willie Posted November 18, 2023 Share Posted November 18, 2023 i have a '68 454 4bolt main block only, that has been sitting for awhile. I have been kicking it around to have it built. What i need is to find out if it has been bored out?? The reg bore would be 4"? correct? I am getting 4.29 or 109mm. Is this 30 over? What would be 60 over? 4.60 or 117mm? It has to be honed or bored one more time to get the surface rust off, what would my best option? Tkx in advance Willie Quote Link to comment Share on other sites More sharing options...
jft69z Posted November 18, 2023 Share Posted November 18, 2023 A standard bore diameter for a 454 would be 4.250" a .030" overbore would result in a cylinder diameter of 4.280" a .060" overbore would result in a cylinder diameter of 4.310" If you're measuring 4.290, then that is .040" larger than a stock cylinder dimension. As far as cleaning up the surface rust, it all depends on how deep it is. If you're already at .040" oversize, depending on who you ask, there's not too many overbores left in that engine, though most feel a .060" bore is just fine. If you hone it out to clean up the rust and remove a lot of material, that will possibly increase the piston to wall clearance beyond acceptable limits. 4 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted November 18, 2023 Share Posted November 18, 2023 Sorry Willie, the 454 didn't come out till 1970. Could be a 68 427 block. A 427 is basically a 454 (now) block and a 396 crank. Chevy stroked the crank to 4.0 to make the 454 with the 427 block in 70. Also, can you read the code off of the pad? It will tell you exactly what it's from and size. .060 overbore is max I would go without checking cylinder wall thickness. Since you have a bare block only I suggest the .060 overbore and a 4.250 stroke crank for a 496. Purchase a rotating assy. You will never regret it. 😁 5 Quote Link to comment Share on other sites More sharing options...
willie Posted November 18, 2023 Author Share Posted November 18, 2023 Joe Thanks for the info and I am getting a better gauge and recheck tomm. Tom Thanks I am not sure if i can read the pad but i will check tomm also. I think i got the build date from the back above the oil canister. Yes i would not go over .060 over. I will check tomm to make sure of what it is as i am undecided whether to build this or rebuild a different one that i have. Thanks for the help guys 2 1 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted November 19, 2023 Share Posted November 19, 2023 Whatcha trying to do Willie? Kevin has a 90 454 from a truck, dually, with 90k that he thinking of letting go. 1 Quote Link to comment Share on other sites More sharing options...
willie Posted November 19, 2023 Author Share Posted November 19, 2023 Hey Tom, the truth is i was trying to make a little room. I bought this block many years ago at Carlisle but its going to cost about the same+- to build another that i have or even buy a crate. I don't really want to buy a crate/used with 4 BB just sitting "in stock". I was trying to figure out if i should build this bare block or sell it to get it out of the way, make some room. Would of been a lot easier if it was already bored to .060 over. lol But Tkx Tom and Kevin 1 Quote Link to comment Share on other sites More sharing options...
willie Posted November 20, 2023 Author Share Posted November 20, 2023 The cast block number is 3963512. I checked as Tom suggested the pad and i cant read anything because it has been decked already. I also checked the build date on the back as i read it as 6 67 Not correct, its upside down. It actually is L9 9 and that according to the book is December 9th day of 1969. I also checked the bore with a better gauge, all cyl are about 4.2825-4.2915 this translates to .040 over, so it has 1 more bore left, I have been told. According to the book it could be one of these 427ci, 335hp,390hp,400hp,425copo hp,430hp,or 435hp with 4 bolt mains. I am really not looking to sell it but i am throwing it out to the members, if anyone is interested here PM me. Thanks Again for the help Joe and Tom. 5 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted November 20, 2023 Share Posted November 20, 2023 Sounds like you have a grasp on what it is by the numbers you did find. A 512 block is a good block for a build. 1 Quote Link to comment Share on other sites More sharing options...
Paul D Valle Posted November 22, 2023 Share Posted November 22, 2023 If it's a 4 bolt main block dated late 69 then it is a valuable 1970 LS6 BLOCK. Chris White, who restores '70 LS6 cars may want to purchase it. Good Luck 1 Quote Link to comment Share on other sites More sharing options...
jft69z Posted November 22, 2023 Share Posted November 22, 2023 1 hour ago, Paul D Valle said: If it's a 4 bolt main block dated late 69 then it is a valuable 1970 LS6 BLOCK. Chris White, who restores '70 LS6 cars may want to purchase it. Good Luck According to this snip from a 'Chevelles.net' list, that casting number had the possibility to be in some really cool cars (427 and 454). Based on the December date though, it's likely to be a 454, but not guaranteed to be a LS6. 3963512 427 68-69 Passenger 385,425 HP 3963512 427 69 Chevelle,Camaro COPO (Central Office Production Order) 3963512 427 69 Corvette Late 69 3963512 454 70 Corvette,Passenger 360,390 HP 3963512 454 70 Chevelle LS-6 450 HP 3963512 454 70-71 Pass,Chevelle, Monte Carlo 3963512 454 71 Corvette 365,425 HP Quote Link to comment Share on other sites More sharing options...
Paul D Valle Posted November 22, 2023 Share Posted November 22, 2023 3 minutes ago, jft69z said: According to this snip from a 'Chevelles.net' list, that casting number had the possibility to be in some really cool cars (427 and 454). Based on the December date though, it's likely to be a 454, but not guaranteed to be a LS6. 3963512 427 68-69 Passenger 385,425 HP 3963512 427 69 Chevelle,Camaro COPO (Central Office Production Order) 3963512 427 69 Corvette Late 69 3963512 454 70 Corvette,Passenger 360,390 HP 3963512 454 70 Chevelle LS-6 450 HP 3963512 454 70-71 Pass,Chevelle, Monte Carlo 3963512 454 71 Corvette 365,425 HP If its has factory 4 bolt mains its an LS6 block because late tonawanda engines were made for the 1970 model year. Thats when then discontinued the 375 hp 396/402 Quote Link to comment Share on other sites More sharing options...
