Hey all first time poster here

ive just picked up a 313 small block and want to have it bored out to standard 318 size but before I do I was wondering if anyone knows if 318 heads will bolt onto a 313 block

many thanks

 

The 313 has a smaller bore than a 318 , 3.88 to the 318s 3.94 bore but all the A motors used the same size valves so I can't see a problem. I could not find a definite answer for you as I'm not all that familiar with the polly A motor just what I've read over the years. So I hope this helps, good luck with your project.

Edit: I might be full of monkey poo!!!,
I just found this this thread on the H.A.M.B. give it a look, it says the valve covers don't even fit between the two motors.
https://www.jalopyjournal.com/forum/...vs-318.346301/
It appears after much reading that the 318 was the FIRST standard poly motor between all the manufacturers, that is they were all built to the same standard. So finding parts to fit on a 313 might be a crap shoot.
Good luck

 

Welcome.

LA heads cannot be used on a Poly block without extensive fab, welding and machining. The difference is where the water passages come out of the block deck. Poly heads can be ported and worked to make very good power. A quick search will confirm this in more detail.

https://www.allpar.com/mopar/a-engines.html

 

As I read it there are differences between the 313 between Dodge and Desoto and the 318 poly, but the 318 poly was the same between all of the manufacturers.
I assumed that he was still using poly heads witch may or may not fit. The article says you can put Hemi heads on a poly motor also but I don't know what ones.