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401 Crank oil passages "wrong"? |
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xspiriment
AMC Nut Joined: Apr/27/2009 Location: New Mexico Status: Offline Points: 379 |
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Posted: Aug/28/2015 at 9:37am |
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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.
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Class Guy
AMC Addicted Joined: Jul/02/2007 Location: Arkansas Status: Offline Points: 969 |
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So a destroked 390 crank for a "high performance" 290-343 would be better than the stock crank? (besides being forged)
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5480 |
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amc67rogue
AMC Addicted Joined: Nov/05/2008 Location: Phx. AZ. Status: Offline Points: 1578 |
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From the factory 71 401s had half groove mains , 73 up were full groove. All the others 290 -390 were half groove. In the early to mid 70s all the after market replacement main sets had the full grove center main.
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Keith Coggins 67Rogue X code
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401jim
Supporter of TheAMCForum Joined: Jan/07/2012 Location: Brunswick,Ohio Status: Offline Points: 793 |
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Oh boy am I dizzy now! I think I will stick to the fully grooved mains and hope for the best. WOW!!!!!!
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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I haven't gotten to the point of sitting down to figure what it all means for crank position and the oil feed hole in the block.
I've also read a lot of different things concerning which engines got full groove, half groove & no groove main bearings. I wasn't thinking different mains got different bearings in the same engine. But to clarify, the hole location on the #2 main that feeds the #2 rod is different 401 vs 360/390 the hole location on the #4 main that feeds the #7 rod is different 401 vs 360/390 ^these two oil passages more closely mimic the 290/343 oil passages (which are all opposite from the 360/390) all other passages on my 401 crank were the same as all the 360's and the 1 390 I checked. Clear as mud? |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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Rebel Machine
AMC Addicted Joined: Jul/03/2007 Location: Western Il Status: Offline Points: 5121 |
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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 |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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Thanks Boris, yeah I think the engineers spent a little too much time thinking of that company on the other side of the lake, Buick was the wrong design to copy for sure, but it's the cranks that has me thinking. Up till now I thought the 390 crank had an advantage of better oil passages, and that still may be true, but wouldn't the 290/343 cranks be the worst of all since all their rod journals has the "right side to right side oiling" like the 'bad' #2 and #7 401 journals have? |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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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:
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 |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4210 |
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Oiling system failures in AMC products were
legion back in the day. But the stockers rarely if ever failed due to the drilling of the crank oil holes. The AMC oil system was a nearly exact copy of the worst oiling system of the day that being the Buick V8 and V6. AMC added a little plastic button on the bottom of the oil pickup that failed often and umbrella valve oil seals that shattered after the heat got to them blocking the oil returns in the heads. IMO the oil system was marginal even when working properly. |
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Gremlin Dreams
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