1: 460 Build	2: SCJ "old" flow numbers	3: SCJ "new" flow numbers	100: Electric fans
25: Header Evac

















a

Note, I have seen header evacs used with mixed results, same with useing a cheap vaccum pump set up. Last problem was solved useing a real wet sump vacum pump from aerospace. But, here are some pics of setups that I have seen work.

There is some discussion below about this angle, I have done two of these that did work, one that did not, take it for what it is.

This setup was tried with a new Corvette pump, it seemed to do allright, dont think the engine was sealed up well enough, it would still blow the dipstick at max rpm.

A:------------------------------------------------------------------

I understand the theory behind both, vacuum pumps and collector

'suction' tubes but is either one actually a practical system for a

street machine? I see a lot of both, but sometimes people do things

more for appearance and the 'in' thing rather than for practicality.

As far as a evac pump system, what is consisted in a typical system.

What is the estimated cost for a complete system and are there any

salvage yard pieces that can be used? I realize that there are

probably a lot of variables but I'm talking about something for a

Re: Evac. pumps and collector tubes for dummies

BBF truck pumps work well, plumbing is very straight forward. Plumb

outlet to a catch can. If the engine is not sealed tight you will

just suck in a lot of uotside air with no advantage. On our engines

that pull high pan vac you can here the air entering the engine for

a good 20 seconds after the engine has stopped running. A single

retightening of the valve covers can yeild 5"hg if tha vac seems

Standard type crank seals usually don't like to hold much vaccum

since they were originally designed to keep oil and air in the

engine as opposed to keeping air from entering the engine.

..does not work well due to the backpressure caused by a street type

exhaust. I run the Vac pump sold thru SVO or who ever they call

themselves these days. It is a truck pump & does quite well. If you

use a good oil/ air seperater it will last & last. MIne is a race

Are you saying that even with straight thru mufflers off of tube

headers there's too much back pressure to utilize the evac with

I run Moroso rocker evac. pipes into the collecters on my street

car. They work, the system is dual 3 1/2" with homemade Flowmaster

copied mufflers. When the pipes come off at the track there is oil

in the collecter but not too much. It pulls enough vacuum to stop

Thanks Jacko. That sounds right to me as it's pulling an oil fog. As

oil and air never actually mix, most of the air would disappear upon

hitting the collector heat (with attached exhaust pipes), leaving

The tubes may have worked for Jacko but I have seen them not work

with full exhaust. His exhaust system is 3.5 inches so that may be

one reason it works in his case. On a street car I would lean more

B:------------------------------------------------------------------

Finally putting the finishing touches on my Street/Strip BBF. The

engine builder has recommended that I not just run breathers in the

valve covers and that I get set up with something to create some

My first question is if I run a pan evac system plumbed down to the

headers, will the benefits be destroyed if I run mufflers?

http://www.dragstuff.com/techarticles/vacuum-pumps.html

Are any of you running vacuum pumps (and if so, whose?) on your

I wonder if you could plumb the pan-evac into the muffler outlet

I just put on the miloden crankcase evac kit this weekend. Welded

the bung into each collector, its a piece of cake to hook up. I run

mufflers, and even at idle I felt a decent suction coming through

the hose...which would pick up even more at speed. I'm real happy

with it. Besides better ring seal and less noxious sludge build up,

It would be interesting to plumb a vacuum gauge into your valve

cover to see how much vacuum your crankcase evac system is actually

drawing. Even at low vacuum your evac is still reducing crankcase

pressure and fumes, which is always beneficial.

To get the most HP benefits, seem to come when you can subject your

My power brake vacuum pump creates over 20 inches of vacuum, to use

that I would need to step it down. Any thoughts on how to do that?

