i have a HD with the 317s and i have been thinking of swapping heads out to a set of 243s.
not for any race reasons but merely for better fuel consumption,i was just wondering if anyone has done this for ***** and giggles.
the concept,seems to make sense to me.
my truck is bone stock.
thanks
Ed

 

i dont see that swap accomplishing your goals of fuel mileage.
Probly better of with a tune to try to get mileage

The head swap will gain compression because of chamber size!
317s have a 71cc chamber vs 243s 64.4cc chamber

You will gain a little airflow flow but not much roughly 20cfm on the intake and 10cfm on the exhaust at 550 lift

dont see this worth it for you to make the swap or fuel mileage

 

If you did save any on fuel with the new heads. It would probably take ten years to pay yourself back. Now the added torque from the compression will be nice.

 

I dont think u will gain much at all, if you want more compression just mill the 317's,