Crankcase ventilation
Thread Starter
Pro
Joined: Oct 2005
Posts: 541
Likes: 1
From: Freeport FL
Crankcase ventilation
What's everybody (non-stockers) doing about this? My old engine just had hoses coming up off the valve covers to the air cleaner area. Pretty poor setup. My air cleaner base has a knockout in it, but I dont see really what I could put there- seems it would be up to me to make something up.
I consider plumbing it to the big vac line at the base of the carb, but the brake booster is already going there, and IIRC there is some concern about oil fumes eroding the brake booster, so that might not be too good.
Then there is the option of just putting breather caps on the valve covers, but then I dont want an oily mess all over my engine either. I would think they have foam in them to trap the oil, but ???
Ideas? Photos?
I consider plumbing it to the big vac line at the base of the carb, but the brake booster is already going there, and IIRC there is some concern about oil fumes eroding the brake booster, so that might not be too good.
Then there is the option of just putting breather caps on the valve covers, but then I dont want an oily mess all over my engine either. I would think they have foam in them to trap the oil, but ???
Ideas? Photos?
Instructor
Joined: Sep 2007
Posts: 198
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From: Colorado Springs Colorado
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Is there a vacuum port in use at the back of the manifold?
You want the PCV valve in the driver's side valve cover, with the vacuum tube getting vacuum from the manifold.
Then install a breather in the passenger side valve cover, and you're done.
Having the brake booster and PCV on manifold vacuum is best so make sure the booster vacuum line is getting manifold vacuum and not ported carb vacuum.
Also, make sure there is a filter in the line to the booster.
You want the PCV valve in the driver's side valve cover, with the vacuum tube getting vacuum from the manifold.
Then install a breather in the passenger side valve cover, and you're done.
Having the brake booster and PCV on manifold vacuum is best so make sure the booster vacuum line is getting manifold vacuum and not ported carb vacuum.
Also, make sure there is a filter in the line to the booster.
Thread Starter
Pro
Joined: Oct 2005
Posts: 541
Likes: 1
From: Freeport FL
The only real source of vacuum I have is the big pipe at the rear and base of the carb. As I will be running my B&M 144 (roots) blower, there is nothing really usefull to pull off the manifold. The only conection there is for my boost gauge, and this is where I will tie in my power valve circuit and my dizzy advance.
You dont think tying into this same carb line where the booster is currently connected is an issue as long as I use a filter on the booster to keep crankcase fumes from the booster?
You dont think tying into this same carb line where the booster is currently connected is an issue as long as I use a filter on the booster to keep crankcase fumes from the booster?
Thread Starter
Pro
Joined: Oct 2005
Posts: 541
Likes: 1
From: Freeport FL
To further clarify, this big pipe on the back of the carb (Holley 850) connects directly to the bottom of the carb. There is always good vacuum there, as its is sitting right about the spinning blower blades. Anything below the blower (manifold) sees sometimes vacuum, sometimes boost, depending on the driver's foot position 
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I personally wouldn't share the lines. Likely you'd get too low and the brakes wouldn't function properly.
If you have to it'll work but maybe not the best.
Have you thought about a Hydrobooster instead of a vacuum brake booster? The Hydrobooster is powered by the power steering system for the brake assist instead of engine vacuum. The unit itself is smaller, better looking and has much more performance than a vacuum brake booster.
If you're intrigued, PM me your email address and I will send you an information file on the Hydrobooster. It's not a 'fix' for your PCV issue but it will not only allow you to use that one source for the PCV but it'll let you keep good solid brakes no matter what the vacuum level of your engine. It's also smaller and looks better in place of the large vac can.
The chrome sleeve over the accumulator and the chrome master cylinder are things I added. Normally the accumulator is gold.
Thread Starter
Pro
Joined: Oct 2005
Posts: 541
Likes: 1
From: Freeport FL
Mmm....let's see if I understand here
So what you are saying is that if I try try to use this vaccum source to evacuate the crankase, AND run the brake booster, I will possibilty lose too much vac to the crankcase and then not have enough vac for the boster?
This would explain why the PO didnt do that, and only ran hoses from the valve covers up to the carb air cleaner area, which only intermittently resulted in the carb ingesting the blow-by, which was considerable due to the S/C.
Intresting, yes, I better have a look at this hydro boost thing.
So what you are saying is that if I try try to use this vaccum source to evacuate the crankase, AND run the brake booster, I will possibilty lose too much vac to the crankcase and then not have enough vac for the boster?
This would explain why the PO didnt do that, and only ran hoses from the valve covers up to the carb air cleaner area, which only intermittently resulted in the carb ingesting the blow-by, which was considerable due to the S/C.
Intresting, yes, I better have a look at this hydro boost thing.
Le Mans Master
Joined: Apr 2000
Posts: 5,202
Likes: 10
From: cincinnati ohio
St. Jude Donor '09
To keep things nice and dry under the hood you should run a PCV system of some sort. I don't know if a carb spacer with an additional vacuum port would work for you or not.
The hydroboost would eliminate the need.
I have a PCV valve in the drivers side rocker cover and an clean air intake hose in the other routed to a puke tank type breather...
The hydroboost would eliminate the need.
I have a PCV valve in the drivers side rocker cover and an clean air intake hose in the other routed to a puke tank type breather...
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