gas cap question

[rsmarr1982]

my 72 k20 does not have the emissions on the gas tank i guess its called eec . which gas cap do i purchase a 67-70 since its not eec or do i still buy a 71-72 that says with eec even through i dont have that

[cdowns]

for 72 it should take a vented gas cap

[El Dorado Jim]

x2

[El Dorado Jim]

Originally Posted by cdowns

for 72 it should take a vented gas cap

x2

[hdff]

should a 71 be vented also?

[rsmarr1982]

i thought a vehicle with evap emissions would have a non vented cap so fumes would go through charcoal canister . 71-72 1/2 tons where required to have evap emissions . i have a 72 3/4 ton that does not have evap so i figure vented is what i need but would a vented 67-70 screw on a 72 tank.