Then I would need to use and Oil/Water seperator tank, so no fluid

C:------------------------------------------------------------------

As everyone knows, header evac tubes work. Has anyone ever put two

on each header and y'd them together to produce more vacuum? Will

I think it would probably pull more volume, but the peak pressures

would probably be the same. Unless that increased volume was needed

If my memory serves me correctly, Moroso's or Mr. Gasket's

directions/diagram is WRONG! The open side of the angle cut needs to

be facing the rear of the collector towards the open end. It does

not need to be parallel with the flow and of course not facing the

flow. Believe it or not, I've seen them welded in, turned the wrong

Yeah, I'll angle them so as to build pressure...

in the crankcase better, maybe it'll have more compression! Don't it

work that way? Naa, just kidding. I make my own tubes and buy the

So what's your thought on doubling them up? Hmmm?

I thought it was backwards when I put mine in but followed the

directions.I'll be cutting them back out and turning them

I made mine out of regular black pipe. Cut an angle on the pipe and

then cut a small approximate 90* angle to that and face the short

cut to the back, then do a little fine tuning with a grinder. That

is harder to expain than it looks. Hmm, I guess a pic is worth a

I do things like that so I will always have something to fix. Why

didn't you tell me they were backwards when you looked at them?

I guess I did look at them didn't I? Wasn't it pretty cold out? Er,

Who's directions where they? Moroso, Mr Gasket or ? I've forgotten.

I think you'd be surprized at the vaccuum signals and how their

strength changes by how these tube openings face.

I have tried different positions on a running engine on the dyno and

found some INTERESTING results as to not only the direction of the

opening but also their position fore and aft. The opening angle

changes as the position in the collector changes. Opemings directly

rearward, openings toward the side and openings directly parallel to

the exhaust flow were ALL favorable depending on where and what

angle the tube was installed. There seems to be NO real correct way

D:------------------------------------------------------------------

What kind of HP gains with a nice vacuum pump...

over the header evac. system? anybody got any comparisons?

some info for you soon Bret, if we get it all mounted we will pull

with it friday. All said and done, it will have cost 800.00. Haveing

a little trouble finding anyone with experience with them, wondering

also if it would not be better to go ahead and run a dry sump, as I

believe I was told here that you dont have to run a vac pump with

dry sump, but an engine builder here runs both on his TWD, and also

the directions with the pump mentions it as well. ANYWAY, I 'll let

you know Late SAt or sunday how it FELT sounded and looked. May help

I have not tested a vac pump instalation on my dyno to see how much

it helps or hurts, but I did test a Moroso evac kit and it was worth

about 15 horsepower on a 630 horsepower 557 with no other changes,

that's alot in my opinion. Question is, you'll spend alot on a vac

pump setup, but will it gain 15 horsepower for every $50 spent?? I

doubt it! Here's a good one, has anyone ever run multiple evac

systems on an engine, ie. two or more check valves in each

collector, two hoses to a junction block on the firewall etc??

I have a nice vac pump from a 351 Ford that I'm going to mount on a

bracket to allow for easy instalation on my dyno. I want it to be

able to work on any engine with a single V belt. It'll be

interesting to see how it helps with a given amount of depression,

since it takes horsepower to drive the pump it's probably a road of

deminishing returns. I'll post my results after I put this to the

Kaase told me that to much vacuum can cause oil pump cavitation. I

also found the same thing at the Reher/Morrison website under the

tech articles. They both say that the vacuum is trying to pull oil

from the pickup, making it harder to pump. I guess as long as you

got good oil pressure, it's nothing to worry about. I want to run

one on mine, too. Racinray runs one and he drains a fair amount of

water out of his catch can after every run. Dave

Peterson has a good set-up. It's a wet sump/vacuum pump combo.

It has four 7/8" vacuum sections along with the pressure section.

