Do you use a pcv valve?

We're firing up my 440 at the machine shop in days. It's got ported sidewinder heads and the racer Brown st21 can. I was going to use a breather but I'm wondering if I should also use a pcv or pcv/catch can?

You should use a PCV on a street car. On a race car you can use breathers on each valve cover or some sort of evac system.

I use breathers on my street car. I also change the oil & filter at 1k, without pcv ,moisture can build up, so far I have not seen any when I adjust the valves.

I use two breather on my street and strip car too...
Pcv reintroduce oil fumes into the engine and I think it's not the best octane booster..
I agree pcv is good for everyday car

I do, always Moisture will condensate in your motor when sitting over night, the heat from the motor oil warming up the oil will help turn that moisture into steam (hot air rises)which the PCV will suck out removing it from the oil helping keep the oil in better, useable condition

Pretty much every engine up to the early 60s emissions era did not use them. Just had a pipe that turned down from a stand pipe on the valve cover, the old push on covers, vented to air. Either way engine must be vented. A good barometer on how the engine is lasting, no blow by, good, a lot, time for overhaul.

I always run them, my 434" small block made three more hp on the dyno with it hooked up.

Yes, a good tell tale of engine condition. Remember back then how at red lights the air would fill with blow by from some of the high mileage (over 50,000) cars waiting for green?

I was working in service stations in the early 1960s when CA mandated PCV, I think most of the standard Mopar passenger cars had them stock from either 1962 or 1963
The road draft tubes that hung down under the engines where relying on the passing air to help suck the fumes out of the motor, didn't work well at slow speed or when stop either
As far as the engine blow by hurting the engine if it is bad enough to see it is time to fix it
Water of any type in the engine oil or any other part(tranny, rear end) being lube is not good

Does a pcv need a certain amount of vacuum to work? Did anyone have issues with a low vacuum cam?

The better PCV do need a minimum, how much I don't, vacuum to keep them open. The cheaper ones will stay open most of the time when the motor is running
All of them I've seen and cleaned have a check ball and spring to close the ball when the motor is not running, not all of them will seal up when not held open by vacuum

Cab is right and its one of the reasons I prefer to run a PCV valve on my street car. Ron

I have been running dual breathers for 15 years with no problems. Never had any water in oil or condensation in valve covers when I have adjusted valves. Only time I could see it help if you start and run your car often for short periods of time and don't let it get warmed up.

Put a road tube on it.

That is true as short runs without letting the eng warm up is not good. Many run breathers and if you run the eng long enough all the time you may be ok but running a PCV valve setup will help make it better even on short runs and it has not hurt my performance one bit. I like it for the added insurance against moisture buildup in the eng and getting the blowby gasses out of the crankcase faster. Ron

So a pcv valve on one side and a breather on the other side would be a good set up for the street?

Yes. Ron

I run 2 breathers on my 440 The M1 and Dominator have no provisions for vacuum.Been like that for at least 15 years My son also ran 2 breathers on the 62 300 when he had it.Never a problem with it either and it had the OE motor.We just replace the draft tube when he put the cam in and drove thousands of miles.Rocky