Re: How big can you bore a 1969 426 Hemi block??
[Re: StevieD1966]
#2638962
03/30/19 07:22 PM
03/30/19 07:22 PM
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Joined: Aug 2003
Posts: 43,882
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,882
Bend,OR USA
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The ring packages available for the stock 4.250 bore is some what limited but it is the same bore size as the 427 Chevy and 383 motors. The stock 440 bore is 4,320 which is +.070 over 4.250 so ring packages should be good for your deal. I've seen a lot of stock 426 blocks bored to 4.320 for NHRA SS back in the day and some even bigger on good blocks before Mopar started offering NHRA approved replacement blocks in the 1990s  Before deciding make sure and have it sonic tested by a good shop and go from there, I like to see at least .180 or more on both the major and minor thrust surfaces after boring honing  Some of the stock production blocks have a lot more than that stock(.330+) and some don't have as much as others 
Last edited by Cab_Burge; 03/30/19 07:23 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: How big can you bore a 1969 426 Hemi block??
[Re: RUNCHARGER]
#2638977
03/30/19 08:15 PM
03/30/19 08:15 PM
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Joined: Sep 2014
Posts: 9
Virginia Beach VA
StevieD1966
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OP
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Posts: 9
Virginia Beach VA
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Thanks!! New blocks are hard to find. Tons of them have been bored .070, have it sonic checked and then you'll know.
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Re: How big can you bore a 1969 426 Hemi block??
[Re: Cab_Burge]
#2638978
03/30/19 08:16 PM
03/30/19 08:16 PM
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Joined: Sep 2014
Posts: 9
Virginia Beach VA
StevieD1966
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OP
member
Joined: Sep 2014
Posts: 9
Virginia Beach VA
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Great Thanks for the info! The ring packages available for the stock 4.250 bore is some what limited but it is the same bore size as the 427 Chevy and 383 motors. The stock 440 bore is 4,320 which is +.070 over 4.250 so ring packages should be good for your deal. I've seen a lot of stock 426 blocks bored to 4.320 for NHRA SS back in the day and some even bigger on good blocks before Mopar started offering NHRA approved replacement blocks in the 1990s Before deciding make sure and have it sonic tested by a good shop and go from there, I like to see at least .180 or more on both the major and minor thrust surfaces after boring honing Some of the stock production blocks have a lot more than that stock(.330+) and some don't have as much as others
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Re: How big can you bore a 1969 426 Hemi block??
[Re: Dragula]
#2638988
03/30/19 08:44 PM
03/30/19 08:44 PM
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Joined: Mar 2019
Posts: 24
PA
1118Steve
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Joined: Mar 2019
Posts: 24
PA
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.060 is pretty much standard on those old blocks. Got several of them here, been racing Hemis for close to 50 years. We started at Std., then went 020, 030. and 060 and then sleeved them back to standard. The one in the car now is .060 over. Most of them are. Most of the used old blocks you'll find around are 60 over. Years ago, Herb McCandless was marketing 70 over pistons, but, for some reason it never really took off. Sleeving is expensive. But, a Hemi block is worth it.
Last edited by 1118Steve; 03/30/19 08:48 PM.
"Old Age and Treachery beats youth and enthusiasm"
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Re: How big can you bore a 1969 426 Hemi block??
[Re: Dragula]
#2638989
03/30/19 08:50 PM
03/30/19 08:50 PM
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Joined: Jan 2003
Posts: 10,150
Frostbitefalls MN (Rocky&Bullw...
gregsdart
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,150
Frostbitefalls MN (Rocky&Bullw...
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I ran a 426w block at .100 over for years, till i drove over the crank!😢
How bad are the bores now? If they can clean up at .002 to .003, you could go with .060 + .005 rings and pistons made to fit? If you only have one or two bad cylinders, you could sleeve them and bore to match? Do anything you can to keep the bore from having to be bored to the next size, to add life to the block!
8.582, 160.18 mph best, 2905 lbs 549, indy 572-13, alky
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Re: How big can you bore a 1969 426 Hemi block??
[Re: StevieD1966]
#2639177
03/31/19 12:15 PM
03/31/19 12:15 PM
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Joined: Dec 2006
Posts: 2,140
Byron, NY
W.I.N. Racing
top fuel
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top fuel
Joined: Dec 2006
Posts: 2,140
Byron, NY
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My last Iron motor was .070 over.
'01 P1500, Blown/Inj BAE,/Veney ,Bruno/CS2,Dana 60
'01 Dodge 3500 S Cummins Auto, Fresh air kit, 4" Exhaust,
'05 Dodge Magnum R/T - Too Much to list
'60 Willys CJ5
'01 International LPX - Project,DT466, Allison
'64 Plymouth Valiant, Inj 528 Hemi, 2spd
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