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crankshaft worries |
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xspiriment
AMC Nut Joined: Apr/27/2009 Location: New Mexico Status: Offline Points: 379 |
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Posted: Dec/04/2021 at 3:46pm |
Well i received my crankshaft back from the machine shop i sent it to. He did everything that i wanted done. I had a 401 crank destroked to 3.566 and 2.100 journals. I have never built an engine with a detroked crank. I didn't consider how much the oil holes would move and thats what worries me. Someone that has gone through this before what are my options do i need some kind of correction. My only thought is to put a little more chamfer towards the journal center if needed. Look at my pics and tell me your thoughts, am i OK the way it is or extra work needed. Thanks
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PROSTOCKTOM
Supporter of TheAMCForum Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2458 |
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I see nothing wrong with it, but wonder why you would destroke a 401 crank?
Tom
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Molnar Technologies Full Service Dealer - Crankshafts & Connecting Rods
1969 AMC Rambler Rouge Race Car 1974 AMC Hornet Hatchback, Wally Booth Outlaw Nostalgic Pro Stock Race Car Project |
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5480 |
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Those don't look bad. If you are worried about the mains, you could have channels like these put in.
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xspiriment
AMC Nut Joined: Apr/27/2009 Location: New Mexico Status: Offline Points: 379 |
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Hi P/S Tom, This is what i ordered the 6" rods for from you a few months ago. It all started many years (20) ago and i was thinking about rod length ratios and bore to stroke ratios. It all looked good on paper so i am now moving forward with this plan. i could never seem to get my hands on a 401 block so this is going in a 360 bored at 4.125. 401's blocks are to hard to fine here in new mexico. This crank had a big gouge in#2 journal so it seemed to be a good choice to destroke this one. I get 381ci out of this combination. Have a custom bullet solid cam. 291C heads and a new torker bought in the early 80's. Planting this in a 79Spirit AMX. It's enough engine for me. Paul
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DragRacingSpirit
AMC Addicted Joined: May/27/2009 Location: Mo Status: Offline Points: 903 |
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I don't see anything wrong. I think it looks fine. No different than my 3.9 stroke 401 cranks...and I have never had a rod journal bearing issue. I am running them at 750 horse and 7600 rpm and a 2" journal. I assume that a de-stroke is stronger than a stroke because there is more journal overlap.......especially with a 2.1" rod journal size. That should be one strong crank....although personally I would never de-stroke a crank. IMO you should have shot for a 3.8 stroke with a 2.100 journal size. Proven a good combo over and over again in high hp applications using a stock crank! All of that rod ratio stuff is a bunch of crap. The correct rod length is the one that the pistons clears the counter weights and gives you room on the pistons for a reasonable ring package.
Edited by DragRacingSpirit - Dec/04/2021 at 8:55pm |
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Best 1/4 mile 8.99, 1/8 mile 5.71, 60 foot 1.27, no power adders
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xspiriment
AMC Nut Joined: Apr/27/2009 Location: New Mexico Status: Offline Points: 379 |
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Thanks for your encouraging words that its ok. This has been a very slow build so the ratio is something i read a lot about long ago. Any way i now have a forged bottom end stuck in a 360 block, oh well it should work fine. I have one flat flange 401 crank left in my stash of parts. Probably won't ever use it. Thanks all
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