Is this acceptable or do i need pcv???

[cody72sport]

i had set up my new carb like this, but my dad told me it would run too lean. i have new bronco logo valve covers so i dont currently have a pcv. i went ahead and put a plug on the carb instead, is this ok? leave the plug? figure out how to include a pcv?

 

[DirtDonk]

Nope, not ok unfortunately.
That's just a big (but filtered at least) vacuum leak. And so your dad is right. It'll run lean.

Paul

 

[DirtDonk]

What you're needing a PCV for, and what this filter alone is not doing, is to get clean filtered air back into the crankcase. You're just sucking it into the cylinders and bypassing the crankcase.
Eventually, you'll be seeping oil all over the place due to pressure buildup inside, if your valve covers don't have some way of venting.
How's about a pic of the covers? What's in them now? Caps? Filters like the one on the carb? Something else? Or no holes at all?

Paul

 

[cody72sport]

What you're needing a PCV for, and what this filter alone is not doing, is to get clean filtered air back into the crankcase. You're just sucking it into the cylinders and bypassing the crankcase.
Eventually, you'll be seeping oil all over the place due to pressure buildup inside, if your valve covers don't have some way of venting.
How's about a pic of the covers? What's in them now? Caps? Filters like the one on the carb? Something else? Or no holes at all?

Paul

one valve cover has a breather to the aircleaner, the other has a filtered breather cap, for now i have the port on the carb plugged

 

[Ohio Bill]

You should have a breather/fillercap on the left front valve cover. Then you should have pcv port on the right rear valve cover with hose going to port on rear side of carb (should attach to port on spacer below carb)

 

[Explorer]

For a neat install, there is a threaded port plugged on the back of your carb. Replace with fitting, run to a 90 degree PCV vale on pass rear valve cover and use a breather style filler cap on driver front. Then cap the front manifold vac port.

 

[00gyrhed]

you know you think youve seen everything then you wake up log on and get a chuckle.

Thanks,

 

[cody72sport]

you know you think youve seen everything then you wake up log on and get a chuckle.

Thanks,

hey im only 18 cut me some slack lol

 

[cody72sport]

so what will happen with breathers on both valve covers and the port on the carb plugged?

 

[Explorer]

It will vent, but still may have oil vapor escaping underhood. I just put a PCV system on my new engine for that very reason. Really old engines had a draft tube venting out the bottom to keep the vapors and associated mess out of engine bay. The more worn the engine, the more of a problem you'll have. It's commonly refered to as "blowby".

 

[70_Steve]

so what will happen with breathers on both valve covers and the port on the carb plugged?

Nothing catastrophic. But, besides adding more polutants to the air (unburned hydrocarbons, etc) your engine oil will become contaminated quicker, and cause pre-mature engine wear.

No matter how good the piston rings are, there's always a slight leak (blowby) past the rings. On the compression stroke there's unburned fuel leaking by, and on the power stroke, there's all the byproducts of combustion. The Positive Crankcase Ventilation (PCV) system is intended to remove as much of those contaminants as practical. It does this by causing a constant flow of fresh air through the crancase to pick up any vapors, and direct them back to the intake manifold to be burned.

The fresh air source is normally the air cleaner, through a hose or duct, to the drivers side valve cover, but a filtered breather on the valve cover is OK. Just make sure the breather is big enough. The air moves through the crankcase and up to the passengers side valve cover, where the PCV valve is installed to regulate the vapor flow. Then through the PCV valve and to a manifold vacuum connection. It is the manifold vacuum that causes the air flow through the engine.

Do yourself, your engine, and the rest of us a favor, and install the PCV valve.

 

[00gyrhed]

Got to get on the box for a minute.

Did you know that until the electronic fuel injection systems were utilized that the pollution control device that had the largest affect on pollutants from automobiles was the PCV system? They say that requiring its use alone in CA in 1964? automobiles had made a significant change in smog levels by 1968 even though autos on the road were increasing in number.

The PCV system is the only pollution control that actually delivers on its promises and is by far the best bang for the buck. Not only is the air much cleaner with them so is the engine compartment and the internals of the engine.

The use of unleaded fuel may be second.

Until catalytic converters were required smog pumps were a joke and an ecological catastrophe. They did nothing more than pump additional fresh air into the tailpipe to dilute the effluent, becuase our beloved federal government listed their requirements in ppm. They actually increased the pounds of pollutants per mile because it required addition HP (gasoline) to drive the pump. Even at the time studies were showing that the actual mass of unburned hydrocarbons was not decreased by the smog pumps. Whats really stupid is that a cam change would alleviate most of these pollutants.

They eventually found that even with catalyitic concverters air had to be injected into the converter as well to achieve real burning of hydrocarbons in the cat.

EGR valves are totally redundant if the cam is ground properly and compression ratios are kept within reason. In fact there were cam grinds availible in the 60s and 70s that would meet the federal requirments without the EGR valve and smog pump. Problem was they were high lift short duration (what we call and RV cam today) and the metalurgy of the time and the automobile manufacturers unwilliness to put a roller cam in every engine meant these cams might last 50K miles which was deemed as unacceptable to the amercican public. But I would have rather had the high torque and gas efficiency of one of these cams that the burdened engines they were producing in the 70s.

A good cam with very little overlap makes lots of torque and is preffered for street/offroading, even better with a roller cam. Couple that same cam with a modern EFI and a working PCV system and that vehicle WILL comply with federal standards without the catalytic converter or the smog pump.