drilling main bearings

[Fletch]

Alfisti,
could anyone clarify for me....
on P233 section 1.5 of Pat Braden's Alfa bible,he mentions drilling the second and fourth main bearings for direct oiling.Has anyone tried this modification?How many extra holes should be drilled...I'm guessing one equidistant from the two already there?Are there any downsides?

Secondly,my mechanic is reluctant to use any form of sealant at the base of the liners,his argument being that they won't centre properly.I've read threads here strongly suggesting the use of sealant.
To seal or not to seal....?
Does anyone have anymore thoughts...?

Cheers,
Fletch.

[conedriver]

Hi Flech,

I have not done the additional bearing hole modification, but will do this the next time my '76 Spider engine is down for freshening. Perhaps others will chime in (like Turbolarespider, I know he did this to the block in the Grassroots Magazine challenge car).

I have done several normal rebuilds, and never use sealant on the base of the cylinder liners. Clean thoroughly, check for correct liner protrusion beyond the top deck of the engine, assemble, break-in, and then drive the snot out of the thing!

Quote:

Originally Posted by Fletch Alfisti, could anyone clarify for me.... on P233 section 1.5 of Pat Braden's Alfa bible,he mentions drilling the second and fourth main bearings for direct oiling.Has anyone tried this modification?How many extra holes should be drilled...I'm guessing one equidistant from the two already there?Are there any downsides? Secondly,my mechanic is reluctant to use any form of sealant at the base of the liners,his argument being that they won't centre properly.I've read threads here strongly suggesting the use of sealant. To seal or not to seal....? Does anyone have anymore thoughts...? Cheers, Fletch.

[ossodiseppia]

Street engines really don't need it. This mod is really for race engines. However, I had it done on my block. It's a little on the expensive side, but I think it's cheap insurance.

Four holes need to be drilled. One through each bearing journal and then two from the side of the block. You will need to take the block to someone that has done it before. It needs to be done right. The two holes on the side of the block need to be tapped so that plugs can be installed. After the machine work gets done, you will need to thoroughly clean all of the oil gallies.

[Wil Painter]

I copied these pictures last year and can no longer remember who posted them, so someone speak up and take the credit, I sure can't!
The photos from the front and rear show optional holes to drill, tap, and plug: they go thru the existing gallery plugs and allow easier and more thorough oil passage cleaning, but are not required as part of this modification.
The side photo shows the two spots that cross drill through the longitudinal oil gallery and intercept the vertical holes you'll drill up through mains 2 & 4. You'll also tap and plug these two holes on the side of the block.
The photo taken from the crank view shows the new vertical holes at 2 & 4 journals.
You'll also want to use main bearing shells with a circumferential groove at 2 & 4. I believe the Vanderwells are smooth at 2 & 4 (so won't work), and that Federal Moguls have the groove you want. Anyone else with further info on bearing selection pitch in. The upper bearing shell at 2 & 4 will have to be drilled and chamfered so that the hole lines up with the new journal hole.
As Osso says, when you're done clean, clean, clean!!
There's a shop here in Southern California that is jigged up to do this, as is Don Ereminas on the east coast (US). Both a long way from Jakarta.
Hopes this helps you visualize the modification.
Good Luck
Wil Painter

[ossodiseppia]

Quote:

Originally Posted by Wil Painter I copied these pictures last year and can no longer remember who posted them, so someone speak up and take the credit, I sure can't!

[genericwood]

Regarding bearings, the ones sold by International have #2 and #4 grooved like 1/3/5. I called to double-check before ordering last winter. Also, if anyone in the midwest wants to have this modification done, Bill at APEX machine in Bensenville, IL (right by O'Hare) is set up to do it. It is nice insurance for a race car.

Erik

[Fletch]

Thanks for the clarification Wil....looks like it needs some very careful planning,I'll try it on a scrap block first,as I'm not sure that the machine shops here are up to it!!
Regards,
Fletch

[Bill77]

Quote:

Originally Posted by ossodiseppia I am speaking up! That is my block.

[kenpo2]

Does anyone kwow who can do this crossdrilling of the crank near the Philadelphia area. My mechanic says a couple of machine shops have tried it on my crank and they gave up because they keep breaking bits. Tooo hard!!!!

[Wil Painter]

Kenpo:
You may be thinking of two different issues here.
Cross drilling the block is all in aluminium and easy drilling; the set-up trick is to jig and align so the holes intersect in the right places. On the other hand, the crank is definitely hard (as in both hardness and difficult), but not "crossdrilled" for this modification. Perhaps you are thinking of replacing the press/peened fit plugs in the crank with screw in plugs? This is difficult work and is done by some crank shops with carbide drill bits and slow, meticulous tapping with high quality, hardened taps. It's easy to break off a tap in the crank which really makes recovery a challenge. You are correct, many crank shops won't do this. Not impossible at home, but not for the faint of heart, the impatient, or those unwilling to invest in very high quality drill bits and taps.
Good Luck
Wil Painter

[borrani]

Yep, Int'l Auto Parts sells Federal Mogul bearings, which have that circumferential groove.

Wes Ingram's shop drilled out my block, here in Seattle, USA.

Steve S.

[turbolarespider]

Since George mentioned me- all I can say is that Will has all the right pictures. Nicely done.

IF you do it yourself (and I've heard it done at trackside a few times), make sure you get a drill bit that is designed for aluminum. They are a little different than the standard metal bit, and will make life a lot easier. And if you do it a lot, make jigs- when we drilled ours, it was mounted on a mill with a jig to hold the engine horizontally.

Like osso said, though, this isn't needed for a street engine. I'm pretty certain we did, though.

After doing it, you may want to shim the spring in the oil pump for some extra pressure- you are now feeding two more bearings. More flow would be better, but harder to do.

As for the sealing- we actually epoxied the liners in the block. The O rings do not provide any centering. If they did, your engine is in big trouble, and you would go through a lot of head gaskets since the liners would move around too much. Epoxying them in does provide a degree of block stiffening, and along the wire in the top of the liner, our engine was able to withstand 14 psi of boost at 8000 rpm, very briefly. The engine is still alive.

Eric

[BigSwede]

Two more bearings? How is that?

[turbolarespider]

Ok, bad wording.

Instead of oiling the 2 & 4 bearings through the arduous path up and back down the crank, they are now being directly fed, which will use more of the available oil flow.

how's that?

E

[BigSwede]

Will it really? Why would the bearing use twice as much oil because it is fed directly instead of through the crank?