I've read rumors both ways on 413 cold weather that they a 440 under bored to they a normal block, really know I need to sonic check to be sure but figured maybe someone could give alittle insight befor hand, block he no casting numbers on sides and in bell I think it was 8R

Sent you an email.

Could be. Looks like a 1972 casting and it has the late model ribs on the block so it might be a 440 core that was left undersize on the bore. Sonic check will tell you for sure.

I have one like that which we bored to a 440 but a couple of cylinders were a little thin at 4.320 final bore size. So I'm not sure that they used the same exact core box as a 440 block. Only way to know for sure would be to get some factory documentation. My guess is that they had separate 413 cores.

Thanks for the info I'm working all the numbers on a ci restricted class of 410ci so wouldnt need push it much over 383 size

Does it have the unmachined water pump bosses on the back of the block also?
If so it is a industrial 413 block

If I'm not mistaken the motor came out of a bus, guess it was a pointless question in long run cause I know a sonic check will be in store

The industrial 413 motors where used in many different applications like busses, trucks, class A motor homes, marine(including reverse rotation for dual power plant boats) and stationary power and water pump plants

Ya the fun part is going be fitting victors on top of it 👎🏻

Yeah if you are doing something like that then you need to sonic check it and figure out the best combo of ring size and stroke to hit your cubic inch limit. If it is a serious racing effort then ring size is probably the most important variable since rings can make or break a serious racing engine. There are a ton of rings available in the smaller bore size (Chevy size) but as you get up to the Mopar 440 size then the good rings are harder to find.

If it was me I'd cozy up by the fireplace with a ring catalog and find a good metric pack at 4.250 or 4.280 and then double check the sonic numbers and then order the crankshaft stroke to match.

You got mail 😂

I tested one of those '72 HD 413's and still have the data. What I can remember is that it seemed thicker but NOT to the point that it would be as thick as a normal 440 block when bored to 440 size. I still have one of those blocks at standard bore if anyone in NW Oregon or SW Washington is in need.
Needing to use a smaller bore you might want to really consider intake valve shrouding. It might be better off with a 2.14" valve than a 2.19" or bigger.
Chrysler never cast any block for cold weather. That's a silly notion spread on the internet.

I am not aware of any 413s built out of 440 cores.

I am aware that there are industrial 413s that have the same casting number as 426s. I assume they could be bored out to 426 size no sweat, and 4.29 most likely, but after that it is once again a crapshoot.

The R means regular fuel, surprise surprise on a schoolbus.

R.

And the 8 must mean culinders😂