What are the cast # for a 318 X block and are they 2 block or 4 bolt mains? Are they any other differance than a standard small block by sight?

Thanks Brian

The one I had was a 4-bolt may have been converted. The main webs were thicker similar to the 340 TA blocks.

Leon

4104230-318 and there's a big "X" cast into the front of the block (Cylinder #2)

I think X-blocks only came in 2-bolt main but, could be wrong.

edit: Oh yeah, Leon......solid main webs and pan rails.

I had a 67 or 68 318 truck motor that had an X cast into the block. I can't remember if it was on the front driver's side , or side of the block. The 318 X truck motor was the only small block to come from the factory with a full radius on the crank journals rather than the grooved journals like a conventional stock crank. I do not know if the block was any better than a standard or later 318, and I do not remember it being any different than a "stock" or standard production block. Alas, the crank had a bad thrust surface and was trashed.

I also had an early direct connection / mopar performance aftermarket X block. It was WAY heavier than a stock block. Filled pan rails and lower bore area are key ID areas. If I remember correctly, there was also a boss on the front driver's side that could be tapped to facilitate dry sump oiling.

My X block isnt drilled for a dipstick tube but came with 2 bolt mains.

pic

Whay is the max size these things can be bore to? (I know you have to sonic check them be be 100%)
But what size (bore) where the designed for?

Thanks Brian

4.100-4.125 depending on sonic test

yea my x block had a x on the pass.(#2) side and no dip stick hole.....

yep..everyone has it

4 bolter

I dont have a picture right now but my X block has the X on the rear of the left bank and it is a 4 bolt block

Im no Xpert (ha ha) but its my understanding the 5-79 blocks were all 2 bolters with the part number they were sold under, and the old book shows three main cap part numbers, one for two bolt caps and two part numbers for the 4 bolt caps.

The old book also said the X block 2 bolt main caps were of better stock then std caps, maybe that accounts for the two bolt cap part number.

Dont know how the foundry people really did the casting info but two of my blocks show only what looks like 15 minutes apart.

This is a bone stock nos 2 bolt X bottom, they are a fun peice to work with.

Also x on back