2536030-318-1???

[tsteiner61]

This is a 1972 318. What does the -1 stand for? I thought it stood for number of cores used to cast the block, but wouldn't 1 core be impossible? I thought the minimum was 2. Any help greatly appreciated.

[Stoga]

I believe there are 8 cores, one for each cylinder as well as one or maybe 2 for the crank area, a -1 block is usually a very good block because only one core has been replaced. But, no matter what number is there, if you are going to do a large amount of boring, have the block sonic checked. Also, if you find a block with a high number, and the cores have shifted to the thrust side, that can work in your favor! It's good to know about the core numbers, but I've have never had a problem due to a high core number when overhauling an engine. The number is an indicator basically, and if you have 3 otherwise identical blocks there, use the one with the lowest number first. But check it closely regardless, there's no telling what abuse any used engine has gone through, and the number won't tell you that.

[tsteiner61]

Thanks. I appreciate the good info. To be sure the block I pick will be sonic tested. How much (approx.) should this cost?

[Thunderstruck]

No, no, no! This is a damn myth. the -1 means it came from mold 1, It has no bearing whatsoever on the number of "cores replaced". EVERY CORE GETS REPLACED ON EVER NEW CASTING. Think about it, how do you get the sand out of the hollow spots inside the block, after all that is the core. the -1 is an identifier so that if there is a problem with a casting they know which mold the core came out of and can track it back. Don't believe me, ask someone that works at a foundry.

Steve

[tsteiner61]

Well... Here's the quote from the 2000 High Performance Mopar Engines & Tech Special Edition that got this whole debate started in the first place. Can anyone make sense of it??? (p.42)
"All Chrysler blocks have a dash code, which indicates the amount of cores used to construct the core. A '-2' would be the perfect block casting. Higher numbers indicate the factory used more individual cylinder cores to piece a block together. Not good, because now the bores will be slightly out of alignment. Most hardcore racers prefer blocks not exceeding '-4' when the cylinder bores must be expanded beyond .030 inch."
So is this '-1' block I'm looking at good or a dog?
Personally, I think both stories sound good. But I'm still confused as hell.

[pishta]

I always heard the core number denoted the core revision, lower being better in the sense that the core was on its first "run". Later cores 5,6,7 etc were the 5th cores to be molded, some being slightly shifted due to production tolerances.I realize they use the sand cores once, but they are all molded from a master casting. More confusion?

[mopartodd]

tstiener61. Just rebuild it. I just finished tearing down a "69" 318 with 95,000 miles. It was a -11 !!!!! block. But it was a very strong 318. in other words, if the block checks good, use it. Good luck.