Originally Posted by 69 widetrack
Just my thoughts...as Mr. P-Body mentioned, there are several guys on this forum that have you covered but, they can correct me if I'm wrong. I love the Demon Carbs but wouldn't you get more out of your engine if you upped the CFM to 750 or even a bit larger? I built a 428 Pontiac a few years ago and ran a Demon Carb even larger with great results...If I remember correctly it was an 850 CFM.
Like I said...just my thoughts.
the HEI needs to be upgraded,the stock HEI needs a better external coil.Im not sure what the 400 heads flow so get them tested and make sure the cam matches the heads.It sounds to me like a 13 second combination not 12.
Still not enough information.Are you using slicks or drag radials?