OK, I will admit this up front...I saw a car with two breather caps, and no line to the carb, so I copied his setup. I haven't driven it since then, but idled it in the garage for a while today, and noticed that smoke comes out of both of them. I used to see puffs every now and then out of the one, when my hood was off. I am wondering if I should put the vacuum line back on with the valve, and maybe even do it to both sides? Will I see any benefiit either way?
Just run one filter and a PCV valve in the carb base. All engines (even brand new ones) leak past the rings and valve guides. Sure there are arguments of gaining small amounts of HP with a crankcase vacuum or evac system. At our level of performance - forget it. Cleaver
i saw a car today at the track.. 87 fox body mustang... it had 2 filters on each valve cover.. not sure what he was thinking. but i am guessing it was over kill. i have 1 pcv on the passenger side going to the carb.. and the driver side is the oil fill. i need to replace the pcv.. its old.. and probably not efficient anymore
They are cheap but you only want one on your engine. A PCV valve is a controled vacuum leak and two of them are too much of a keak. You have to close your throttle plates down and adjust your idle fuel mixture. Then you have to adjust your accelerator pump stroke and timing to take the flat spot out. I don't need to tell you how I know but I never could get a decent idle out of that 289 until I removed the second valve. I didn't know that engine vacuum could collapse a valve cover!
pcv replacement Scott most people using double breathers on their valve covers are building some high horsepower and the pcv would actually lose power for them in this manner. The pcv (positive crankcase ventilation) recirculates unburnt blowby gases from the crankcase to the intake and so the engine can burn them. This method is used to lower emissions, it also makes engines like ours last longer because the engine running with a pcv valve doesn't build high crankcase pressures due to the valve vacuum applied by the intake. Lower crankcase pressure equals longer oil pan and valve cover gasket life meaning less leaks. On high horsepower engine they benefit nothing if they run a pcv valve this lowers their air/fuel mixture and increases carbon build up in the engine and lowering their horsepower. I hope you understand what I'm talking about.
Thanks guys. I kept all my pcv stuff just in case I went back to it. At least I now have a second filter for after I clog up the current one.
Running two PCV valves without some kind of breather defeats the purpose of running them at all. The PCV valve sucks the combustion gasses out of the engine (which over time contribute to sludge build up in a street engine), and the breather pulls fresh air in by way of vaccume. From what I have seen, V8's usually the PCV valve on one valve cover with a breather on the other, so that it effectively removes the gasses from the entire engine. My 6 cylinder just has one in the front of the valve cover with a breather in the oil cap in back.
AAAAAH! That makes sense...It is supposed to suck fresh air in the breather and through the valve covers, then out into the carb!!! So my problem with smoke is just worn rings? I need a rebuild soon???
The smoke is comeing out because there is no PCV valve to suck it in the intake and burn it. Instead, it's being forced out the breathers by pressure inside of the engine. Smoke comes out of the breather on my engine too, but only after I shut it off and the PCV valve ceases to suck the gasses in. I guess if there is excessive smoke, it could point to excess blow by, but if the engine isn't physically smokeing out the exaust, I don't know that I would worry about it too much... Just my opinion though..
You might also be interested in running one of these little units........ This one is from Steeda. However, you can easily pick up a filter/separator unit at Home Depot or Lowe's. Find them in the air compressor area. Just plumb it into the line from the PCV valve to the carb. Keeps lots of oil vapor from re-entering the engine and depositing on the valves/chambers.
Throw the PCV Valve in the trash!!!! Take the breather caps back and make sure you have the right fitting caps for your valve covers. I dont run a PCV valve, yes my motor has been rebuilt....but if it aint needed, then dont have it on there