The vacuum sections are divided into two pairs with a suction port

for cach pair. You hook one section to each valve cover. It uses a

#16 oil suction to the pan. It runs around $800. This way you get

I use it as a 3 stage drysump pump(petersen said thats ok,its a

drysump pump anyway)..it makes about 7-8 inches vacuum going

downtrack on a 512.maybe capable of more,but I have cork v/cover and

Bret not knowing what type fuel or exactly what you are hoping to

accomplish it would be hard to say if the expense is worth it.If HP

is your only goal don't waste the money the increase is very

insignificant.If you run alcohol or run in high humidity then the

moisture extacted is more than worth it.Moroso and Aerospace no

longer have the market cornered.The pump I have cost far less.If you

are interested just post on forum and I will get info for you.

On a BBC, a 565" inch I think it was. Anyways, they were able to get

37 additional HP from it with no other changes, I think its kinda

I also read this article and all I'am trying to say is that is a

small amount for the money that it takes to set up a good system.I

have run my car with and without the pump back to back car ran a

5.91 with and 5.92 without that seemed insignificant for the $500.00

it cost to install.Don"t misunderstand am very pleased with the lack

of contamination the engine has since I started using it.But also

believe that small increases on a dyno do not always show at the

we set it up tonight, while the gauge showed very little vac((we

seemed to have some leaks)) the oil pressure which normally goes to

80 with rpm, only went to 60. Never showed more than 5" of vac. This

is an aerospace pump, driving a little faster 1.8:1 than recomended

1.6:1. Driver is worried. Motor seemed to respond real well when it

had differant headers and evacs. No signs of oil or steam out the

pump exhaust. Did all this in the shop, so not a good test overall.

I have heard about people taking the air pumps (or more commonly

called "smog pumps"), and spinning them backwards to create vaccuum,

it only makes about 5-6" (?) of vaccumm, and they claim that it

makes a difference. Its all junkyard stuff, so its very cheap to fab

up a system. If it dont work to satisfactory conditions, then its

On a 514 with 11.5:1 Compression in a 3845lb car the best Et without

a Vacuum puump was a 10.44 @ 130mph. I ran this combo for

approximatley 3 years and freshened it every other year with rings

and bearings. So this was as fast as I could get the combo to go.

Only refreshened the motor, and added a vacuum pump and went a 10.36

@ 131 on the second pass out. Pump was an Aerospace 3 vane, Sold the

Aerospace and bought a Moroso 4 vane and the car went a 10.22 @ 133.

Aereospace would only pull about 4-5 inches of Vacuum at full

throttle, the Moroso has to be limited with a relief valve and still

pulls 15-16 at full throttle at a slower spin speed on the vacuum

I think some combo's can really benefit from a Vaccum pump but like

anything else the combo needs to be at it's prime before installing

one. One other note, in my opinion Aerospace just plain sucks ! Not

trying to get a flame started but I have yet to have a good

experience with them, the pump housing will wear out before the

vanes do and thier customer service just stands out like no other

company that I have dealt with before. I also run their brakes

system too but would buy Wilwood given another chance.

E:------------------------------------------------------------------

I've reviewed the posts on this subject and the consensus seems to be

split on whether the exhaust header evac systems are effective or not.

I'm not concerned about oil residue from condensation being in the

collectors, but want opinions on if they can do an acceptable job of

There are lots of photos posted here with high-dollar engines having

just breather caps on the valve covers, with no pump/exhaust evac, PVC

setup, or other obvious method of relieving pressure. What are you

I run a 800 HP BBF (Drag Racing) and only use a large hose tapped into

the intake from the PCV Valve on the vavle cover and have never had a

problem. The oil filler breather cap on the other valve cover has been

siliconed shut except for 2 of the small holes in it. Seems to work

I run the header evac. on my race car (changing over to vac. pump and

dry sump) and my street car. Whatever you decide it is my opinion that

on a street/strip application you must run some sort of PVC system, I

don't like just breathers in the valve covers. You must draw the

blowby out of the engine in some fashion to reduce crankcase pressure

and oil leaks, whether it be by header vac, intake vac or a

Intake style will have stronger signal at idle than WOT (but your

Header style will be opposite, weak at idle but strong at WOT. (but

your contaminating the atmosphere) You could run the two styles

together with a "T" that way you have signal at all times.

