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AMC Entry for Engine Masters 2015?!?!?! |
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SKeown 
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Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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 Posted: Apr/25/2015 at 10:49pm |
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Wouldn't it be better to use a 401 block for the additional strength and clearances already designed into it? We are talking about the center line of the rod journals coming .160 closer to everything which shouldn't be a problem in a 401 block with aftermarket rods which are less bulky than OEM. Sleeving a 401 block to a 4.060 bore may not require removing the entire original cylinder wall? If so then that in addition to the beefier block webbing would make for a better/stronger engine with adequate clearance for the longer stroke. I've never had a block sleeved, so I'm asking. Having a raw crank forging is definitely a good thing, being limited to the small bore is a real bad thing. SKeown
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SKeown
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Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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Posted: Apr/25/2015 at 11:17pm |
The .017 longer 360 rod than the 401 and using a .927 diameter wristpin instead of the 1" will put the piston .1165 closer to the crank than the 401 has. That doesn't leave a lot of meat under the wristpin. You could go to even a smaller wristpin but it wouldn't help much. That's why I suggested having Oilver make some 6" rods with an AMC big end and Chevy pin end. The 6' length with a 4" stroke will allow adequate clearance for everything, a nice CH piston while maintaining a 1.5 rod ratio. The 401 has a 1.59 rod ratio, and by going to a 6.125 rod length only improves the ratio to 1.53 while reducing the piston's CH substantially. Maybe Tom Molnar would be willing to do a one of set of rods for such an endeavor? SKeown
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Slate
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Joined: Feb/28/2012 Location: Airyzona Status: Offline Points: 2784 |
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Posted: Apr/26/2015 at 12:00am |
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I got a set of 6" rods, within the .035 on the crank pin allowance, and .928 piston pin size. Brand new. Would they work?
Steve |
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SKeown
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Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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Posted: Apr/26/2015 at 3:07am |
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From what I've read here the rules only allow a .030 reduction from the original crank's journal diameter. It would be terrible to be disqualified over something like a journal diameter infraction. That's why I question weather a 360 journal would be allowed on a 401 crank, and feel doing the crank with the 2.248 rod journals would be safest. I've seen no stipulation regarding the rod's length, but maybe something other than a shelf available rod would be frowned upon? If so, that would prevent a custom made set from being used unless Molnar made a run of them. The rules don't favor us at all. It seems everything other than the displacement and how that's achieved is pretty cut and dried. SKeown
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Slate
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Joined: Feb/28/2012 Location: Airyzona Status: Offline Points: 2784 |
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Posted: Apr/26/2015 at 9:47am |
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I just wanted to know if a rod that appears to be slightly bigger than a 360 journal would work. The actual finished size based upon the dimension on the box, appears to be about .0025 to .005" large. But I'm no engine builder. I'll give the specs to Lynn and he can figure if it would require thicker bearings. I gave the wrong impression by using the contest allowance for undersized limits to be a +/- tolerance.
As to grinding or welding a 401 crank to 360 rod size, Lynn has no worries , so I'm not concerned. I think that you are reading into the rules a bit too conservatively. From what I can see about the intent of each technical rule as written, unless specifically prohibited, such as the rule that no billet cranks are permitted, then you can use a 401 crank ground to 360 rod pin size. Why? Because the 360 is an original AMC design. The rules don't say that the commercially available crank has to maintain its own original rod journal size. It just has to be one of the sizes AMC originally used. Steve |
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Boris Badanov
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Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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Posted: Apr/26/2015 at 9:55am |
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Welding and grinding a 401 crank makes the most sense.
those raw forgings are way cool but will cost big $$$ to finish.
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Gremlin Dreams
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Slate
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Joined: Feb/28/2012 Location: Airyzona Status: Offline Points: 2784 |
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Posted: Apr/26/2015 at 10:13am |
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Lynn can weigh in on the cost. I re-read the rules and as stated I see where SKeown and others are coming from on the 360. I think I was being too lose with my statement about any production AMC journal size applying. More accurate is to say that the rule requiring no greater deviation than .035" + or minus from the claimed engine the crank is going into still allows the 401 crank in a 360 block. -.035" from a 401 crank is a 360 journal dimension. You could still go another .035" in theory and be alright. Since he'd be using a "360" crank in a 360 block he'd meet the rule requirement.
Nowhere do the rules state that the crank had to start out with 360 rod dimensions or that a 401 forged crank can't be used in a 360 block. It can be ground down to 360 size or even be original 401 rod journal size and still be within the .035" rule for a claimed 360 block. Steve |
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401jim
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Joined: Jan/07/2012 Location: Brunswick,Ohio Status: Offline Points: 793 |
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Posted: Apr/26/2015 at 10:27am |
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Off grind the 401 to get as much stroke out of it as possible. Grind to 360 rod specs and use a 360 forged rod. You can get a custom rod length to accommodate stroke. Still in on this! Don't have too much time to get an entry in.
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Hurst390
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Joined: Apr/20/2008 Location: secret Status: Offline Points: 5818 |
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Posted: Apr/26/2015 at 11:25am |
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A std. 360 rod journal is only .006 smaller than a 2.100 chevy journal.I believe if I've read here correctly that would be within their rules? Rod width would be the only factor with the rules unless you used the Rick Jones 360 stroker rod...
I have a 3.8 stroke 401 crank with a 5.850 rod and there is barely enough clearance between the piston and crank counterweight for it to work..so as stated crank to piston clearance is an issue with a 5.850 rod with a longer stroke.. Edited by Hurst390 - Apr/26/2015 at 11:30am |
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SC/Hurst Rambler
11.62 120 100% Street Legal |
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Slate
AMC Addicted
Joined: Feb/28/2012 Location: Airyzona Status: Offline Points: 2784 |
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Posted: Apr/26/2015 at 11:50am |
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You are correct. The width isn't t a concern other than wear/failure worries.
Revisiting the lifter rules, it pays to read them! Now Lynn's comment about what the others are limited to makes sense. With the exception of Mopar, they are all smaller because they are a Comp spec part for each manufacturer . The Olds is a .842", for example. Chevy, fuhgit about it. Steve |
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Slate wrote: