Here is some interesting reading:



http://www.rehermorrison.com/techTalk/51.htm

I don't know if it's true or not but that is why I didn't have my crank crossdrilled.

Thousands of cross drilled cranks have been, and are being run without issue to this day. May not be optimal in a 9000 RPM 283, but for lots of engines, it's another non-issue. This is not new thinking BTW. My crank came cross drilled, I guess I should just get ready for my rod bearings to fail. NOT!:)

wether its cross drilled or not check every last passage for bits of metalic dust/crud Ive seen a few with oil/grease packed passages full of metalic dust/crud from the manufacturing process that appeared as thou they were taken dirrectly off grinding and pollish stage, sprayed with grease and packed with zero thought to removing metalic crud/cleaning

BTW that goes for internal oil passages in BLOCKS also

it is not a problem just need to use high volume oil pump, this use to be done in high rpm engines, one way around cross drilling was to machine block for two upper main bearings and it gave you 360 deg of oiling, today you can buy full groove bearings without having to machine block. tony.

it is not a problem just need to use high volume oil pump, this use to be done in high rpm engines, one way around cross drilling was to machine block for two upper main bearings and it gave you 360 deg of oiling, today you can buy full groove bearings without having to machine block. tony.


The problem with doing that is, you greatly reduce the load carrying capacity of the bearing.......not good. A better solution is to use 3/4 groove main bearings. More flow, no loss of load carrying capacity........all good.

Full groove bearings and even the so-called 3/4 groove bearings are a bad idea. The survival of the crankshaft is dependent upon a "wedge" of oil between the crank pin and the bearing surface. Fully grooved bearings disrupt this oil wedge. The "3/4 groove" or "extended groove" also disrupts the oil wedge, just not to the extent that a full groove does. Stick with 180 degree main bearing grooves and go fast. In my opinion, the jury is still out, as far as the cross drill issue goes. GM cross drilled all (or almost all) of their high performance cranks for many years and this issue could very well be debated to the same degree that high volume oil pumps have been in this and other media.

Full groove bearings and even the so-called 3/4 groove bearings are a bad idea. The survival of the crankshaft is dependent upon a "wedge" of oil between the crank pin and the bearing surface. Fully grooved bearings disrupt this oil wedge. The "3/4 groove" or "extended groove" also disrupts the oil wedge, just not to the extent that a full groove does. Stick with 180 degree main bearing grooves and go fast. In my opinion, the jury is still out, as far as the cross drill issue goes. GM cross drilled all (or almost all) of their high performance cranks for many years and this issue could very well be debated to the same degree that high volume oil pumps have been in this and other media.

No, 3/4 (not so-called, they ARE 3/4 groove) groove main bearings are NOT a bad idea. If you actually look at one, you'll see the extra grooving extends only an extra 1/8 at the "top" of the shell, on each side, totaling the extra 1/4. There IS NO LOAD capability involved at the top edges of that bottom shell, it is essentially vertical in that location. The load is basically all taken at the bottom........you guessed it, 1/4 or so. So, 3/4 groove mains give you more oil flow with no loss of load carrying capacity. You get the full wedge of oil between the crank and bearing right where it counts........it's all good. Going this route takes the uncertainty out of the whole deal. And you don't have to worry about trying to use a cross-drilled crank in an effort to get more oil to the rods, which has the potential to backfire on you and burn up your bearings.

[quote="540 RAT"]Here is some interesting reading:


http://www.rehermorrison.com/techTalk/51.htm[/quote (http://www.rehermorrison.com/techTalk/51.htm[/quote)]
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Not only excellent information but information that has been around & known to most performance engine builders for years.

One of the cars I drove for about 8 years in the 70's & early 80's went through exactly this same thing with the first "race crank" that went into it.
Lost every bearing in the engine first pass
Nothing changed except for the trick cross drilled crank.

This was a reasonably respected small block TAD that belonged to S&S Automotive (George & Rick Santos) & it started life with stock GM cranks (and blocks) which did not have a real long life expectancy,,,,
But they did not have bearing issues with the stock oiling & yes these did go through the lights at a "fairly high" RPM :D

It has been proven time & again that cross-drilled cranks are not necessary & usually not a good idea in most race engines in almost all cases & especially in hi RPM engines.
There are exceptions as was noted in the article

Don't believe it??
Ask Bryant, Winberg, Callies,,, the list goes on.
Also, it begs the question,,, exactly what is it you are "fixing" with the cross-drilling?


