1968 SR block question D100
 

It’s a SR block date code D100 but the block only has two mount holes on each side. All the other SR blocks cast in 70 or 71 I have seen have all five mount holes.

maybe a strike era block

What is the block number? Looks like a 68 block. Perhaps the date code is incorrect?

It's a 68 SR 4 bolt I had a 69 ram air IV SR block cast in 71 that had all 5 mount holes.

What does the 85650 stand for on a SR block

Interesting. What is the casting number? Is the number as cast or ground and re stamped?

Not sure anyone knows for sure. SR likely stands for "Service Replacement"....the leading digit "8" might decode 8 cylinder engine....the last 4 digits are a mystery it seems...

The digits after SR are a sequence. For instance, this block is SR85650. The next SR Block would be SR85651... Is the block for sale?

No it’s not for sale it’s my next build. The block is ground 2506 but looks double stamped.

Here's an SR block that is in a 68 GTO Convertible. Later casting date number of September 23, 1971, smaller SR number, has the 5 engine mount holes, and drilled for 4-bolt mains with 2-bolt caps.

Did the SR numbers start over every year?

Double stamp

The 9792506 that is in the picture is a 1968 Ram air I or Ram air II service replacement block that was manufactured on April 10 1970

Actually, with a 1970 cast date, it's probably a 1969 Ram Air IV Service Replacement
 

Although the casting/stamping number is the same for 1968 RAI, 1968 RAII and 1969 RAIV.

And, being cast in 1970, it was most likely originally a 9799914 400 2-bolt main block.

The double-stamping (with 2 different font sizes) is peculiar. I've handled about a dozen ground-and-stamped SR blocks, of various vintages from 1967 to 1973 and all had the LARGE font stampings.

I've never seen one re-stamped with the little font size. Who knows.

That pad looks machined, not cleared with a hot knife or ground.

What are the casting numbers on the caps?

With only 2 motor mount holes per side and the large "68" by the distributor hole... wouldn't this indicate the block started as a 9790071 casting?



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You're right, it's probably a 9790071 casting
 

I'd guess that there is not the 'O/O' casting in the lifter valley, which a 9799914 block would have.

Boss, I thought the same thing about the ground area - it somehow looks wrong. But I was kind of concentrating on the font size of the stamped digits.

Maybe it was a new guy working on the casting/foundry line?

Also just noticed the chrome plated hex steel block drain plug in the 2nd photo at the beginning of this thread. Now would be a good time to ditch those and go to a brass plug. Last set of the chrome plugs I came across we ended up having to carefully drill them out and extract them piece by piece. They rust very securely to the block threads after a year or two.

It has no OO in lifter valley.

Just got another 400 SR block SR811992 D201 that’s 6342 higher than the other one cast 1 year earlier D100 not sure it means anything but just over 6000 service blocks would seem about right in a year. I’m wondering if the engine size was a factor in the numbers on block?

Maybe Rocky will see this thread?
He has some interest in these blocks.



:)