Technical 327 with no oil filler and breather

Now that's the stuff!

Looks awesome!

 

Well, like so many of the 'traditional' choices we make when building these cars, it depends. That the 'cross flow' PCV ventilation is superior to the earlier designs is unquestioned, but how much 'worse' those older versions can be can vary widely. Driving habits (do you drive enough to attain full operating temp for at least a half hour each time you use the car?), does your car run 'hot' or 'cold' (lower running temps won't remove condensation nearly as well), oil type/brand and how often do you change it, how much combustion product leaks past the rings and contaminates your oil (no rings seal 100%), how much venting area is there in the heads (SBC and SBF both suffer badly here as neither has any large openings to allow air circulation without positive pressure), all of these things will affect how much and how well the crankcase venting system will work. In my personal experience I've never seen large amounts of sludge build-up inside a motor in a 'cross flow' type PCV system but certainly have in older motors without it. As Gimpy pointed out, once these were adopted by the OEMs they were able to extend both warranty periods and length of oil change intervals due to the much better removal of condensation and contaminates.

Keep in mind the earlier types of crankcase venting was a holdover from the flathead era. There you didn't have any 'dead air' in the heads as all mechanicals were contained in the block. By the end of the '50s the OEMs knew they had a problem with the OHV motors and with the advent of emissions added the PCV system in the early '60s. While the 'positive' aspect of that design helped slightly by replacing the road draft tube, it wasn't until they added the cross-flow that it worked well.

So it boils down to what you're willing to tolerate and how much you want the 'look'. Go with the 'trad' looks but expect some reduction in longevity of your motor. You can mitigate this by changing oil more often (probably preferably by time, not mileage), in particular don't store the car without fresh, clean oil. Not to say your motor will expire early, but the chances of that aren't zero and will be certainly higher than if running a cross flow PCV, all else being equal.

 

Not a thing I can add to that!

 

I guess if I had the OP's problem trying to mix a modern intake with old fashioned covers; I'd put the "beer" can back in the valley, get the hose adapter like on '65 Chev and use matching PCV valve at the carb base. Then put a breather with a baffle as far forward as I could under the runners.
Since the block has that provision might as well figure out a way and use it.

 

True, the modern part has not ben mentioned but you can see the Nitrous bosses on it, that would be the first thing I would grind off

 

One other thing should be mentioned. Those aftermarket valve cover breathers weren't styling statements, they were installed for a reason. Pressure/vacuum in the inside of a motor can vary widely by RPM and as most of these motors were designed for a fairly sedate 5K RPM max, exceeding that can cause problems. Those breathers were a solution for when the OEM venting proved to be inadequate and/or to prevent spewing oil out the road draft and under your tires. If you look back, many of the full-race motors of the era had four breathers installed, two on each valve cover. But even just two were a pretty common fixture on the hotter motors.

 

I have a "modern" SBC so I don't have the road draft hole to use. I have the "modern" finned aluminum valve covers with PCV and breather holes and a C3BX manifold with the oil fill tube and breather. I had one guy notice that I had 2 breathers and he tried to tell me I was creating a massive vacuum leak letting that much air into the crankcase. He must not have known that the PCV valve meters the amount of air into the manifold and he is a car guy.

Gary

 

For what it's worth...'62 327 with the Latham taking up the entire front end. Original road draft tube, genuine vintage Offenhauser breathers (troll ebay for junker valve covers with vintage breathers) and a basic fill tube and stock cap...breathes great!

 

todays lesson in... "making things way harder than they need to be, because you don't want to change the valve covers"

anyway, that's what I took away.

 

I 1954 SAE Paper 540266 Ford discussed their new V8. The Y block.
The attached image includes FORD's comments about the efforts they made on the crankcase ventilation system.
I guess some might say they missed their mark because the Y Block had some sludge related issues (valve train?).
But 60 years later manufacturers sometimes get it wrong even with much more effective Positive Crankcase Ventilation.

 

Sometimes these old tech reports can make for some interesting reading. I was surprised to see that they found so much wear reduction at 20,000 miles or less with the full-flow oil filter.

 

You need to remember they were coming from the flathead V8 to the new overhead and many engines had oil filters in external lines as bypass systems. They also learned this with their overhead 6 a few years before. If Ford would have recommended and used detergent oil 99% of the passages to the rocker system would probably not occurred. All a moot point except for us who still use them today and have no need for outside oiling since we do.
One other point the decal on my glove box door recommended 20 wt oil on new 55-56 Ford V8’s; I doubt that happened as many used heavier oil from their past vehicles and old habits die hard..

 

How about connecting the PCV hose from the valve to the air cleaner instead of the manifold? No vacuum leak this way, but will it provide enough flow?

 

Won't provide enough flow. Remember that on the 'closed' PCV systems, fresh air intake is gotten from the air cleaner rather than just an open vent. The manifold vacuum is what makes it a 'positive' system.

 

Original Chevy "fresh air tubes" that connect to the air cleaner base are getting hard to find but they are being reproduced.
There are two styles, the straight one is 65 Chevelle/65-67 Corvette 327/350 hp.


The curved one like mine is 66-67 Nova, Chevelle, 67Camaro.

 

Perfect timing. Just brought home a 327. It has stock bore at 4.001, a set of rebuilt non drilled double humps with roller rockers, new bearings and two, new unused, sets of cam and lifters. One real thumpy and the other a wee bit milder. The plan is to put it in the ccpu steel top wide bed. Venting was on my mind when I stumbled across this thread. More posts please.

 

It is my understanding that by going with a wilder cam that vacuum pressure is diminished. Some have said that vacuum powered brakes can suffer. If this is correct, can I assume that this would affect the function of the PCV system? Would good breathers and a vented cap be the solution?

 

This right here, you can vent it at this spot, just weld a tube and put a push in breather from a valve cover in the end.

This is how I vented my corvette valve covers, indiscreet and let's the corvette still stand out without obstruction, same spot on both valve covers.

 

More breather bling.

 

You are speaking of two different systems, with two different functions.

Power brakes are a dead-headed system that is closed at the far end by a vacuum end, by the diaphragm in the booster. Vacuum is held in the booster by a check valve.

A PCV system is open, and depends on very little vacuum, clearing the crankcase by air flow.

 

There is a set of Keith Black breathers in the parts section, and I would love to run them on a set of Corvette finned valve covers on the 327 I'm building, but I hate to spend the money for them and not be able to see the "KB" when they are installed, that is the reason I want them, Kelly Burns = "KB"!