Paul D Valle Posted November 22, 2023 Share Posted November 22, 2023 Just now, Paul D Valle said: If its has factory 4 bolt mains its an LS6 block because late tonawanda engines were made for the 1970 model year. Thats when then discontinued the 375 hp 396/402 LS 5 blocks were all 2 bolt mains 1 Quote Link to comment Share on other sites More sharing options...
Paul D Valle Posted November 22, 2023 Share Posted November 22, 2023 25 minutes ago, Paul D Valle said: LS 5 blocks were all 2 bolt mains I think another members comments are correct. If it's a 1968 , 512 block then it was a 427 engine before being bored Quote Link to comment Share on other sites More sharing options...
willie Posted November 22, 2023 Author Share Posted November 22, 2023 Good conversation guys and i am also learning from this. All i can say about it is i bought it from someone in Carlisle many years ago and he told me it was an LS6. The block has been decked so i cant read anything off the stamp pad. The block is a 512 block. The date stamp is L 9 9 December 9th of 69. and it has 4 bolt mains. I wish i could tell you more but i have this block at least 13-15 years. I would think it is a LS6 because it also has the enlarged hole by the oil filter. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted November 22, 2023 Share Posted November 22, 2023 Willie, the 425hp 427 also has the large oil passage by the oil filter and would have the same bore as a 454 and 4 bolt mains BUT the casting date suggests it is probably an LS-6 block. 1 Quote Link to comment Share on other sites More sharing options...
willie Posted November 22, 2023 Author Share Posted November 22, 2023 Thanks Tom, I am not saying it is, or it isnt, just saying what i was told and what i know to be true. I really don't know, but i kind of like learning about this first hand 1 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted November 22, 2023 Share Posted November 22, 2023 4 minutes ago, willie said: Thanks Tom, I am not saying it is, or it isnt, just saying what i was told and what i know to be true. I really don't know, but i kind of like learning about this first hand Also just learned it could be from a 360 or 390hp 454 70 Vette. Quote Link to comment Share on other sites More sharing options...
Dtret Posted November 22, 2023 Share Posted November 22, 2023 Whatever it is , I’m under the assumption that it should be under the hood of my chevelle. 1 1 Quote Link to comment Share on other sites More sharing options...
Searsman Posted November 23, 2023 Share Posted November 23, 2023 It’s definitely a keeper! Quote Link to comment Share on other sites More sharing options...
Paul D Valle Posted November 23, 2023 Share Posted November 23, 2023 Someone with a documented LS6 car without the correct motor would love to buy it to complete his car. As stated before, if it has factory 4 bolt main caps it definitely is a LS6 based on the late 69 date code. 360/390 hp Corvettes were LS 5 which have 2 bolt mains. If you would like to verify what it is you can reach out to Chris White in New York or engine builder known as big block Bruce who is an expert on this topic. Otherwise you only have hobbiest opinions to go by. Best Quote Link to comment Share on other sites More sharing options...
420ponies Posted November 23, 2023 Share Posted November 23, 2023 A .060" over bore block is going to need some serious cooling capacity. 4 row with good draw fan at the least. I'll be on the fence with my 3 row and .030"over 454 4bolt block with 396 forged crankshaft. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted November 23, 2023 Share Posted November 23, 2023 Big Red has a 496,.060 454 block, original 4 core radiator,7 blade fan with HD clutch and has no issues at all. Ask anyone that was at Carlisle this year. I drove it in traffic, highway, to town to eat, sat idling for a while and no issues.... Thank goodness. Lol 2 Quote Link to comment Share on other sites More sharing options...
willie Posted December 5, 2023 Author Share Posted December 5, 2023 Update on this block. I brought it to another machine shop, he said it most likely has another bore left in her. But there are 3 heili coils that he doesn't like but he could fix them. But the reason he said not to waste my money on it, is because one of the heads has some deep rust on it and he said he would have to take way to much off of it to get the rust craters out. So bottom line is, she is a paper weight!! Thanks Everyone for all your help!!!! 1 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted December 5, 2023 Share Posted December 5, 2023 55 minutes ago, willie said: Update on this block. I brought it to another machine shop, he said it most likely has another bore left in her. But there are 3 heili coils that he doesn't like but he could fix them. But the reason he said not to waste my money on it, is because one of the heads has some deep rust on it and he said he would have to take way to much off of it to get the rust craters out. So bottom line is, she is a paper weight!! Thanks Everyone for all your help!!!! One of the heads or the deck of the block where the head gets bolted onto is too rusted Willie? Obviously you know if it's the head, use different heads. But if the block, I agree with the rebuilder. But then again, nothing is impossible. But is it worth it? We still have the 90 454 in stock. Lolol 1 Quote Link to comment Share on other sites More sharing options...
willie Posted December 5, 2023 Author Share Posted December 5, 2023 Yes Tom its the top part where the head sits on the block, not the head itself. He said if it was a number matching engine to the car he would do it. But because its not, he suggests not to bother, just use one of the others. Tkx for the offer Tom, but now i have to rethink my plans. Good thing is i can move around the car a little better now!!! lol 1 Quote Link to comment Share on other sites More sharing options...
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