318 heads

We use the factory thermoquad amd manifold even thou it is a major
mismatch to the heads.
I still race a 318 small valve 302 4000Lb Aspen /Wagon with stock 390 lift cam and stock compression/
heads/manifold/ carb when I am not feeling good enough for the faster cars. I was shocked how well the stock 302 flowed compared to
my best 202 X heads up to max lift of 390 on the same bench even with the tiny valves (Hint: well over 200 CFMS's with the
right valve job.

The Wagon held the O/SA NHRA record @ 11.83 @ 109MPH. complete with Roof Race and Air Deflector
for years!

To see it Google: John Irving Drag Racer
The valve job that flows great to or up to .390. Ime has been a big bowl hog that absolutely kills .475 and up flow, opening the throat up to the max is about the only one that comes to mind. Stock xheads are not known to be low lift performers ootb, the j does better. Stock x heads when I tested 2.02 @218-222 cfm while the 2.02 915 flowed 228-232cfm 'only one port did 232cfm'.
Stocker 318 1.78 -175-181cfm... hogged out flow 210-220cfm ime.
124cc stock... to about 135 +/- cc small valve ported to the above.
Great on a 273 or 318 but corks on a 6500 +rpm 340/360.
What did your 318 rpm at the trap @11's 1/4 with the heads you reference?