But,,, cross-drilling does have real advantages in Diesel engines as well as any other low RPM big main engine, which is where this "technology" came from ;)

Good info Mike, thanks.

Just for information purposes, Eagle does make a standard oiling crank for the ever popular 383. I just bought one 3 weeks ago, Part No. 435037515700 4340, internal balance, 5.7 minimum rod length.

I'm glad this came up. My buddy called me today worried that he might have a problem. He's been having horrible crank problems with balancing and exchanging cranks, etc... The replacement crank that showed up was not a cross-drilled crank like it was supposed to be. He was anticipating more drama/problems getting this one replaced. When I told him cross-drilled cranks were unnecessary and in some instances a bad idea, you could just hear the relief. Hell, I felt like a doctor telling his patient the biopsy was negative. :D

I remember someone (maybe Joe Reath) telling me that they drilled into the crank snout to the oil passage on a cross drilled and standard crank, and attached a gage to the end of each while running a dyno test. The standard crank had the least oil pressure fluctuations. The person who told me that suggested that cross drilling was probably ineffective. That was information from the 60's. Quess oil, cranks, and the laws of physics haven't changed much since then. I believe the proper chamfering of the oils holes in the crank is more important than any of the other related crank/oil stuff.

The sleeve bearing gets it's load carrying ability from it's width. Anything that removes the width of the oil cushion/wedge, removes the load carrying capacity of the bearing. That means grooved bearings or grooved cranks are a no no. Don't ever let anyone talk you into doing any form of grooving. The part will be trash.

Grooving is one of those ideas like Scotch brighting bearings before you use them. Been around forever for no good reason! (Why not put a piece of rock in each cylinder to help grind the valves in. That's how my uncle used to do it and he won races all the time.)

I didn't say I didn't believe it, I do. My opinion is for most engines, including mine, it just does not matter whether the crank is cross drilled or not. Correct me if I'm wrong about that. I did not specify cross drilled or not on mine, because I didn't have a preference.

jbird: You are missing David Reher's point: it does matter. My comment was that it may cause oil pressure fluctuations, and that is something you are trying to get rid of by crossdrilling, not cause by crossdrilling. If Reher says don't do it, it probably shouldn't be done.

Sometimes, logic doesn't work with fluids. If it did, we would all be expert head porters.

I didn't say I didn't believe it, I do. My opinion is for most engines, including mine, it just does not matter whether the crank is cross drilled or not. Correct me if I'm wrong about that. I did not specify cross drilled or not on mine, because I didn't have a preference.
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Jay,
That wasn't addresed to you directly it was just general information that is first hand.
Here is some more
Back in the day... :D
I had a Vega with a 482" BB
This engine was in 3 different cars in different configurations over the years,
Had GM L88 rods with the GM Boron bolts which is argrably one of the best bolt you could get & a GM cross-drilled crank.

When this engine was shifted about 76-7800 it did not seem to have bearing issues.
I changed a few things & the shift point was raised to about 84-8600 & it crossed the stripe at about the same
5.13 or 5.38 gear depending on my mood,,, 32" tire Lenco 4 speed, 148-152 was the average MPH
You can do the math
It started getting very hard on rod bearings & was beating up the center main on occasion.

I had a crank shop out here that did most of the fuel cars stuff add center counterweights & plug the cross-drilling at his suggestion.
Completly cured the bearing problem & seemed to help the mains a bunch.

Moal of story, cross-drilling can cause issues but I agree that for most here it is a non-issue but I don't recommend it.

Excellent info!!!!

"Ive seen a few with oil/grease packed passages full of metalic dust/crud from the manufacturing process that appeared as thou they were taken dirrectly off grinding and pollish stage, sprayed with grease and packed with zero thought to removing metalic crud/cleaning"

thats probably about what they do and, why shouldnt they? why waste time when they know any engine assembler worth his salt will do everything possible to get his parts all but surgically clean...even/especially when it already appears to be so upon removal from the box?

Gosh, where were all you guys when everyone was giving me grief for NOT crossdrilling the crank I put in my 427? My very trusted machine shop friend told me about avoiding crossdrilling and I listened because he's been doing this stuff for decade more than me (also used to be a serious racer) and to date he's never steered me wrong.