How can you tell if a 512 block has a 4 bolt main The engine is in the car and the pad has been machined

Check above the oil filter.If there are two pre-drilled holes for an external oil cooler then it has 4-bolt mains.You may also see Hi Perf Pass above these holes if the block isn't that dirty.

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Dean Ciampi(Spring Hill,FL)
Autumn Gold 1970 LS6 Chevelle
Team Chevelle Gold #52 Aces #3094

Dean what size are the holes suppose to be The middle one has a fiting for the oil preasure sending unit on it and the first hole is tapped with no plug on it.

Rick,
I am not certain that you can tell without pulling the pan. I have seen mid 70's trucks with oil cooleres from the factory and they have been 2 bolt blocks.


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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

The front hole(toward the front of the engine) has a half inch pipe thread drilled into the oil gallery.Ifthis block is a twobolt the front hole would be 5/16.The second or middle hole is 3/4.the last hole is the same size 2 r 4 bolt.

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Dean Ciampi(Spring Hill,FL)
Autumn Gold 1970 LS6 Chevelle
Team Chevelle Gold #52 Aces #3094

Correct me if I am wrong but 512 blocks were used only up till 71.So its safe to go the oil cooler way.

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Dean Ciampi(Spring Hill,FL)
Autumn Gold 1970 LS6 Chevelle
Team Chevelle Gold #52 Aces #3094

Dean I was having someone go measure the holes does your theory still apply or should we pull the pan

This is a quote from the book How to Hot Rod Big Block Chevys byBill Fisher and Bob Waar (HP Books)

Page 4 paragraph 2 "Note: Hi-Perf cast into a block is not a 100% guarantee that the block has four bolt mains. A resonably positive method of identifying a block with four-bolt mains is as follows: check the threaded openings immediately above the oil filter mount. If there are two plugs--one 1/2-inch pipe and the other 3/4-inch pipe, the block probably has four-bolt mains. Of course, the only foolproof way to check for four-bolt main caps is to pull off the timing chain cover or oil pan and start counting the the main cap bolts."

I can give you some tips on removing the harmonic balancer if you like. You probably could use a timing chain anyway.

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Dale P.
Team Chevelle Member# 423
65 El Camino
72 Monte Carlo
"..you did you take the washer off, right?"
Whiners please point your browser to http://www.nader.org

Rick,
If its a 512 block I will put my money down that you can check the size of the holes and be 99.9% sure its either a 2 bolt of 4 bolt without pulling the pan.512 blocks were passenger car blocks used from 69-71 therefore you don't have to worry about mid 70s truck oil cooler provisions.True what Dale said about the Hi perf stamping it is not a fool proof way,but the oil cooler provisions is with a 512 block.Just check the size of the holes and let us know what you found.Hope you got a 4 bolt!Did you get a chance to look at the casting date?

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Dean Ciampi(Spring Hill,FL)
Autumn Gold 1970 LS6 Chevelle
Team Chevelle Gold #52 Aces #3094

Thanks Dale P Thanks but the owner of the car I don"t think will have us take the engine apart so we will try the measurement theory

Dean the casting date is K 17 9 and it is located on the opposite side of the stamping 351 at the top back of the block . Is this in line so far for a LS6 block?

Dean Sorry 512 is the number not 351 n

260's pretty much right about this case, if there's two big pipe plugs it's more than likely a four-bolt.
Dated November 17th, it would be an early LS6, that's for sure.
Is the rest of the LS6 stuff there???

Rick,
Yes with that date I would put all my pennys that you got an LS6 block,that is ofcourse if the measurements are correct.Are you looking at an LS6 Chevelle?

Dave We Managed to take a valve cover off and the head is stamped 291 and has the smaller spark plugs. The intake is aluminim lowrise TSC all gone Headers M22 build sheet cowl tag 04 70 Atlanta Cowl hood CRV rear end 6500 redline tach

Well it also could be a 427.Chevrolet was casting 427s late in november 69.

260 Yes we are looking at an LS6 Chevelle But we are talking to the Father of the owner who can not be reached

260 If I remember correctly the casting date would be on the side of the block if indeed it is a 427

Rick,
sounds like the real deal.The casting date is a bit early for an april built car but I have seen stranger things.GM was on strike that year.Who knows?I would like to hear more about this car being an LS6 owner myself.Good Luck!

That may be true for earlier 427 blocks like the 439 block,but the 512 blocks had the date cast opposite of the casting number.

260, The car is locked up at a garage and i won"t be able to get at it till tomorrow. I already bought the car Triple black white stripes. My knees buckled when I first saw the car and if the motor is correct Which I think it is thanks to all the info supplied by you guys we have a winner

Some engines also had vin. numbers stamped on the transmission flange above the oil filter.

Oh *****. Does it go FAST?

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Dale P.
Team Chevelle Member# 423
65 El Camino
72 Monte Carlo
"..you did you take the washer off, right?"
Whiners please point your browser to http://www.nader.org

Sounds pretty good. Just for info sake, the 512 block came with 2 bolt mains in the ls-5 versions in Montecarlos and full size cars. http://www.chevelles.com/forum/smile.gif http://www.chevelles.com/forum/smile.gif

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Mr. D
72 454 El Camino
68 RS/SS Camaro
73 RS/LT/Z28 Camaro
99 Firebird TA WS-6 A4

260 Today we measured the hole next to the oil sending unit its bigger than 5/16 its around 7/16 but the tapped hole where the sending unit is a lot bigger don:t know exact size but a fitting goes in the block and the sending unit fits on to that. The only thing that threw me off is that it said Malibu on the door panels.,

Here we go again with the SS vs Malibu door panel debate.... http://www.chevelles.com/forum/smile.gif
The verdict is, some earlier 454 cars said Malibu on them because of a shortage of SS door panel emblems. My LS6 was built 02-20 at Atlanta, and had Malibu door panel emblems.
Is the build sheet you have glued to the back of one of the front door panels, or another sheet??? Does the car have the original door panels on it??

Rick,
Sounds like you got a LS6 there.As Dave said both Malibu and SS door panel emblems were used.I have heard a lot of LS6 cars came out of Atlanta with the malibu emblems.Mine was built in Baltimore and I have the SS emblems.

Dave, The door panels are in great shape so they could have been replaced but I have the original build sheet that was glued to the inside door panel(build sheet still has cardboard glued to it) car was built 04-23 at Lakewood And no B22 option on the build sheet. Original selling dealer was Central Chevorlet Inc 2930 Peachtree Atlanta GA

Sounds like a great find. So.....how much are you paying???

Car sounds like a clone of mine, except I've got the convertible (triple black w/white stripes) Good luck with the car! BTW, mines got malibu door panels as well (Nov 1969 build)

[This message has been edited by Black LS-6 (edited 11-02-99).]

Rick- Good find! The build sheet is glued to the back of the old door panel. Someone must have put new ones in. Every Atlanta car I've seen has one on the back of a door panel. Your car should have the two fuel line setup with the long pump??? On the build sheet, box number 33, what are the three numbers there??
Also, is it missing the rest of the smog stuff??

Dave, All the smog is gone except tube to air cleaner from valve cover and the PCV line.It does have the return line for the fuel and the long fuel pump.Box33 of the build sheet has number 768.