I'm experiencing what seems to be a fuel vapor lock issue. My car is a stock 68 Charger R/T 440 with OE style fuel lines, vapor separator w/ return line, mechanical pump etc. I have the intake heat cross over blocked and a 1/2" wood spacer under carb.
I get what feels like fuel starvation at high RPM only after it has been run for a good 30-40 minutes and everything is good and heat soaked. It runs great when cold or during cool temps (like 75deg and under). I also don't have any problems just cruising or idling. Only under WOT at 4K RPM and above. Water temps are always 180-190ish. Also, if i jet the carb rich (like mid 11's on A/F guage) it seems to do better, but the problem will still show up after a while of running it hard.
Could it be that the vap sep/return line is adequate and slow engine speeds but at high RPM it can't get rid of all the vapor?? Just looking for opinions as i'm running out of ideas. I also want to keep factory equipment so no elec pumps or the like. It needs to look completely stock. Thanks for any replies.