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#21
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We ran the Grocery Getter wagon for years with a stock block 455 and an N cast crank. 3 different blocks. After years and years of running around 1000-1100 HP. Zero broken or cracked N cranks. Ended up with 3 broken blocks. All cracked through the #2 main oil feed hole up to the cam tunnel. But our combination was a little different than yours. We had 5 billet main caps. Also aluminum connecting rods. But we ran it to 7500 rpms hundreds of times with a manual transmission and did 15-20 second 1/8 mile burnouts @ 7000 RPM's. Man, that was fun. IMO, with 4-bolt main caps, the crankshaft will be the last part to fail. Rods first, then the block, last the crankshaft. I have never run big HP with a 2-bolt main cap Pontiac. So can't help you on that part.
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#22
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I had an issue with cap walk at 2 and 3 at a lower level than what your trying to build in a .060 over 469 at 6500. I ended up putting the the available longer dowel pins for the main caps to help tighten everything back up.
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Illinois Outlaw Gassers 6.27@107 9.97@131 |
The Following User Says Thank You to Bill Eveland For This Useful Post: | ||
#23
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We ran a 455 with stock crank, stock 2 bolt main caps and bolts, Eagle rods and Ross pistons. All steel 67 GTO w/ full interior and 9" slicks. Best was 10.51 @ 127. Shifted at 6300 and went through the traps about 6700. And although we didn't race every weekend, we did it for years.
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#24
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It’s very easy to tell if a 100% polished out crank is cast or steel.
Drill a shallow 3/16” hole in the the flywheel end of the crank as close as you can get it to the crank centerline. If the crank is cast you’ll drill out chips, if it’s steel you’ll get long shards. My bet is since you say it has a center square cheek that it’s a factor nodular iron crank.
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I do stuff for reasons. |
#25
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Quote:
I did do the drill thing years ago. Scat forged came out as spirals. OEM cast came out very small chips, powder like. This crank had a bit larger pieces than the PMD cast crank. I am thinking it started out life as a Eagle cast steel crank since they did not weld up the thrust with Ni rod-wire. |
#26
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I would like to modify my answer as I misunderstood the question. Your crank is good for a lot more power than you're are asking about. The two bolt main caps are the week link at your power level. Anything you can due to reduce reciprocating weight will help along with main studs and over size main cap locating pins.
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#27
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Easier to say larger dowel pins
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#28
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The transmission alignment dowel pins?
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#29
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Factory 2-bolt Main Caps will be fine with NA and well-Balanced. sure there are better tings.
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#30
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You're probably right, all the way until the number two main cap separates and becomes two one bolt caps.... and assuming you don't mind some main cap fretting
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#31
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So Mike S ( the OP) your good to go it seems!
Half inch stud will guarantee you that up at the 700 hp level with your motor being NA with its two bolt caps, that a good balance job is the ticket to keeping it all together!
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I do stuff for reasons. Last edited by 25stevem; 12-08-2022 at 07:27 AM. |
#32
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Well no, but saving money on a 1/4 mile grenade is a balancing act. Post #21 reads well to me.
Whatever the ECM does is the right answer, if you got the money to pay out for that solution. I don't. See, i went with Studded and redoweled Steel MainCaps awhile ago: the Block showed a split up #2 web. Must have been the heavy TRWs, SD Rods and typical sized balancer. And the steel mounts. I bought a 2-bolt drilled 455 block, cast caps stock bolts that had several hundred high rpm rounds in the low 9s. Inspected well. Sold it last year to a fella that will race it. Had/has aluminum rods and super light sbc 400 slugs and thinwall 927 pins. Midplate and front plate seem to be the economical feature that keeps the main webs intact. |
#33
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Lots of good stuff here, I use longer bigger dowls I make my own
two bolt studded mains and alluminium rods and a good bal job. My allum rod 464 SM headed motor seen 7000 quite a bit with no prob's GT. |
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