Breather help

[vitamin_c95]

So i added a spacer under my edelbrock to stop my mild case of vapor lock. The tube that goes from the passenger valve cover to the air cleaner must be 49 years old because it has no flex, hard as a stale cookie and no longer reaches. After some searching on here, I see some of you have added the breather filter. Where are you guys getting it from? I can't find any that fit. I measured the diameter an it's 3/4" OD. I have a bigger diameter one on there now, $hit rigged to fit just to keep the engine sealed.

[71gmcC15]

I went to o'Reillys and had to relly look and i found one. The guys there thought they were all the same size so they whare no help. Also had to find a new grommet. Wich they also had.

[Pro299]

I couldn't find a fitted form hose either so i just used a heater hose and a 90 degree elbow in the valve cover. If i come across something better I'll replace it, but it seems to work fine.

[vitamin_c95]

Yeah, I was at O'Reilly too. He even let me behind the counter to get a better look while he checked the computer.

I debated heater hose. We will see. This one I have on now was bigger, so I made a makeshift shim/gasket.

I've gotta stop typing in this forum with my phone. I just edited all.my grammar.and spell errors.

[FirstOwner69]

I don't remember the hose on my '69 ever being soft or flexible even when new in 1969. I think that if it's too soft it could collapse in use. Be aware that the part that snaps into the valve cover (see below pic) is not a filter. It's actually a flame arrestor. Info in this thread.
https://67-72chevytrucks.com/vboard/...d.php?t=703532

[vitamin_c95]

Originally Posted by FirstOwner69

I don't remember the hose on my '69 ever being soft or flexible even when new in 1969. I think that if it's too soft it could collapse in use. Be aware that the part that snaps into the valve cover (see below pic) is not a filter. It's actually a flame arrestor. Info in this thread.
https://67-72chevytrucks.com/vboard/...d.php?t=703532

Good info. I read about flame arrested, didn't think that's what it was.

[maverickmk]

Originally Posted by FirstOwner69

I don't remember the hose on my '69 ever being soft or flexible even when new in 1969. I think that if it's too soft it could collapse in use. Be aware that the part that snaps into the valve cover (see below pic) is not a filter. It's actually a flame arrestor. Info in this thread.
https://67-72chevytrucks.com/vboard/...d.php?t=703532

The hose shouldn't collapse as there is positive pressure from the crank case to the carb/air cleaner. PCV: Positive Crankcase Ventilation

[vitamin_c95]

I found a source up in orange county. But if it doesn't flex, I guess I'm back to looking for a breather that fit correctly

[vitamin_c95]

Think I found a k&n one via website.
#62-1360
Looks like O'Reilly can get it tomorrow, or a week thru Amazon. Thanks for the replies, everyone

[FirstOwner69]

Originally Posted by maverickmk

The hose shouldn't collapse as there is positive pressure from the crank case to the carb/air cleaner. PCV: Positive Crankcase Ventilation

Help me understand.
Isn't the flow of air to the air cleaner via the breather hose and from the PCV valve to the carburetor the result of the high volume of air drawn into the engine via the carb creating a vacuum as defined by Bernoulli's principle which says the higher the velocity of a gas or liquid, the lower the pressure? If so, and if the flame arrestor were to get plugged the resultant vacuum could possibly cause a collapse of an overly flexible breather hose. Granted, it would have to be a pretty weak walled hose.

[geezer#99]

Hopefully you guys understand the breather line to the valve cover is air supply into the motor. You need air flow in to mix with the crankcase fumes and moisture and drawn out by the pcv valve.

[FirstOwner69]

Originally Posted by geezer#99

Hopefully you guys understand the breather line to the valve cover is air supply into the motor. You need air flow in to mix with the crankcase fumes and moisture and drawn out by the pcv valve.

Are you saying the breather flows into the engine via the carb as I described it or the reverse flow to the valve cover? We all may be saying the same flow directions.

[geezer#99]

The air flow is from the air cleaner thru the hose into the valve cover.
That’s the intended direction of flow.
I’ve seen it described on this thread as the flow going the other way.

[maverickmk]

My understanding is there is pressure created inside the motor from compression and windage and if this pressure is not able to be relieved by a breather, PCV etc then things like the dip stick pop up and oil blows all over the exhaust, weak seals start leaking oil. But, as I think about it there would also a vacuum created by the carb to draw out fumes from the motor to be burned off, so there would be potential of the hose (very thin hose like FO69 said) to collapse or restrict. Also, I could be completely wrong

[geezer#99]

Crankcase pressure is created by combustion gases getting past the rings.
Carb doesn’t create vacuum, it controls it.
For the hose to collapse you’d need way more vacuum than the motor creates. It’s a long ways from that breather hose on into the motor on one valve cover, thru the motor to the pcv valve on the other cover.

[yuccales]

Would using the metal tube like this pic shows, get you the added inch you need due to the spacer?

[HO455]

For that hose to collapse from vacuum you'd have to have one seriously dirty air filter.

[geezer#99]

Originally Posted by yuccales

Would using the metal tube like this pic shows, get you the added inch you need due to the spacer?

That would work but easier to use one of these.

https://www.plumbingsupply.com/inser...gs.html#90ells

Available at your local hardware store too.

[FirstOwner69]

Originally Posted by geezer#99

The air flow is from the air cleaner thru the hose into the valve cover.
That’s the intended direction of flow.
I’ve seen it described on this thread as the flow going the other way.

That makes sense. Thanks for the clarification.