Strange 318 Block

[George Jets]

This is a main cap out of it, could the HN mean high nickel? Or am I grasping at straws here lolView attachment 1715319357

I like your thinking on the rod cap, HN high nickel . . . funny have to look into that one some more always like to be optimistic until proven wrong. Lol . .

Let's go back to the VIN stamping area on the R Block, is it blank or is there a VIN number on it ?
If it is blank then it is a real good chance it is a low mile warranty block.

My 76 360 warranty block VIN stamp is Blank, and it also has an "S" stamped into the flat upper left stamping area by the front of the driver's side head. The S code at mymopar.com transfers to identify a warranty block. So check both of these areas and get back to us.

Thanks

 

[toolmanmike]

That is NOT a race block, it's a common, run of the mill 79 318 block. The x blocks had the same casting numbers making it confusing, but there is nothing special about the block pictured

Not according to my book. We can only be as accurate as the information we can uncover.

 

[replicaracer43]

Not according to my book. We can only be as accurate as the information we can uncover.

Respectfully, you are wrong. That casting number was used on the X blocks AND the regular production blocks. That is NOT, in any way, shape or form, a race block.

 

[RustyRatRod]

Not according to my book. We can only be as accurate as the information we can uncover.

The reason for that is because the casting number on the race block is the same as the one here. The exception is that it has a big X cas into the front and has four bolt caps, where this one does not.

 

[toolmanmike]

The reason for that is because the casting number on the race block is the same as the one here. The exception is that it has a big X cas into the front and has four bolt caps, where this one does not.

And my book only goes to 74 and this block is the next to the last entry. I don't see any other small blocks by that number though.

 

[George Jets]

Where exactly would I be checking for that?

The VIN stamping area is the small 1/2 inch tall x 4 inch wide flat machined off area on the lower right front of the block at the oil pan line below cylinder # 2.

And check the upper front left flat machined area just below the front of the left head, and see if there is an "S" stamped in there . . or whatever other alphabet letter you can find and we will reference it back to MyMopar.com

 

[George Jets]

Good discussion here. RustyRatRod is making sense with the 4 bolt main and X theory. Would like to see what our man comes up with for the stamping identification areas yet, an see if the Rod Cap HN stamp means anything at all other than a part number.

 

[Tooljunkie]

Interesting. I have 2. One came from an early 80’s dodge van.
Other was a customized engine with a poly crank in it. I found this somewhere..

 

[mchartier105]

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.

 

[mchartier105]

Good discussion here. RustyRatRod is making sense with the 4 bolt main and X theory. Would like to see what our man comes up with for the stamping identification areas yet, an see if the Rod Cap HN stamp means anything at all other than a part number.

As another member pointed out, I'm holding the cap upside down, it should be NH.

 

[replicaracer43]

Guys, the reason the casting number is the same, is when they developed the Xblock for racing, they modified the already in use core boxes, and didn't bother to change the numbers. The blocks were rough bored to 318 bore size, and had filled in pan rails, thicker decks and wall thicknesses. And a big freaking "X" right up by the dipstick area. The engine in this discussion is a plain old 318, nothing special AT ALL

 

[mchartier105]

Guys, the reason the casting number is the same, is when they developed the Xblock for racing, they modified the already in use core boxes, and didn't bother to change the numbers. The blocks were rough bored to 318 bore size, and had filled in pan rails, thicker decks and wall thicknesses. And a big freaking "X" right up by the dipstick area. The engine in this discussion is a plain old 318, nothing special AT ALL

Not saying I have something special, but all of the other blocks I've seen online with that number dont have the R cast in them.

 

[Rocket]

The racing version of that casting number, the X-block had distinguishing features like the X cast in the block, the front cover area has more meat diagonally across and there is more meat in the main web casting. These are the areas you should check on the 318 block you have. I do not see the thicker main web indicating it is a stock 318 block in my opinion. See aftermarket X-block pictures below.

 

[George Jets]

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

OK, good pictures.

Ran across one article that R meant runs on regular gas and, P means it runs on premium, I believe this was in the ID stamping areas and not the Block Cast in Casting Number though.

Need some time to think yet.

Can maybe do a grinder test on a standard block and the R Block and see which one sparks more. Regular Cast iron is supposed to have a real short spark trail.

Also can maybe come up with some type of hardness test on the rough cast areas of the outside cast areas of the block, simple sharp ground screw driver tip . . see if it diggs in easier on either of the blocks you might have around. Or some other test you might come up with.

