Main bearing install tip.
 

When you install the bearings on the oil feed side of the case you should bevel the back of the bearing with a drill bit.Just think of Rawknees Turbo with an impish grin as he is about to drill it Texass style.Just kidding as it aids in the entry of the oil.In the picture the last two on the right are not beveled.I have been doing this since 1975.Good luck with your build.Fredhttp://forums.pelicanparts.com/uploa...1497557742.jpg
http://forums.pelicanparts.com/uploa...1497557800.jpg

FaaptabulousFred, I had you pegged (:eek:) as someone who would gnaw the bevels wiff his toof!

I love these tip threads from guys who were in the trenches back in the day.

So is the hole in the case same size as bearing hole? Or is it larger thus the gradual transition?

One tip I recall from a guy whose only job was competition engine building: He used feeler gauges between rod and crank (sides) when torqueing rods to crank to limit any distortion to bearing from twist. Many assembly tricks go into the best builds.

hole size
 

The exit hole in the bearing saddle is larger than the bevel.I am assembling a 77 Carrera 3.0.I will take a pic tomorrow of both.

I have just acquired a 77 3.0 in pieces.. would love to see more photos of your build...

A much better way to do this would be with a die grinder and carbide bur with small or fine grinding flutes.
A drill bit will never make a smooth cut and this whole thing is a risky idea.
I trust the way Porsche designed this... they just might know what their doing.

Agreed. Shade tree stuff at best. This is not the way to do this.

This should be done with absolute care. With a drill bit is absolutely wrong. A proper chamfering tool bit would be the proper way and the right angle bit as well. Care should be taken with either so you don't dimple the inner side of the shell and take away any clearance. Doesn't take much to lose 0.001" clearance on the shell.

Doubting Thomases........
 

I don't know how many engines you guys ever built. Both of you could combine your total engine rebuilds under your belts and double them, the total combined number would probably not be even come closer to what Fred built. And he has retired but is still rebuilding motors better and quicker than anyone I know.

A couple of years ago before I met him, I refused to believe that anyone could have done so many engine rebuilds and probably over exgerated the numbers. Unfortunately, I was wrong. He had a successful Porsche work background that we could only dreamed about. I wished I have known him much earlier and benefited more from his experience. I am delivering my 14th engine rebuild this weekend for a fellow PP member. And Fred has done more than a hundred times more and I could only say, wow!!!! Yes. A hundred times more and a lot more.

Tony

I had the opportunity to watch a famous engine builder assemble a high performance small block chevy and every sharp edge was chamfered, rod and main cap mating edges, oil passages in crank and block, oil holes in bearings, ends of all shell bearing. What also surprised me was the pistons. rings and cylinders were assembled dry. Engine screeched for a minute when started. He claimed this was the most effective way to achieve the best ring seating

And that is in addition to spending much of his free time leering at Costa Rican hotties - in the flesh (the lucky bastage)!!! :D

"Ignorance is bliss" and don't complicate the matter with facts, ...right???

getting drilled
 

It is a simple process really.Slow speed with a sharp bit.Each bearing takes 3-4 seconds and it is done.A quick spin at the end barely touching it and the finish is clean.Here is a pic of the case with the bevel.The next pic is a picture of a factory replacement case from 78 with a larger bevel in the case.It is about 3mm deep.http://forums.pelicanparts.com/uploa...1497729533.jpg
http://forums.pelicanparts.com/uploa...1497729533.jpg
I am working on a third Carrera 3.0 engine and will have it apart tomorrow and will check it out.Maybe in the future I will hire a retired bored Dentist to handle this task in a manner that suits all.Maybe anality could be a profession after all.Anyone need a part time job?More shadetree tips in the future.Fred

I did this once, and yes, it blew my motor up. We found that when I countersunk the hole using a drill bit, I distorted the bearing shell by 0.0002" while pressing down on the drill. This caused a high spot that prevented oil to fill the space between the journal and the bearing shell.

Well, it wiped the bearing and threw a rod.

Just kidding. No, this never happened, nor will. Unless you are super careless. :rolleyes:

Some of you guys think you're building a rocket for space..... :D

I have seen this. Also a slight spritz of WD40 like product to limit surface rust but nothing else.

