440 Charcoal Cannister Vapor Lock

Tech Question


Jon Mickley, Bossier City, LA, 1972 Plymouth Roadrunner 440

I’m restoring my one owner (me) Roadrunner.

The engine is mildly modified with a Comp Cam, roller rockers, Schumacherheaders, and .030 over pistons, and an Edelbrock Street Performer manifold,a Holley Street avenger carb and Holley mechanical fuel pump. It will bedriving mostly on the street and not raced. Came with factory air conditioning which I’m keeping but converting to a Sanden compressor and R134.

I have a question regarding the vapor lock canister/fuel filter that camewith the 440 engined cars.

The speed shop I bought the carb/fuel pump from says it’s not needed, thatthe newer technologly carbs and fuel pumps are engineered to prevent vaporlock. This speed shop also deals with Chebbies and Ferds, so automaticallythey’re suspect! So what do you, the “real” MoPar experts say? Keep the cannister, orleave it and just cap the return fuel line?

Thanks in advance for any help you can give me.



“Restoration”? Mmmm, I guess not.

Anyway, the charcoal cannister had nothing to do with vapor lock. It was anemisisons device, to reduce fuel evaporating into the atmosphere. It does noharm, merely collects vapors from the carb’s fuiel bowl vent and returnsthem to the tank as solid fuel.
The Holley carb undoubtedly has the bowls vented to the atmosphere, soyou’re question is really moot. But running a “3 prong” fuel filter, andrunning the middle nipple back to the tank via an unused old vapor returnline really does help to minimize vapor lock. The cannister will be justexcess baggage at that point.

The technological improvements in carbs ahve been really quite small overthe decades, and there’s been ZERO improvement in vapor lock areas. Ifanything, with today’s high-RVP, ethanol blended “gasoline”, vapor lock isworse than ever.


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