Seem kind of odd that the only engine that comes up on the StockMopar.com chart for the Race Engine is that 318 Cast number you have. Probably some well experienced members that know what up with it for sure.

Fun looking into it.

 

[George Jets]

The racing version of that casting number, the X-block had distinguishing features like the X cast in the block, the front cover area has more meat diagonally across and there is more meat in the main web casting. These are the areas you should check on the 318 block you have. I do not see the thicker main web indicating it is a stock 318 block in my opinion. See aftermarket X-block pictures below.

View attachment 1715319380 View attachment 1715319381 View attachment 1715319382 View attachment 1715319383 View attachment 1715319384 View attachment 1715319385

Yeah that X Block definitely looks stronger on the webs to the mains, filled to the top and machined flat.

 

[Heywodja]

I used to get motors like these from Rod Hall racing In Sparks NV back in the day. They were different than regular 318 blocks, they had thicker cylinder walls. you might want to double check the sleeves, the ones I was getting could be bored out to 4.04 or greater. They also worked with a lot of aar and nascar stuff, also remember the T/A's and AAR had those cubic inch restrictions on them in race trim so the AAR and T/A were actually 303.8 CI.

Petty Enterprises used to get a lot of limited production or race only stuff that seemed to find its way into the Hall's racing shop..

 

[Rocket]

The X-Block used a production casting number and other markings to allow the block to be used in certain classes of racing that required a stock or stock type block. I believe this is the reason the casting number and year of casting is the same as the block you have.

 

[mchartier105]

OK, good pictures.

Ran across one article that R meant runs on regular gas and, P means it runs on premium, I believe this was in the ID stamping areas and not the Block Cast in Casting Number though.

Need some time to think yet.

Can maybe do a grinder test on a standard block and the R Block and see which one sparks more. Regular Cast iron is supposed to have a real short spark trail.

Also can maybe come up with some type of hardness test on the rough cast areas of the outside cast areas of the block, simple sharp ground screw driver tip . . see if it diggs in easier on either of the blocks you might have around. Or some other test you might come up with.

Seem kind of odd that the only engine that comes up on the StockMopar.com chart for the Race Engine is that 318 Cast number you have. Probably some well experienced members that know what up with it for sure.

Fun looking into it.

I read that too somewhere, but yea I don't think it was with the casting numbers, I've yet to see any other block with this R cast on it, if anybody who has one could post a picture of it that would be great, and the hardness test would be tough, as the only other block I have is a slant 6 block that's been sitting outside for the last 4 years lol I absolutely don't have an X block, that block looks STRONG compared to the one I have sitting here, the only thing I think it could possibly be at this point is just a higher nickel content block, if anything.

 

[George Jets]

Guys, the reason the casting number is the same, is when they developed the Xblock for racing, they modified the already in use core boxes, and didn't bother to change the numbers. The blocks were rough bored to 318 bore size, and had filled in pan rails, thicker decks and wall thicknesses. And a big freaking "X" right up by the dipstick area. The engine in this discussion is a plain old 318, nothing special AT ALL

Making Sense

 

[dartfreak75]

I think in this case, that is some sort of warranty block and the R means replacement. All the race blocks I am aware of had 4 bolt main caps. The X would indicate a race block. There is no X.

That makes sence but why would they have a special casting just for warranty replacements?? Seems like that would be alot more expensive than just getting a regular casting from the manufacturer?

 

[George Jets]

This is interesting to look at.
Look at the lower cylinder skirt area on the X Block compared to the R Block.

X Block is way, way, way stronger in that area . . filled in solid internally from the lower cylinder bore right up to the oil pan bolts. R block looks light duty compared to this.

 

[RustyRatRod]

That makes sence but why would they have a special casting just for warranty replacements?? Seems like that would be alot more expensive than just getting a regular casting from the manufacturer?

He's found that it has a VIN which tells us two things. It's not a warranty block and it's a stone stock 318 block just like any other.

 

[dartfreak75]

He's found that it has a VIN which tells us two things. It's not a warranty block and it's a stone stock 318 block just like any other.

Yea I saw that after i replied lol.

 

[mchartier105]

He's found that it has a VIN which tells us two things. It's not a warranty block and it's a stone stock 318 block just like any other.

I'm thinking that too, but again, I'm curious, what's with the R? It would have made total sense to me if it was a replacement block. But now I'm just confused again

 

[RustyRatRod]

I'm thinking that too, but again, I'm curious, what's with the R? It would have made total sense to me if it was a replacement block. But now I'm just confused again

It's not race.

It's not like it's a piece of ****. It's a good standard production 318 block. Still better than any standard production chevy block.