I just recently acquired a 360 block, it's a 78 model. I am rebuilding it, bored 30 over, rv cam, headers, nothing real special. I have a set of 318 heads that were just reworked for another project and they didn't get used. The motor is going in a 4x4 and probably won't be seeing more than 4500 rpms. My question is, will these heads do what I want them to on the bottom end and mid range? Thanks guys!

 

Welcome
Larger valves would help and if your ambitious porting would be that much better.

 

Actually if that is all you are going to turn it up, the small port heads might even be a slight advantage.

Believe it or not, many years ago 78? 80? I wanted to "get rid" of a 360, and a friend & I had junked a Commando 273, IE 4bbl intake. I put those heads and intake on the 360. That thing was a torque monster in high gear on the highway, but about 3800 you might just as well have shut off the key as try to wind it higher. This was with the factory 360 cam.

 

What kind of cam are you thinking on running...?

The head's will limit you on intake, carb, and cam, size and selection.
if you intend to use these head's bigger valves will be the most important up grade.
i you try stuffing too much through those head's your combo will fall on it's face,

 

This is what i experienced i installed a 268 h in a 77 318 stock no compression changing. Edel performer intake 600 vac holle.
the car was way faster than the original set up.
up too about 4000 then after that i could feel the cam was star-vin for air/fuel !...

My motor head budi back in my high school day-s, use to throw a set of 360 head's on 318's and made them screamer's, man he was crazy 7000 plus rpm's all the time he tried to blow them up! On a simple head cam swap's+4bbl+any size carb! He's why i quit chevy and went too mopar...

Well as soon as i swapped out the heads i lost a slight bit on lower end but the gains to low mid too upper rpm range was huge the motor had so much available to it it worked effortlessly to inhale.. lol.
Then each new combo i increased the V.E. with out swapping the 1.88 s intake / 1.60 exhaust
my new combo is the best yet the little 318 eats up the rpm's so fast! She torque-e and has plenty of upper rpm power and is very street-able, she doesn't even sound like a 318 more like a 340 .
i have been trying to make a video running down the road but the mic.s cant handle all the db's.
With a 650 double pumper i would gain even more down the " unofficial 1/4 " ...

 

When you put the 360 heads on the 318s, were you shaving them at all to get the compression back down a little, or was it a direct bolt on swap?

I’ve heard doing the 360 head swap will make the engine sluggish on the bottom end.

 

With the small cam, small valves and high velocity from the small ports it will work well at the lower RPM's your planning.

My only question would be what year are the 318 heads ie combustion chamber size.

 

My first swap was straight no milling my buddy from high school use to do straight swaps also, not sluggish.. here's the trick though, you cant just put the largest duration cam in there you want but a dual duration cam will perform better, or install largest vales, 1.88/1.60 are perfect and some type of spread bore carb will help. Small primaries large secondaries.
The combo i have now has been milled real close to 0.50 the port job on the heads is what i think makes the difference the motor inhales effortlessly and she is torky at low rpm's.

i have been trying to get a recording vid/sound to post but the mic cant handle all the db's. and i get distortion