401 Crank oil passages "wrong"?

Something that I did to a 360 crank back in '79' was to file grooves across each oil hole on the crank about 1" one the mains and 3/4" on each rod journal. Pick up this idea from a Porsche crank. Can't really say if it improved bearing lubrication, but I never had a any problems with that engine. I still have that crank and it looks good, getting ready to build a new 360 with that same crank. Google Porsche 914 crank images and notice the grooves, seemed to do no harm to my engine.

401jim wrote: Oh boy am I dizzy now! I think I will stick to the fully grooved mains and hope for the best. WOW!!!!!!

Time to bring up the internal oil line debate again?......

Oh boy am I dizzy now! I think I will stick to the fully grooved mains and hope for the best. WOW!!!!!!

This is interesting. I'm going to look over some of my cranks and see if I can wrap my head around this. Looking at some pics from previous builds the main #3 bearing has the oiling groove in both the top and bottom but mains 1, 2, 4 & 5 only the upper main bearing has the oiling groove. If all cranks were drilled dead center from main to it's respective rod it would seem the odd number rods fed by all mains other than #3 would oil ATDC and the even number rods fed by all mains other than #3 would oil BTDC. Rods (4 & 5?) fed by main #3 would oil 360 degrees.

I guess offsetting the passage tries to get those non #3 main fed odd numbered rods closer to BTDC oiling?

I'm probably missing something.

-Steve-



Edited by Rebel Machine - Aug/23/2015 at 9:50pm

OK,
 I found the other thread that goes into depth on this:

http://theamcforum.com/forum/390-cranks_topic67162.html?

and the info I found with my own cranks today that conflicts with this is:
 my (73) 401 crank has journals 1,3,4,5,6&8 drilled identically to the 360/390,
 it was journals #2&7 that were different, mimicking the 290 journals, only with slightly less angle & less chamfering.



In that thread I did ask and get a good answer there from Hurst390:

Hurst390 wrote: jpnjim wrote: Great thread! I've been meaning to start a 401 crank oiling discussion (and HOPE it would be this informative) So the main part of the 401 crank problem is ONE journal's oil passage is drilled backwards so the oil flow has to fight inertia as it oils the journal (correct?)  A 401 amc crank oils #6 rod ADTC. The oil has to go straight down out of the block,enter the #4 main journal and make a hard right angle back up to oil #6 rod journal AT THE WRONG TIME. It also has this scenario at #1 rod. But #1 main only has to oil the #1 rod bearing...not 2 rods like the other 4 mains. So #4 main becomes an issue. Endurance will kill it. even with a dry sump eventually. A 390 crank is drilled so that each rod gets its oil coming up on tdc when it needs oil. A 400 chevy crank oils correctly

But after rereading it I just went and double checked my 73 401 to the 68 390,
  1,3,4,5,6 and 8 (including journal #6) are drilled identically
it's 2&7 that mimic the 290/343.

I am certainly not trying to call anyone out thats been doing this stuff (and doing it very well!) for 20-30-40+ years,
 just trying to get the facts straight & wrap my head around it.

I have a 77' 401 crank tucked away.
 My next step will be to dig that out and see if that is drilled the same as the 73 401 crank.

Thanks