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#1
02-03-2013, 12:41 AM
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Offset grind crank
Wanting to offset grind my factory 455 crank to BBC size to increase stroke to 4.25. Not normally a problem but the crank has a fresh unused .010" grind on it. This would leave one side of the journal untouched, not ideal in any world. My question is can I have the journal machined to BBC minus .010" without causing any issues or problems with availability of bearings. I know the purchase of a new crank already at this stroke is probably the thing to do but living in Oz the cost of freight scares me somewhat and I already have a perfectly good crank that I would like to use, any thoughts would be appreciated.
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#2
02-03-2013, 01:26 AM
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You should have no problem stroking it .040 and using a .020 oversize BBC bearing. You should have no problem getting .020 over bearings. Just make sure you have a good crank grinder he puts a nice radius on the journal.
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Tim Corcoran |
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#3
02-04-2013, 01:55 AM
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x2 on ensuring a proper radius. When removing excessive amounts the machinist may need to re-dress the stone radius more than usual. Some guys may charge extra for that. Some not.
__________________
1969 GTO hard top ~ Std bore 400, '70-RA3 block, 670 heads, Bal. & Blue... M22, 12-bolt w/3:55s |
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#4
02-04-2013, 09:07 AM
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I just remembered I have one of those. They were used before the influx of aftermarket cranks. I personally can't see the sense in doing one these days, unless shipping is serious $$$. The one I have was only able to be offset ground to 2.240.
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#5
02-04-2013, 12:21 PM
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X 3 on the radius! Are you SURE your crank is "on stroke" now? Have you measured it?
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“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
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#6
02-04-2013, 01:13 PM
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Seems like alot of extra expense since you have a fresh crank already and have the rods and pistons for the 4.21 stroke? ...i would leave it alone, unless you already have the bbc rods and right comp. height pistons.
__________________
 1963 Cat SD Clone (old school) streeter 1964 GTO post coupe, tripower, 4speed (build) 1965 GTO 389 tripower, 4 speed, driver 1966 GTO dragcar 1966 GTO Tri power, 4speed, barn find 1966 GTO Ragtop 1969 GTO Judge RA lll, auto 1970 GP SSJ 1970 GTO barn find..TLB…390 horse?….yeh, 390 1973 Grand Safari wagon, 700hp stoplight sleeper 525ci DCI & 609ci LM V head builds Factory stock oval track car |
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#7
02-04-2013, 09:22 PM
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Quote:
they were stuck in the Long Beach dock strike for several months whatever, that offset crank ended up costing me near what a new 4.25" -forged- crank can be had for now days.  Ive had fun with it but the stock 4.21 stroke would have done as well with less side load on my factory block.
__________________
  My Daddy bought me a car but all I got was this old Pontiac.
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