What would happen if I disconnected the small vacuum hose that goes to the canister? I am putting a holley on with an aluminum intake. Keeping the pcv hose to the canister is no problem, but the holley doesn't have a fitting to hook up the small hose.

 

Probably end up smelling gas, often the fumes were routed back to the carb for combustion in the engine. The PCV line is going to the canister. Either block off everything coming to canister (engine, fuel tank) or tee off another vacuum line to hook up the vac line.

 

Thanks. Does it matter where the vacuum line comes from? The original was near the top of the carb. The only open fitting I have is at the base.

 

I think that originally it would have been connected to a full manifold vacuum source. I would think it would run ok off the ported vacuum line as well, but it would not be able to pull off exhaust fumes at idle since there would be no vacuum at idle. The Holley should have both a ported and full manifold vacuum source and if you are not already using the full manifold for vacuum advance on a distributor I would use that one.

 

Thanks a lot. I believe I can get it to work.

 

I removed the pcv to canister line on my 1973 and have had zero problems, no smell ect:
I will look in my AIM and see exactly what its function is
Stay Tuned

 

U could have problems connecting it to straight manifold vac. GM connected that cannister to a ported vac on the carb as enough vapor could be ingested on start or at idle to stall the eng or at least make a rough idle. So they plumbed it to a connection thats ported above the throttle plates at idle position and the vac doesn't take suction from that cannister until the throttle are open enough to create the eng speed to handle the rich fuel vapor from the cannister.

Yeh i rebuilt my entire EVC sys and replaced the PCV too. Learned here on the forum myself that PCV is needed to keep a negative press on the crankcase even though its kind'a a controled vac leak into the manifold. But somehow the carb can be tuned to handle crankcase blowby and EVC vapor too. And the ECV is just a passive sys to take fuel vapors mostly from the tank and sometimes from the fuel bowls too after eng shut/down. Doesn't hurt performance but saves the enviroment a little bit each day. Yea i replaced that 30yr old charcoal canister and all the rubber hoses too. Replaced the fuel line flex and hoses back there at he tank too. So now i can sleep a night knowing my fuel system is working as good as possible.

Now i doubt those running fuel cells have a need for these ECV's but for most of us they won't hurt performance.

Well most Holley's made for the street will have a ported vac connection. U can verify this by looking for a slot in each throttle throat (venturi) and just give the little tubing connections a shot of canned air or even WD40 to see which connection flows there.

Now speaking of sleep i think i will enjoy some of that soon. Good night. cardo0

 

Thanks for the info. My holley only has one ported line and it's for the advance.