I do think Porsche did a good job with producing street engines in a timely manner to make a profit. But race engines with higher redlines probabaly benefited from a lot these types of tips.

This bevel trick might not make a difference in a normal street build but I doubt it's harmful if performed in the manner Fred has shown.

I find nothing wrong with the idea of this, just the way its done. Its important that anything given as a tip is thought out carefully. This forum is for the DIY owner who may not understand or know the importance of making sure no machine marks are left after doing this mod.

Doing this with a drill bit can leave these machining imperfections that can lead to oil distribution issues and possible bearing starvation.

shade tree
 

I was a shop foreman at Herman & Miller in 1975 with 13 mechanics under my watch.Joe Heman had just bought #36 White 934. They made me crew chief.A few weeks later a couple of German mechanics show up from Porsche Racing with 2 wounded 935 motors .The one guy is Dieter and the other guy is Alwin.They use our engine room and when the new bearing pacs are opened up they drill the back of the bearings like I have done since 1975.Cool thing is a year later in 1976 they opened Andial in California.I am proud to be a shade tree mechanic.I spent today with Peter Dawe helping him in his shop.He worked many years for Andial.No ONE better on the East Coast than Peter from Dawe Motorsport in Stroudburg Pa.Ciao Fred

?????

That's like saying if my mother had wheels she'd be a bike!!! You are talking about two different things here.

A drill bit is for drilling a hole. Would you agree? They make special tool bits for chamfering holes, would you also agree?

I find nothing wrong with the idea just how you are doing it. And, you put it out there as a tip on a DIY forum. Maybe you know how to do this with a drill bit, but maybe "Fred Smith DIY guy" doesn't and leaves burrs and has oiling issues to the bearing.

Was hoping you would leave a foot note to use the proper tool to do this mod (tip) and make sure no burrs are left.

Would a pro do this, with a drill bit?

Proper macine work
 

That is where you guys come in for the guidance.The funny thing about this business is most people think if you do this a lot it takes less time.Not true,every step for me is more knowledge & I have found it takes me longer as I have found ways you make each step more complete.So we always learn more.At my age we are fighting dementia.Happy 4th to all the Pelican Forum.Fred

Fred, Deiter has a place near us and is still building an engine or two. I usually see him around the hillclimb. I'll tell him you said hi.

I think you make a good point. All DIY procedures regarding something as expensive as an engine should be vetted/approved as regards to methods by someone with experience. I'd use my extremely sharp no-one-else-can-touch Hanson bits for this without batting an eye.

Regarding bearings in general. The new idea is bearings that are purposely slightly oval when cold, becoming exactly round when heated.

That's been done for decades on Detroit iron. Also chamfers on crank holes. A sharp bit works ok, a multi-flute countersink would be better. If you don't feel comfortable doing free-hand a jig can be set up on a drill press to hold the bearing and then you can set exact depth you want bevel with the stop on the drill press.

http://forums.pelicanparts.com/uploa...1499000721.jpg

m42racer, what do think will happen if you leave a burr in the oil hole?

What do you recommend, a countersink or countersink drill bit? Both have 2 flutes like a standard drill bit.

What depth? Perpendicular to hole, or at an angle to the perpendicularity of the hole?

Doing this work needs to be done with care and some thought.

If you are using a drill bit and a bit that is sharp and new, it will have an included angle of approx 120°, just under. It has two cutting faces as well. So you will create a large major diameter at a lesser angle than a 45° countersink bit will. Some may look at that and feel it is not deep enough and keep on going until the bearing shell is compromised. The lessor of an angle will make doing this work harder as the bit will want to bite into the bearing if you are not careful. This is when the burrs will happen.

As for the burrs and rough faces of a drilled countersunk hole, have you not seen how a liquid travels through a hole like this verses one without burrs?

There are quite a few sharp edge transitions between oil pump and eventual exits. Hand or machine chamfering every one might provide some flow optimization but I doubt it's measurable.

This is more about not deforming the bearing by pressing to hard (most people know to let the bit do the work). And not leaving a raised area on back of shell, causing a high spot to wreck crankshaft.