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Discussion Starter #1
I have seen the words in the title of this thread a number of times.
I get the general reason for doing this. (more lub to the bearings)
But I have no idea how it is done, where the drillings are made,
as well as all the other parts that might need to be modified.
Also, can anyone explain (maybe a good guess) as to why Alfa Romeo
did not do this to all these engines? What is the down side of doing this if any?
 

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It is done to improve the oil supply to the rod bearings which get their supply indirectly from the main bearings.
It is a good question why Alfa did not do it as the cost of drilling 4 extra holes would be minimal during production.
 

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--ADMINISTRATOR--chiuso per ferie
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I had the discussion with Karen about this modification. It's not really necessary for a street engine. However, it did not add too much to the cost and I looked at it as cheap insurance.

Holes need to be drilled from the sides of the block. Then, holes drilled down to meet. The new passage ways need to be thoroughly cleaned out. Then, a couple of plugs put in the two holes drilled from the sides.

If you squint your eyes, you can see where the holes were drilled in the side of the block.

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Holes need to be drilled from the sides of the block. Then, holes drilled down to meet. The new passage ways need to be thoroughly cleaned out. Then, a couple of plugs put in the two holes drilled from the sides.
Not to insult anyone's intelligence. But there is one more step:

And, you need to drill holes in the upper halves of the #2 and 4 main bearing shells.

samakijoe said:
I get the general reason for doing this. (more lub to the bearings)
I'm not sure it even does that. If the oil passages inside of the crankshaft are working OK, the rod bearings and #2 & 4 mains probably get sufficient oil. I view adding these passageways as a "belt and suspenders" approach to crankshaft oiling; if one of the crankshaft passages gets clogged, there's an alternate route for oil to reach the bearings.
 

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" probably get sufficient oil" Yes, for a street car.
But at 9000 RPM on a race car car, maybe not.
I have been doing this to all the race engines I build. And have been doing it for close to 50 years.
I have had at least 2 Alfa factory blocks that were also drilled. Maybe by Autodelta.
When I worked at Prototype Engineering.
 

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Discussion Starter #6 (Edited)
OK boys and girls, I don't see the holes on the side of the block in picture #1. So how about some of you younger folks get your little red crayons out and circle the holes for the rest of us older guys with bad eye site. ...:cool:

And, was/is there any down side to doing this? (as in low(er) oil pressure??)

Even at low RPM, I can see where this would have been a good idea.

Do any other engine manufacturers (other then Alfa) design in full pressure oiling to all the bearings?
 

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Both my GTA blocks are drilled. One at Ausca the other by me. The first engine was heavily raced by me. The second was going to be a race engine block in my son's vintage racer until he decided to run Spec Miata. I installed it as a backup in my car, now only street driven while rebuilding the original.
 

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Here's the plugs visible on #2 main, as the blue anodized hardened aluminum plug. Theres another mon #4 in the first photo...

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Richard Jemison
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There`s a lot of info that isn`t commonly posted.

Why in hell did Alfa drill 1/3/5 from the dry (intake) side of the block? They had to drill all the way from the intake side of the block to the main oil passage on the left(exh) side of the block.
Only guess that their was an Engineer with an accountant in his face... :rolleyes::rolleyes:

Then their`s the guestions of 1930`s technology on oil pick-up hole elongment that would have in itself improved oiling to the rods from just the 3 main bearing points.

But there are some points that most are not aware of.
The oil pump only has "so much" capacity. At low speeds the pump cannot supply the oil volumn commonly deemed necessary particularly in street engines with oiling improvement as we are discussing. Drilling #2&4 and drilling a matching hole in a flat ("standard type factory bearing") helps oiling minutely, but to maximize oiling to the rod bearings using drilled 5 main bearings that are fully grooved (360 degrees) really improves oiling to the rod bearings as oil is picked up during the cranks full 360 degree rotation.
The downside is low oil pressure in such a build at low RPM. 20 lb or less at idle, but raising to normal as RPMs increase above 2 to 2.5K RPM. On a race motor this is not a problem. On a street motor a typical driver would be concerned.

Alfa actually built wonderful cars to improve on. Not so much from the assembly line.

You all know waht ALFA stands for right?
 

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Discussion Starter #10
What I find interesting is that the block casting included two robust areas that could be safely drilled and taped to commandant the addition of the oil feed to #2 and4. So there must have been investigation into the consequences of going ahead with providing additional oil flow to 2 and 4 but they decided that it was not needed in street engines and it would upset buyers seeing the low oil pressure at low engine RPM.

Has anyone found any Alfa Romeo Tech Bulletins describing this "up grade" or was this something that Autodelta kept to them selves as long as possible?
 

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Drilling #2&4 and drilling a matching hole in a flat ("standard type factory bearing") helps oiling minutely, but to maximize oiling to the rod bearings using drilled 5 main bearings that are fully grooved (360 degrees) really improves oiling to the rod bearings as oil is picked up during the cranks full 360 degree rotation.
Hmm - good point. Are grooved bearings, sized for mains #2 & 4, available?
 

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Yes, full grooved #2 & #4 bearings are available. Jon Norman (and others) sell them.
 

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Richard Jemison
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Both ACL and King "Black Series" race bearings can be bought in Standard and oversize
I`ve ordered from Summit and Amazon.

Their part # s:
Main Bearings:
King MB511XP and size (Std/.010 etc)
ACL 5M1112H """""""

Rod Bearings:
King C4595-PR & size
 

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Funny thing . . . this was never mentioned in the Competition Reference Handbook.
 

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There is a time frame here Jim. It was NOT done on the GTA engines at Ausca, but Ron N started doing it at Prototype with Ed Wachs. The Prototype special catalog I have in my files does NOT mention it though somewhere about that time they started doing it. My guess... only a guess.. is on the 9,000 rpm GTA Jr engines first as those gave Ron N grief at Ausca with oil pumps. He made these bottoms that I make now...
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At Ausca neither the alloy or tooling existed to make these work as intended. Dave Brengle kindly provided me a failed one from his mom's spider race car engine Ron built. I did a computer scan and had a solid carbide cutter made to cut gear bores. I think you and I discussed the alloy, pretty heavy for aluminum and tough as steel. I've forgotten the number. The resulting pump with helical gears did not suffer idler pin tilt at the Jr's 9,000 rpm. Here is one I built for a Besic "long-rod" 1600.
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These went along with Ron Neal's Jr engine builds drilled as 5 oilers.
Neat historical Alfa race stuff.
 
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