return line to tank

[Saltshaker]

Warm here today and I’m have a problem with fuel boiling. Will a return line solve the problem? Does it need a by pass regulator or is there another way?
Jon

[gregaba]

How warm is it were you are at and what are you driving.
Its gets hot here [Have seen 117] and I have never had a fuel boiling problem except in my flathead engines in the 60's.
If you are boiling fuel this time of year I would check my fuel lines and see if one has got loose and is againest a header or exhaust pipe. I would check the output of my fuel pump when cold.
Greg

[frnkeore]

I had a Falcon 6, that had that problem. The fuel line runs over the top of those heads (In & Ex on the same side).

So, I would look for areas that a fuel line is running over any exhaust pipe areas or exhaust manifolds.

If it persist, you can try a small fuel line or trans cooler, after the fuel pump, keeping all lines as far away from the haust system, as possible.

[My427stang]

It really depends where it's boiling

If you are boiling the the carb, it may do a little as it keeps recirculating the fuel before the carb.

Some tricks though, cool the engine with timing, reroute as much of the line as you can, get some airflow under the air cleaner, phenolic spacer, and even gas formulations boil differently from brand to brand.

That being said, if you do add a return, you want the regulator as close to the carb as it can be, so the fuel dumps just before it gets to the carb.  If you do it down by the fender, you arent changing much.  EFI systems I try to feed the injectors and dump on return side, but no matter what you do with a carb, at some point, it's just a dead0head hose feeding a needle/seat, shorter the better after a return system

[Saltshaker]

checked the fuel lines and I hade the line to the carb running between the dist and the expansion tank
will reroute that tomorrow
thanks, Jon

[Cyclone03]

If it’s a new problem replace all soft lines and make sure all clamps are tight. I did a lot to mitigate a fuel boiling problem when I lived in Texas but an air leak on the inlet side of the pump caused most of my problem

[fryedaddy]

i have had this problem many times this time if the year is when it happens.winter grade fuels are still in some pumps.winter grade fuels will boil easy in warm spring weather+i use 91-93 no ethanol it dont boil as easy either.it even boiled in my lawn mower when i used reg with ethanol.i bet if you throw some better fuel in it preferably with no ethanol i bet it will solve your problem

[Falcon67]

A heat shield between the carb and intake would be worth a look after line re-routing.  If you run an cast iron intake with exhaust heat crossovers open, then a shield under the carb spacer would be a consideration.

As for the return line - yes, a return style regulator plumbed after the carb would be required for proper fuel pressure regulation. 

[RustyCrankshaft]

The only 2 things I currently run on a regular basis with a carb is the boat and my 73 Camper Special. The 73 has headers and AC so the engine compartment gets toasty. With a plastic carb spacer I've never had any trouble even in 100*F weather. Before the spacer it would heat soak and boil the bowls when it got in the 90's. After the spacer never had an issue. Tried insulation on the fuel lines, etc, but the carb spacer is what fixed it.

The boat was fine on non-ethanol but with E10 in it started having boiling issues. Swapped to an aluminum intake and that helped a ton (ex crossover blocked), but again, after a 1" plastic spacer haven't had an issue in 3 or 4 seasons no matter how crappy the gas is.

[Falcon67]

Except on the race cars, I usually run a 4 hole Moroso synthetic spacer.  Solves a bunch of problems with heat and they don't melt.  DO NOT - IMHO - Use the plastic generic units from Summit/Jegs.  I have tried those and even on a engine with an aluminum intake and blocked heat ports they deformed rather badly. 

[fryedaddy]

i put a 1 inch pneumatic spacer on my 428 and still boiled the winter grade fuel.like i said needing better fuels  is the main problem because if it boils in my lawnmower and weed eater too.i cant put spacers on my lawnmower. ask Jay,he will say the same thing