Agreed & I think the first number went from a (3) to a (4).

According to race bulletin #8, July 1982:

"The early 360 ('71-'76) blocks are a special case. They use a 4.00" bore (340 was 4.04") but the block was made with the 340 water-jacket core. This means that these blocks can be bored to the same actual bore size as any 340 and have the same borewall thickness. This is NOT true of the newer 360's"

...
Actually 0.200" is what's considered minimum for a major thrust in the rest of the old stuff. For Mopar engines if you can get 0.170" on a major thrust it's going to work. And the non-thrust parts of the block can go all the way to 0.120" and some won't even make that, and I mean virgin blocks! If you have 0.170" or more on all thrusts you go out and buy lottery tickets!

As for the thousands of 600hp 360s out there, I think they're all out racing those fabled 383 Hemis that Gramps had in his Road Runner. Put another way I don't believe it. If there are 100 360s making 600hp I'd be surprised.

mine was cast 10/10/73.. 496 block. What do you mean 3 to a 4?

Well my count is up to three 600+ hp 360s.

Well my count is up to three 600+ hp 360s.

Blazin' Bob, any new casting gets a new casting number. Even if it is a little tiny change. Or maybe the mold cores are starting to flake.

The only time a significant casting change was made without a casting number change was the last half of the run of 451 heads for bigblocks. Engineering corrected some thin areas to make them safer to port but because the bigblocks were already planned to be out of production they didn't dare give it a new casting number. So they instead put the number "1" on the end of the head.

Casting numbers increase with time as more and more castings are designed. So for example a casting number with a 1 in front is probably from the '50s, 2 would be '60s, 3 would be late '60s, etc. I think the casting numbers are in the 5s nowadays.


In the early '80s you could buy a bare 452 casting for something like $59.00.

R.

And? Point being it can be done and those blocks live no problem.
Dude came down to sonic my 496 block. 24pts every cylinder all .2+.
$100 well spent.

I had a 318 block sonic tested and when it spilt 3 bores I measured the busted parts and none of them were what he told me, not even close so watch it done if possible and listen to what p body said, a chain is only as strong as it's weakest link or in other words a cylinder is only as strong as it's thinnest point.

I use to have a guy doing my sonic checking that
did 64 reading per cyl... charged $75 at that time..
he was well worth it... he was a old hard core guy
that did a lot of machine work also... very nice guy
and his prices on everything was on the cheap side compared
to most shops... I watched him do my mega block so I
knew he wasnt BSing on the numbers... guys that get a
small hand full of readings have no idea what the block
is really like... a 1/2" away it could be paper thin..
plus if he found a area that was iffy he would do a dozen
readings just in that area... no charge

What's my point?

You said, "Plenty of LA blocks running 600+ and living a long happy life."

I have now counted three. That's not plenty.

My point is it's super easy to SAY you have a 600hp 360. If you had said there are plenty of claimed 600hp 360s, I would have had to agree.

Way back in the days of smallblock Pro Stock the Mopar guys started having trouble with 2-bolt 340s at around 600hp. They reportedly scrapped T/A or AAR cars for the blocks which had provisions for adding four bolt main caps.

Or maybe that's just a myth.

R.

Nice article..but did I miss the ET slips?