65 401 Riv, Edelbrock carbI am checking out all my vacuum ports to see where one might be leaking. And I have a basic engine question. All the ports connected to the manifold or carb base pull a vacuum. accessories, brake booster, distrib advance, trans modulator. So they don't allow much air to enter the manifold/carb. EXCEPT ONE: pcv. it just sucks air thru the breather on the oil filler, thru the crankcase and into the base of the carb. Isn't that creating a lean condition? and cant that be connected to the air cleaner so that this is sucked into the carb along with fresh air? My guess is that it does add additional air so that you compensate for it with a little richer carb settings. But if you are running lean then can you just move this input to the air cleaner and plug the existing hole? I was originally blocking off all the vaccum ports to see if one was leaking. And I found this. If I just plug the port then the blowby stinks up the engine compartment and cab, so I hooked it up to a fitting on the bottom of the air cleaner.
I wouldn't jack with it Not that I'm a nailhead expert, but in general I wouldn't jack too much with PCV. Routing it to the aircleaner vice the carb base will cause the system not to function as it should. At the air cleaner you can bet the overall vacuum is lower, which would lead to insufficient purging of "blow-by" crankcase gases, which is a level of hell I wouldn't recommend exploring.... The car was basically built with the PCV in mind as to the lean/rich conditions, and is therefore an integral part of setting up the engine's intake route. If you have a low-vacuum condition, there is also the possibility that valve timing is off (I have this problem and will correct it shortly) or that other conditions exist causing the problem. Unless the PCV valve is acting up, there is a leaking hose, or there is a clogged breather the system is basically simple and infallible. In a nutshell, don't go there...
I'm no expert either, and I agree with Erik's advice -- don't jack with it. The air from the PCV is designed in to the system. What do you have for a gasket under the carb? There is an exhaust crossover passage on the manifold that is exposed at the carb flange that can create an "internal" air leak if not blocked off with the correct stainless steel plate and gaskets under the carb. If you've sealed off the crossover this won't be a problem, but otherwise could be the source of a leak.
Edelbrock carb - hmmmm - there's a little vacuum port that goes to the electric choke coil, and there's supposed to be a little rubber o-ring on it to prevent a vacuum leak. It's accessible by taking off the choke coil housing, and sometimes falls off without people being aware that its even there. PCV - the idle circuits are calibrated to have it. Since you mention you have an Edelbrock carb, plug the hose into the big port on the front side, at the base of the carb. You can use an 80's Buick V-6 PCV if you want a 90 degree angle for a cleaner installation and hose routing to the front. Are you still connecting the PCV to the plumbing mess on the rear of the carb, as was done with the stock Carters? That gets an oily mess in your power brake booster. Definately need the stainless steel between the gasket and carb if the crossovers aren't blocked off.
