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How big can you bore a 1969 426 Hemi block?? #2638933 03/30/19 06:55 PM 03/30/19 06:55 PM
Joined: Sep 2014 Posts: 9 Virginia Beach VA StevieD1966 OP member
StevieD1966 OP member Joined: Sep 2014 Posts: 9 Virginia Beach VA	I have a 1969 426 hemi block that is bored 60 over now. Can you go larger than 60 over and have special pistons made??

Re: How big can you bore a 1969 426 Hemi block?? [Re: StevieD1966] #2638935 03/30/19 07:06 PM 03/30/19 07:06 PM
Joined: Jan 2003 Posts: 1,374 Houston,Tx. L Lee446 pro stock
Lee446 pro stock L Joined: Jan 2003 Posts: 1,374 Houston,Tx.	The only sure way to find out is to have the block sonic tested.

Re: How big can you bore a 1969 426 Hemi block?? [Re: Lee446] #2638946 03/30/19 07:29 PM 03/30/19 07:29 PM
Joined: Sep 2014 Posts: 9 Virginia Beach VA StevieD1966 OP member
StevieD1966 OP member Joined: Sep 2014 Posts: 9 Virginia Beach VA	Thanks, I'm taking the block on Monday to have it tested. I'm still wondering if anyone has bored a block more than 60 over?

Re: How big can you bore a 1969 426 Hemi block?? [Re: StevieD1966] #2638951 03/30/19 07:51 PM 03/30/19 07:51 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Check to see if you can find rings.. pistons can be made to any size

Re: How big can you bore a 1969 426 Hemi block?? [Re: StevieD1966] #2638952 03/30/19 07:52 PM 03/30/19 07:52 PM
Joined: May 2004 Posts: 12,388 Taxes & Virus's R-US, NY Dragula I Live Here
Dragula I Live Here Joined: May 2004 Posts: 12,388 Taxes & Virus's R-US, NY	.060" is about it...You can sleeve it though....I had one with 8 sleeves...ran it for years. My engine guy can do it so you can't even tell. '70 Cuda,...605 EFI Hemi Street Car (6.20 best pass, 1.33 60ft) https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car) https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car) https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9) '66 Barracuda AWB Stretched nose Blown 440 Car in build stage '71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph https://www.youtube.com/watch?v=Znuo3jMUXTk

Re: How big can you bore a 1969 426 Hemi block?? [Re: Dragula] #2638955 03/30/19 07:59 PM 03/30/19 07:59 PM
Joined: Sep 2014 Posts: 9 Virginia Beach VA StevieD1966 OP member
StevieD1966 OP member Joined: Sep 2014 Posts: 9 Virginia Beach VA	Thanks, What would it cost to sleeve all 8 cylinders? Is it cheaper to buy a new block or can you find a new block?

Re: How big can you bore a 1969 426 Hemi block?? [Re: StevieD1966] #2638958 03/30/19 08:07 PM 03/30/19 08:07 PM
Joined: Jan 2003 Posts: 15,976 Chilliwack B.C. Canada R RUNCHARGER I Live Here
RUNCHARGER I Live Here R Joined: Jan 2003 Posts: 15,976 Chilliwack B.C. Canada	New blocks are hard to find. Tons of them have been bored .070, have it sonic checked and then you'll know. Sheldon

Re: How big can you bore a 1969 426 Hemi block?? [Re: StevieD1966] #2638962 03/30/19 08:22 PM 03/30/19 08:22 PM
Joined: Aug 2003 Posts: 43,176 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,176 Bend,OR USA	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 08:23 PM. Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: How big can you bore a 1969 426 Hemi block?? [Re: RUNCHARGER] #2638977 03/30/19 09:15 PM 03/30/19 09:15 PM
Joined: Sep 2014 Posts: 9 Virginia Beach VA StevieD1966 OP member
StevieD1966 OP member Joined: Sep 2014 Posts: 9 Virginia Beach VA	Thanks!! Originally Posted by RUNCHARGER New blocks are hard to find. Tons of them have been bored .070, have it sonic checked and then you'll know.

Re: How big can you bore a 1969 426 Hemi block?? [Re: Cab_Burge] #2638978 03/30/19 09:16 PM 03/30/19 09:16 PM
Joined: Sep 2014 Posts: 9 Virginia Beach VA StevieD1966 OP member
StevieD1966 OP member Joined: Sep 2014 Posts: 9 Virginia Beach VA	Great Thanks for the info! Originally Posted by Cab_Burge 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

Re: How big can you bore a 1969 426 Hemi block?? [Re: StevieD1966] #2638986 03/30/19 09:36 PM 03/30/19 09:36 PM
Joined: May 2004 Posts: 12,388 Taxes & Virus's R-US, NY Dragula I Live Here
Dragula I Live Here Joined: May 2004 Posts: 12,388 Taxes & Virus's R-US, NY	PM me and I will give you his number... '70 Cuda,...605 EFI Hemi Street Car (6.20 best pass, 1.33 60ft) https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car) https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car) https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9) '66 Barracuda AWB Stretched nose Blown 440 Car in build stage '71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph https://www.youtube.com/watch?v=Znuo3jMUXTk

Re: How big can you bore a 1969 426 Hemi block?? [Re: Dragula] #2638988 03/30/19 09:44 PM 03/30/19 09:44 PM
Joined: Mar 2019 Posts: 24 PA 1118Steve member
1118Steve member Joined: Mar 2019 Posts: 24 PA	.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 09:48 PM. "Old Age and Treachery beats youth and enthusiasm"

Re: How big can you bore a 1969 426 Hemi block?? [Re: Dragula] #2638989 03/30/19 09:50 PM 03/30/19 09:50 PM
Joined: Jan 2003 Posts: 9,999 Frostbitefalls MN (Rocky&Bullw... gregsdart master
gregsdart master Joined: Jan 2003 Posts: 9,999 Frostbitefalls MN (Rocky&Bullw...	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..603 156 mph best, 2905 lbs 549, indy 572-13, alky

Re: How big can you bore a 1969 426 Hemi block?? [Re: gregsdart] #2639097 03/31/19 09:28 AM 03/31/19 09:28 AM
Joined: Jan 2003 Posts: 20,774 A collage of whims topside Too Many Posts
topside Too Many Posts Joined: Jan 2003 Posts: 20,774 A collage of whims	Had one already + .060 that went to + .062 after checking it, no problems. "Your mileage may vary"...

Re: How big can you bore a 1969 426 Hemi block?? [Re: StevieD1966] #2639177 03/31/19 01:15 PM 03/31/19 01:15 PM
Joined: Dec 2006 Posts: 2,110 Byron, NY W.I.N. Racing top fuel
W.I.N. Racing top fuel Joined: Dec 2006 Posts: 2,110 Byron, NY	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

Re: How big can you bore a 1969 426 Hemi block?? [Re: W.I.N. Racing] #2639251 03/31/19 05:58 PM 03/31/19 05:58 PM
Joined: Feb 2005 Posts: 982 western pennsylvania b1dartsport super stock
b1dartsport super stock Joined: Feb 2005 Posts: 982 western pennsylvania	I have one that is .65. After sonic check it was .80 on the thrust side of 2 cylinders. Will need a resleeve

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