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Thread: Cranckcase Evacuation ? Reply to Thread
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  Topic Review (Newest First)
12-05-2013 11:08 AM
ernie Thanks for all the responses,gives me something to think about.
12-05-2013 10:16 AM
Gydyup PVC valve is ONLY to keep a carb backfire in the carb or intake from blowing into your crank case/valve cover.

The jegs kits are crap, but I put mine together using a 4 inch nipple from Home Depot 1.24, and two Pinto EGR valves from NAPA, total cost 15 buck I think. Already had the breathers, but will probably go with the screw ins on this build for peace of mind.

Catch can is only that, it doesnt do anything but catch blow by. Where as a positive evac is actively removing pressure from your crank case, that causes pressue and misting inside the eng, robbing horsepower. At idel around town, not to big an issue, and ring blow by is not that bad unless your eng is junk.

When you put your foot into it, and get on the big end of the track, you dont want oil blowing off your valve covers etc when your pumping all that press into your crankcase from the rings.
Thats why the header evac works well on drag cars, unless you can afford the pump. The electric pumps wont keep up with the increased crank case press on the big end.
12-04-2013 12:54 PM
ernie After reading others comments and experiences I have to wonder , lets say you run a big cam that really drops your vacuum ( 12''s at idle), now say while cruising , you have around 14 or 15 "s , wouldn't that drop your PCV valve efficiency ? Like I said early on , just wondering about keeping breather oil off valve covers ( the sweat) , factory stuff goes back to the air cleaner , I want to find a better way . I now think a recovery tank might be the way to go . Should this be done with no PCV valve and just a simple hose out of each valve cover ? Or with a PCV valve and one tank only ?
12-03-2013 11:07 PM
blow back

The set I bought from Summit have one way check valves that screw on right the included pipe that gets welded in at the header collector and so far I have never had a problem with pressure going backwards. The included pipes that got welded into my headers were notched and cut at the proper angle so they went through the perfect amount and proper angle to "suck" or "draw" the vacuum properly. There was no guesswork to it. And the weld has held fine so far without the need for any other type of support brackets.

The only reason my breathers blew out was because I had the evac hoses disconnected to try some different exhaust configurations. The reason I am going to the welded bungs with threaded fittings is for peace of mind, a cleaner more professional look, more clearance under my cowl and if I want to upgrade to a pump in the future I will already have that part covered.

Again, I hope that whatever you decide to do works for you. And I liked the post because I am always wondering if I should/if I shouldn't go to a pump so I like seeing the other members replies and reasons why they are for or against pumps....

Have a good one!
12-03-2013 07:10 PM

whats wrong with jegs or moroso kits...Mine from jegs blows backwards toward the valve cover...
12-03-2013 07:19 AM
Gydyup Really depends on what your Eng is built for. Stock to mild builds are fine running crankcase evacs off the Valve Cover to a breather or base of the carb etc, using a PVC in line.

But if your going with any amount of duration on your cam, rumpty rump, you will have problems with vacuum. Now depending on how much your running it, hi RPM etc, will dictate through the headers evac (mostly racing) or vacuum pump $$$$.

For mild street strip builds, the electric Ford vacuum pumps are fine, its when you get into sustained hi rpm runs that they cant keep up.
11-26-2013 10:03 AM
ernie Thanks,for the info.This header evac. setup you're talking about,from what I get from it is basically running your breathers down into your exhaust,where a factory setup would run into the air cleaner.Using an EGR valve would keep exhaust from coming up and into the valve cover ? If this is what you're saying,great info.! I guess what I'm lookin for is to keep the motor clean.An open breather does just that,lets the motor breath, and I'm looking for a way to keep the 'sweat' off the valve covers. How about just using a recovery tank? Something with its own remote breather and maybe a drain? Just a thought. Also,if going to the header route,do you still use a PCV valve? If not,with no vacuum being lost,you may have to lean out carb?
Any thoughts?
11-26-2013 08:03 AM
Gydyup Ive run crankcase evacs to my headers for years, through mufflers, on the street as well.

Never had a problem, made all the leaks and blowing caps go away.

If you go that way, braided is fine, but dont buy the moroso kit or Jegs. Got to Napa and get a couple of EGR valves for a Ford Pinto, one 4 inch X 1/2 pipe nipple from home depot, cut the nipple in half at a 45 and your done.

I do weld an extra backer on my collector the nipple goes through just for good measure. Ilooked at vacuum pumps, crank an electric, cant justify the cost against the effectiveness of the header evacs.

They will tell you it smokes, especially running through mufflers. Mine never has, anymore than any other car when your running the piss out of it.
11-26-2013 07:31 AM

It was recommended to me to do it but I'm running a blower and the pressure was blowing the breathers out. I opted to weld thread bungs in my covers and run braided line down to my header evac system. IF I still have issues I will go to a pump. I would say, if you are not drag strip ONLY not to worry unless you see the need. I have run regular breathers for years and NEVER blew one out till now. As for freeing up HP...... you would have to weigh out the need versus cost and the fact that every time a belt is added to the crank it takes HP away, even to make more. Plus added maintenance and belt alignment, etc......

Hope what ever you decide works for you,

11-26-2013 06:05 AM
ernie Thanks for the response, I guess the racers wait to see a problem and then install an evac. system if needed . I guess I'll see what happens , go from there . Thanks again.
11-24-2013 07:50 AM
mdross1 Recently finished a 427" sbc SB2 engine for a motorcycle because of wanting to run valve covers without breathers have no choice. During the build and asking around most that run strokers use normal crankcase evacuation unless there is a problem. I would suggest giving it a try using the engines stock pcv if the motor seems to weep oil that cannot be stopped then a vacuum pump would be the way to go. Good Luck
11-23-2013 02:44 PM
beatdown I wouldn't see why it'd be necessary. I'm building a street/strip 521. I'm also curious on this tho..

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11-23-2013 01:33 PM
Cranckcase Evacuation ?

Hi all, I asked this question a few weeks ago and didn't really get any kind of answer , so I'll ask again and see what happens ! For the street , is a cranckase evac. pump worth the expense ? Is a stroker motor , with all the extra pumping , building enough pressure to warrant this system ? I'm considering a 4.300" stroke in a DOVE A block and am considering an evac. pump for the street , has anyone taken this path yet , and if so how did it work out ? As always , I welcome any and all comments ! Thanks , Ernie

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