PCV Valve- Connect it to the carb or the intake?

[mrtleavitt]

I was wondering if there's a difference in these two places. I currently have the PCV valve going into the intake manifold. But there is a PCV port in my new carb. Will it make any difference in which place it's routed to? The only reason I ask is it might look cleaner going into the carb.

[eggman918]

I was told so I guess this is "hearsay" but if your carb has a ftg. use it because the carb is designed to pull air from that port

[ToughOldFord]

Use the carb. If you run it off the manifold the cylinder that is fed by that intake runner will run lean and possibly burn a valve.

[mrtleavitt]

That's good to know. Anyone have any links to some reading on the subject? Just want to know a bit more about it. That does make sense though.

[Dragon]

My PVC and my Vacuum booster run of the intake and boy am I sorry. Low engine vacuum and rough running cleared up as soon as I capped both of those ports off. I need an aftermarket manifold to move the PCV over to as my carb has no port for it and I have no Heat spacer.

So yes off the carb.

[mrtleavitt]

So are you saying I will get more engine vacuum if I run my PCV valve off the carb?

[Dragon]

yep it lets way too much air in.

[TNIceWolf]

As stated above.......if you run the PCV to the carb.... it gives a more evenly distributed mixture and runs less chance of fouling just one plug. Plus the oil vapors get more evenly distributed to each cylinder. That little bit of oil vapor can be considered top cylinder lubrication. Not a bad thing.

[Dragon]

As stated above.......if you run the PCV to the carb.... it gives a more evenly distributed mixture and runs less chance of fouling just one plug. Plus the oil vapors get more evenly distributed to each cylinder. That little bit of oil vapor can be considered top cylinder lubrication. Not a bad thing.

Only problem with mine is all my plugs show slightly lean clean condition no matter what. The hotel I am staying at won't let me work on the truck in the parking lot.

[austin]

what about an air cleaner with the inlet on it im sure that would work fine if your carb dont have one

i dont know if there is an aftermarket air cleaner with one of these such things but i know my 73 lincoln has one with a breahter filter and 69 IH has one thats on the inside of the air filter by the carb

[Dragon]

Most air cleaners have an inlet but the PVC valve is the outlet and it would coat your filter and carb with warm oil.

[eggman918]

what about an air cleaner with the inlet on it im sure that would work fine if your carb dont have one

i dont know if there is an aftermarket air cleaner with one of these such things but i know my 73 lincoln has one with a breahter filter and 69 IH has one thats on the inside of the air filter by the carb

I dont think air filter ftg. has vacuum

[austin]

i noticed a carb spacer with a pcv inlet that might be a good place for somone to put thier pcv

[ToughOldFord]

You're not going to pull a vacuum from an air cleaner. The port on the air cleaner is for the vent side on the valve cover opposite the PVC.

[mylifeswork]

When it comes to vacuum port access for PCV and Brake Boosters the PCV is best at the carburetor since there is flow from the crankcase. The PCV system is a controlled and designed vacuum leak to control HC's, hydrocarbon's. This controlled vacuum leak is best if shared with all eight cylinders instead of a few. Allows for equal fuel misture to all cylinders when connected to the Carburetor. Their shouldn't be flow from the booster since it only provides vacuum for boost and not flow. You could use a manifold source for the booster. If it runs rough the booster may be leaking and would need to be replaced. Simply pinch hte vacuum hose going to the booster while engine is idling. If the engine RPM changes and the engine smoothes out the booster is leaking. Concerning PCV systems you need fresh air to replace the vapor the PCV valve is drawing from the crankcase. That would be the other hose attached to the air cleaner housing and valve cover. You could use a breather only on the valve cover if your using a Chrome Air Cleaner without a provision for a hose to hook up to. The reason for running your breather hose to the air cleaner was an emissions function. This is called a type four, closed crankcase system. This prevented the HC's or raw gas vapor from the crankcase from entering the atmosphere when the engine was shut off. Another thing about PCV systems, many engine oil leaks can be blamed to poorly functioning PCV systems. If you see a valve cover gasket or oil pan gasket get sucked in the fresh side of the system could be plugged and the PCV valve is putting a large vacuum on the engine and finally a gasket gets sucked in so it can breath. If the system is entirely plugged it can blow out seals. I replaced a one piece seal on an engine because it blew out. After the repair the new seal blew out in 5 minutes. I learned a lot about PCV systems that day. Might be more information than you wanted but hope it helps.