class is in

[willie]

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    

[jft69z]

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.

[MC1of80]

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. 😁

[willie]

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

[MC1of80]

Whatcha trying to do Willie? Kevin has a 90 454 from a truck, dually, with 90k that he thinking of letting go. 

[willie]

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

[willie]

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.

 

[MC1of80]

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. 

[Paul D Valle]

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

[jft69z]

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

[Paul D Valle]

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

[Paul D Valle]

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

[Paul D Valle]

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

[willie]

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.

[MC1of80]

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. 

[willie]

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

[MC1of80]

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. 

[Dtret]

Whatever it is , I’m under the assumption that it should be under the hood of my chevelle. 

[Searsman]

It’s definitely a keeper! 

[Paul D Valle]

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 

 

[420ponies]

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.

[MC1of80]

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

[willie]

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!!!!

[MC1of80]

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 

[willie]

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