted by grandville455

Are any of you guys doing anything to the main bearings themselves? Opening them up and then chamfering back smooth for more flow to bearing?

One of the most important things to do to the bearings is to remove all the high spots around the numbers stamped on the backside with a fine toothed file, than lightly sand with 1000 grit and Scotchbrite. This will only reduce the thickness of the bearing by .0001" and eliminate any high spots that WILL push the bearing into the crank in spots. If you install a new bearing out of the box, and torque the crank down, turn the crank, and remove it, you will see shiny edges on the bearing, and maybe shiny spots where the letters are stamped into the back of the bearing. The thrust bearing will be the worse, with both outside edges being shiny. This is because on the backside of the thrust bearing, it is not flat all the way across. When you get about 1/8" from the flange, it is raised up about .001". This takes .002" out of your bearing clearance and causes the bearing to rub the crank at the edges. I remove that hump on each side until there is no evidence of the edge of the bearing getting shiny. The chamfer in the main webbing and the thrust cap are not enough to allow that hump to fit into. I have not seen a chamfer wide enough yet to clear those humps. All the other bearings will have a slight raised edge on the backside also. I just lightly file it off so it doesn't rub the crank too. You can't feel the ridge with your fingernail, but it's there and you see it when you hit it with a file.

I do the same thing to the rod bearings. Then I use fine Scotchbrite to put a cross-hatch pattern on the bearing surface and remove that coating they put on. Some of those coatings are very rough and I don't like them. Especially the coating found on the FM stock replacement bearings. The cross-hatch pattern helps to retain an oil film.

[gtofreek]

I also cut a chamfer on the parting lines of the thrust bearings to go from the center oil groove to the rear for positive oiling of the thrust flange.

[GTO]

Originally Posted by johnta1

What did the inside of pan look like when you changed the pump?

Sounds like a bearing possibly going?

What brand of filter?

Pan was clean ass a whistle. My bald head was reflecting off the surface. I was running a Wix Race filter. I usually run a System 1 filter but I was still waiting for an O ring kit so I put on the Wix.

[johnta1]

That's great it was clean.


System One is good and so is the WIX filter.

Hopefully it's some odd-ball thing.
(hose partially collapsing, etc)

[mgarblik]

We do all the mods that Taff2 described in detail. They are all great ideas and have to help. Those simple "blueprint" ideas are good practice for any Pontiac build. Also, GTO, if you PM Eric Larson he can give you the standard o-ring numbers for all the System 1 O-rings. We buy them in quantity, as we have to change them every run. The nitro kills them and makes them giant size after 1 run. They are CHEAP and readily available once you figure out all the sizes. He has all the info.

[Skip Fix]

Sounds like drilling small holes in the cam bearings is about the same as running restrictors in the passage.

[GTO]

Originally Posted by mgarblik

We do all the mods that Taff2 described in detail. They are all great ideas and have to help. Those simple "blueprint" ideas are good practice for any Pontiac build. Also, GTO, if you PM Eric Larson he can give you the standard o-ring numbers for all the System 1 O-rings. We buy them in quantity, as we have to change them every run. The nitro kills them and makes them giant size after 1 run. They are CHEAP and readily available once you figure out all the sizes. He has all the info.

Thanks for the info, but I have them now and a spare set. This should last me for a while. ... Eric.

[taff2]

Ah, bearing shells,that's another story in its self! I don't go to the lengths that Paul does(though I will look into it now that he's mentioned it), I clean up the backside of the bearings with Scotchbrite, but I also don't like the sharp edges at the parting lines of the shells. You can feel this edge when the bearings are torqued in place even though the bearing shell is thinned out towards the edges,so I run a Swiss file over these edges.( We are only talking about maybe a thou or so (0.001")here.

[gtofreek]

Originally Posted by taff2

Ah, bearing shells,that's another story in its self! I don't go to the lengths that Paul does(though I will look into it now that he's mentioned it), I clean up the backside of the bearings with Scotchbrite, but I also don't like the sharp edges at the parting lines of the shells. You can feel this edge when the bearings are torqued in place even though the bearing shell is thinned out towards the edges,so I run a Swiss file over these edges.( We are only talking about maybe a thou or so (0.001")here.

That's a good point I failed to mention. Every bearing shell has this edge you mention.

[grandville455]

Here's some pics of what my engine guy did. I'm using the Blueprinted Melling Pontiac 60 PSI Race Pump 10540 from Precison oil pumps.

[Blued and Painted]

73 400 block, found the intersection where oil turns UP from the filter housing to the left galley to be miss or offset drilled. I cleaned it up with a drill bit from both directions. Still a little jog through there but i CAN sleep at night.

[mgarblik]

Those bearing mods should work fine. The only thing different from what I do is your shop also opened the bearing shell feed for the second passage that feeds straight up to the cam bearings. The cam bearings already have more oil going there than they can possibly use. Depending on your exact application, I would consider restricting the oil to each cam bearing by drilling your own feed hole or using a bearing with an OD feed groove and not line up the feed hole in the bearing. The idea here is to direct more flow to the main bearings. Again, may not be needed except in the most extreme applications.

[grandville455]

Thx, short block is all together now, so nothing I can do about it. What do u consider extreme lol... be shifting 65-6700 I'm guessing.

[455firebird1969]

With all the hole size and drilling discussed in this thread, the topic of hole quality has not been addressed, so I'll throw in something that should be considered when drilling holes in stressed metal. A standard American twist drill is not necessarily a precision tool, and the surface of the wall it produces (while drilling a hole) is rough, with peaks and valleys. The roughness of the hole wall surface imparts stress risers that can lead to cracking. When a precision hole is required, a drilled hole is normally reamed to an accurate and cleaner hole dimension. Reaming thick holes may not be a practical solution, depending on the thickness. After a hole has been drilled and reamed, the final process would be to use a flex hone to enhance the reamed hole wall surface finish, again removing the high spots from the peaks and valley created by the ream process.

The reamer cleans-up the twist drill hole, and the flex hone cleans-up the reamed hole.

A quality hole starts with selecting the correct drill RPM, and feed rate, in addition to appropriate cutting fluid. Reaming requires the same attention. The final hole cleanup with a flex hone will provide a smoother hole wall surface. This process should not be ignored when drilling stressed metal.

When prepping a block for assembly, among the multiple intricate processes the engine builder applies, I suggest using a flex hone in every hole possible. Regardless of whether or not any oil galley (hole) size is enlarged, a flex hone will clean-up the hole, and enhance the quality of the hole, contributing to less potential for stress cracking.

[mgarblik]

That is a very interesting post. I did finish all the 1/2" drillings with a cartridge roll and a special long adapter arbor. But I did not hone them. The smaller passages to the mains I carefully chamfered, but did not hone. Next tear down, I will do this process. Removing fractured metal is a good idea along with providing higher quality oil flow. To answer an earlier question, I would consider extreme, engine rpm in excess of 8500 RPM. and/or horsepower in excess of 1500.

[gtofreek]

Here is a mod I did to a 400. Did it to help get oil to the rear of the passenger side gallery a little sooner, and to balance each side.

[lust4speed]

The oil galleries in yellow are already 1/2" in the stock Pontiac blocks so guess I'm missing their point. I have taken the passages out to 9/16" and smoothed out the bores and corners, but always wondered if it really was necessary.