6 Pack Issues

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Phenolic spacer try that first yes the heat from the intake causes the gas to boil off...in mild cases its a long crank start in OP s case vapor lock. Also check the fuel line under the hood make sure it is against the frame as far away from the exhaust as possible 1/4 to half inch makes alot of difference use mechanic wire if need be to pull it back from exhaust.
 
I’ve been running a 6 pack on my 340 for a long time. The only thing I’ve had to do recently is install a fuel pressure regulator and gauge. These carbs do not like a lot of fuel pressure. Right now mine is set to 3.5 psi which works great. Without the reg it was running 8 psi and the floats could not control it resulting in flooding out and having to wait about an hour or that trying to start by holding full throttle until it caught and cleaned out.

I’ve only had vapor lock (boiled gas) one time at the track when I was not thinking and ran a new feed line right where the open headers were blowing on it……you can imagine how I felt after discovering that.

Like other posters said- are you sure it’s a boiling fuel problem? Or is it a flooding problem?
 
Forgot to mention the reason for increased fuel pressure was I replaced the fuel pump. New pumps seem to have too much pressure for some reason.
 
It's probably been mentioned already but 6psi is recommended for the SB 6 pack. 195 thermostat also recommended with the setup. The exhaust crossover left open is also suggested . That said I'm running a 180 thermostat with out issues YMMV. Check to make sure the throttle plates are not sticking on the front and rear carbs. Early carbs had that issue. Tips and tricks for the Sixpack "bible" link is here: The 6 Bbl tips
 
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Eddie348 said:
Good evening. I have had 3 occasions of Vapor Lock (I believe) after the 6 pack was installed. Also installed a new accel coil when the 6 pack was installed. Nothing else. Car runs fine until it sits for a bit or it's hot outside. After 1 to 2 hours of it sitting the car starts up again.
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Maybe the coil is the problem. I would try putting the original coil back on and see what happens.
 
Never have had this problem with my 6-pack. I believe it's boiling gas. That's what happened to my 318 after a gas fill up. You never really know what your getting unless you have the stuff to check it. I used to haul fuel, I know all of the possibilities.
 
Good evening. Hope everyone had a great weekend. Update - coil changed and the issue still remains after around 30 to 40 min. It shuts off. Tomorrow checking spark and taking it from there. Appreciate all the assistance on this matter. Big thanks to Rob
 
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