Fairlane I picked up a couple weeks back had a nice Pro Systems 850 on it but owner didn’t include with the deal, but let me use it to get the car home as carb that was on it needed a rebuild. I had an AED 750 HO on the shelf, basically new, so threw that on it. It runs great but I’ve discovered it vapor locks BAD. Did it the other day rolling 50mph on a 80* day, several times bad enough to stall the engine while running along at 2500rpm. I pulled the air cleaner figuring it may be acting as a heat sink, it seems to have boiled over so bad it shot gas out the vents and hit the underside of the hood. I insulated the fuel line and drove it today, vapor locked again in 66* weather with engine at 180* just hitting two stoplights.
Just put the 850 back on it, ran the same exact route, stopped and let it get to 200* and shut it down to heat soak, let it sit for five minutes and started it. Ran absolutely fine on the way home, so I’m convinced it’s the carb and not general heat soak issue with the fuel line specifically
Anyone experienced this kind of issue going from a Holley to another Holley? I have a thick insulating carb pad to try but I’m not confident, it’s doing it on very mild days while moving so can’t imagine this’ll be enough but we will see. Any ideas what else to check?? Already checked fuel pressure, it was actually down to 3psi as fuel was boiling, 7-8 normally