Vapor canister parts??!

[zextrot]

I'm trying to replace the spring and diaphragm on the purge valve of my '72 RoadRunner vapor canister, but I have not been able to find where to buy the parts. DOES ANYONE KNOW WHERE TO GET THEM??

 

[moparmarks]

Did you try the dealer? May have to do a country wide search.

 

[72RoadrunnerGTX]

I'm trying to replace the spring and diaphragm on the purge valve of my '72 RoadRunner vapor canister, but I have not been able to find where to buy the parts. DOES ANYONE KNOW WHERE TO GET THEM??

Those parts were never serviced independently, part of ’72 one year only charcoal canister #3577584. Best bet is to find a used canister somewhere, any ’72 Mopar had this same one originally, taking a change the diaphragm is in better shape or keep a look out for an NOS one.

 

[zextrot]

if i get a replacement canister, am i good to go as long as i choose one with four ports like mine? mine also has a purge valve - i guess it doesn't matter what kind of purge valve is on the replacement canister as long as the vac lines route correctly?

 

[moparmarks]

Guess you need a 72 only can. The 73-up has 3 ports and no valve.

 

[zextrot]

i just need the spring and diaphragm that's in the purge valve.

 

[72RoadrunnerGTX]

The ’72 canister (4-port) system uses a two stage purge flow rate controlled by the purge valve and a vacuum signal teed off the vacuum advance line (the fourth port on the ’72 canister). The diaphragm is the weak link on that canister after all these years. The test is pulling the fourth port down with a hand held vacuum pump, should hold a vacuum. If not there are pin holes in the diaphragm and will create a vacuum leak condition for the vacuum advance system and poor running as the carb timed port for the advance will be leaking and little to no vacuum advance. Since correct new or NOS replacement parts are almost nil, short of replacing the canister with a known good used one, I would recommend blocking off the fourth line to the purge valve and living with the lower purge rate.

The ’73 and up 3-port version is designed for use with OE carbs having a dedicated timed purge port rather than being teed into the PCV line as in ’72. To run the later canister on engines/carbs not having this dedicated port (all ’72 and earlier OE and aftermarket carbs), I would tee into the PCV line with a restriction in the line similar to the .030” restriction indicated in the ’72 diagram at idle. Again, lower than designed overall purge rate but still somewhat functional without adverse effects to engine operation.