Strange 318 Block

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Not a warranty block, it has numbers stamped in both places, I read "AC202" on the vin stamp and "OM318 04289587" on the driver side under the head.
View attachment 1715319370 View attachment 1715319371

Little bit of Decoding here:

OM318 04289587

O = 8-78 (date, built August 1978,) wonder if the cast number is a 78 instead of 79 ?
M = Built at Mound Road Plant
318 = Self Explanitory
04289587 = Have not figured this number out yet.
 
Little bit of Decoding here:

OM318 04289587

O = 8-78 (date, built August 1978,) wonder if the cast number is a 78 instead of 79 ?
M = Built at Mound Road Plant
318 = Self Explanitory
04289587 = Have not figured this number out yet.

Thanks!! I believe its a 79, it came out of an 1980 Volare Roadrunner, but it could possibly be 78, its incredibly hard to read the last number, same as the 04289587, i could be off by a number.
 
Thanks!! I believe its a 79, it came out of an 1980 Volare Roadrunner, but it could possibly be 78, its incredibly hard to read the last number, same as the 04289587, i could be off by a number.

Yes those are hard to read at times.

The front stamping says 8-78 for the build,
if 78 MyMopar.com says 59-78:
4104230 318 - LA Race - Painted Orange,
and your's definatley painted mopar blue.
 
Also to the poster who mentioned something about possibly thicker cylinder sleeves, heres a picture through the freeze plug on the side if that helps, they do look close, but I don't have another block to compare it to.
IMG_20190413_202733.jpg
IMG_20190413_202741.jpg


IMG_20190413_202025.jpg
 
Also to the poster who mentioned something about possibly thicker cylinder sleeves, heres a picture through the freeze plug on the side if that helps, they do look close, but I don't have another block to compare it to.
View attachment 1715319457 View attachment 1715319462

View attachment 1715319452

That's a good observation, stick a feeler gauge in there and check the gap between the 2 cylinders after cleaning it off a bit, .100" ths or so ?

Looking pretty stock to me, but another member may have an open stock block he could measure for you so you can compare. Then you can put your mind at ease to what it is.

That R on the Block, will keep an eye open if I find out what that means in the future can let you know.

Nice stock block you have there all things considered.
 
Well, based on all the replies, nothing interesting here, this block is heading back out to the scrap pile from where it came lol

I appreciate all the responses :thumbsup:
 
Whoa ! I love the stock bore 318s, hate to see you throw that one out especially with just about zero ridge. We know how to tweek them up and get them to perform nicely with basic parts and some good port matching. My buddy Brian is getting at least 300 hp out of his 69 318 built engine. We want to get it on the Dyno this Summer the way it is performing right now I bet it is over 300. Kind of all about the flow and velocity going through those engines and bumping up the compression a tad. Pretty surprising what the 318s will do, tough engines too.

See you are in Manitoba Canada, anywhere near Winnipeg? I am just South of the Twin Cities in Minnesota.
 
Please dont scrap it give it or sale it to someone who will use it!
If I wasn't sk far away I'd take it i need a good 318 block.
 
Whoa ! I love the stock bore 318s, hate to see you throw that one out especially with just about zero ridge. We know how to tweek them up and get them to perform nicely with basic parts and some good port matching. My buddy Brian is getting at least 300 hp out of his 69 318 built engine. We want to get it on the Dyno this Summer the way it is performing right now I bet it is over 300. Kind of all about the flow and velocity going through those engines and bumping up the compression a tad. Pretty surprising what the 318s will do, tough engines too.

See you are in Manitoba Canada, anywhere near Winnipeg? I am just South of the Twin Cities in Minnesota.

I'm a big fan of the magnum I'm running now, I bought it running for $500 3 years ago and I've been beating on it every day since, this block needs probably at least $500 of machine work so that's why I wouldn't really give it a second look compared to just going out and getting another running magnum for $500, they're cheap and plentiful and have lots going for them, compared to this rusty block lol
 
Yeah don't scrap it ya big dork. lol It's a good foundation for somebody.
 
Bring the 318 Block down to Minnesota to Mopars In the Park this early Summmer, just on the East side of the Twin Cities, not that far away for you. Then you can come and enjoy the show and swap meet. I will buy you lunch and take the block off your hands and see it gets to a good home.
 
Yes it is a race engine.
How about the cast lines left on the main webs. Opposing main web faces .

Notice the Mark's where it looks like the ones of misplaced core/freeze plug holes.

This 318 cast 12-23-71 block has the same outlines or 'ghost' core plug imprints. But ththe main webs are machined flat. It's not a race block though...but it bored 4.040

IMAG2574.jpg
 
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I'm a big fan of the magnum I'm running now, I bought it running for $500 3 years ago and I've been beating on it every day since, this block needs probably at least $500 of machine work so that's why I wouldn't really give it a second look compared to just going out and getting another running magnum for $500, they're cheap and plentiful and have lots going for them, compared to this rusty block lol
You been talking to @j par ain't you? Lol
 
and ''R'' blocks also .

JimJimJimmmy what do you know about the "R" blocks ? That is what this whole post is about, we all have been trying to identify them.
Any chance they are a stock block that have been cast with a high nickel content?
 
How about the cast lines left on the main webs. Opposing main web faces .

Notice the Mark's where it looks like the ones of misplaced core/freeze plug holes.

This 318 cast 12-23-71 block has the same outlines or 'ghost' core plug imprints. But ththe main webs are machined flat. It's not a race block though...but it bored 4.040

View attachment 1715319526

And it's a completely different casting number. Yet another piece to the puzzle.
 
JimJimJimmmy what do you know about the "R" blocks ? That is what this whole post is about, we all have been trying to identify them.
Any chance they are a stock block that have been cast with a high nickel content?


You are beating the high nickel thing to death. ALL Chrysler blocks had more nickel than the ford or Chevy. If you've ever machined or honed them you can tell the difference with a blind fold on.

The high nickel thing is a GM deal. Today, nickel content is almost meaningless. Compacted Graphite is where it's at.

The OP has a run of the mill 318. Nothing wrong with it. The unfilled pan rail gives it away. I didn't need to see anything but that.

I've personally never seen an R block that didn't have the lifter banks cast for 48 degree lifter bores so that ruled out the R block theory at the first picture.

BTW, the X block wasn't released until 1979. Until then, the T/A block was the over the counter race block. It was superseded by the X block which was superseded by the R block in the mid 1990's IIRC.
 
JimJimJimmmy what do you know about the "R" blocks ? That is what this whole post is about, we all have been trying to identify them.
Any chance they are a stock block that have been cast with a high nickel content?

I think there's some confusion. I think people are confusing the R block thinking of the R3 block. The R3 IS a race block. The one in this thread is not.
 
I think there's some confusion. I think people are confusing the R block thinking of the R3 block. The R3 IS a race block. The one in this thread is not.


No, there are R blocks not denoted with a number. If it's a true R block it will have a filled pan rail which is easy to spot, and the lifter bank will be cast with provisions for 48 degree lifter bores.
 
No, there are R blocks not denoted with a number. If it's a true R block it will have a filled pan rail which is easy to spot, and the lifter bank will be cast with provisions for 48 degree lifter bores.

It does not. He posted pictures on the first page.
 
I have been looking around and there's a lot of speculation of this casting number. I am changing my opinion. It's a early 80's 318 block from what I have read. I corrected my parts book.
 
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