Vac. pump will work at all RPMs and throttle positions and the reside

I agree the pump is ideal, I just don't want to spend the bucks as it

isn't a dedicated race engine. Nor do I want to contaminate the intake

mixture, so I'll stay with the header evac system. Randy, did you

place both breathers at the front of the valve covers on your street

engine to avoid the natural buildup of oil at the back? I'm using Ford

Street car has one at each end (stock FE pentroof covers)and full

lenght exhaust with tail pipes (3 inch all the way!)works great.

Ahhhh... So you run two from each valve cover? T them into one bung

Just one from each valve cover. Passenger side it's at back, driver

side at front of cover. Sorry for the confusion.

I haven't touched an FE in years and don't remember what the covers

look like. In any event, do the FE covers fit a 385?

FE valve cover won't work on 429/460 engine. n/m

As mentioned, I'm using the tall Ford Racing valve covers made for the

385, so FE fit won't be a concern. My thoughts were on breather

placement, and as cast iron 385 heads have a tendency to gather

drainback oil at the rear of the valve covers under hard acceleration,

I was wondering if the Edelbrock RPMs have that same situation. I

can't inspect the RPM drains, as they're on B/O, shipping the week of

8/5, so if they're the same drain as the cast iron heads, maybe some

valve cover baffle adjustment is in order. With stock valve covers,

that may be the reason some people are finding oil in their header

collectors. Scott has a set of RPMs but I don't think he has them

On the race car, the 466 that was in there was equipped with a pair of

iron CJ heads. The breathers were both at the back of a pair of sheet

metal covers with no baffels under breathers. Covers are very very low

and I had no oiling in headers, but a pair of oil deflecter would be a

good idea. Don't the tall FRPP covers come with a pair of deflectors?

Like I have said many times before I think some of the head drain back

problems are due to a mismatch of the drain holes at the head gasket

joint. Maybe its just me or if this is a bigger problem than me? Would

like to here some feed back on this, has anybody else seen this??

i havent contured it yet but i probly will on the next freshen

my evac trys to suck the rocker cover gasket in where the middle top

bolt is suposed to be,on fms covers those are deleated,so i put a

small 1/4 20 stud(very short)to hold the gasket in place

George, I posted on this subject a few weeks or so ago. I was going to

go the evac. pump route but was talked into the header evac. instead

by some friends. The reasoning was because of exspence, time and ease.

With my motor in the car (late model mustang), I had a lot of room to

run the evac. lines through the K-member to the collectors if I

installed them in the front of the valve covers. If I were to run them

from the back it would have been a very tight fit with the headers

etc.. One benefit is that in my car the engine sits a little high in

the front and that should aid in keeping the oil out of the lines. I

also have the FRP valve covers and using AN bulkhead fittings, you can

use the baffles that come with them. Also makes a nice looking

Georged, I would be more than happy to get you a picture however my

car is totally disassembled right now. The chassis is getting all the

final paint since the new cage and mini tubbs, the rear end is getting

powder coated, assembled a new lower end this past weekend, all the

engine bay aluminum is getting polished and so on and so on. I

originally thought the car would make Woodward Dream cruise but

absolutely not! Basically my evac. tubes are set up like this: 90 deg.

bulkhead fittings mounted in the front of the valve covers (breather

locations) which utilizes the baffles. Stainless braided lines run

down in front of the K-member behind the spring and into the bungs

located on the outside of the collector. I used a couple of Adel

clamps to hold the lines in place. If you try this, you may have to

get the 90 deg. fittings and Adel clamps from an aviation supplier. Or

give me a shout and I can help you out (I'm an aircraft mechanic)I

have loads of fittings in my box. Good luck, Gordon

I use a breather in the drivers side valve cover and use a PCV valve

in the passenger side valve cover with a inline fuel filter in the

between the carb and the PCV valve.I have used this setup for at least

6 years the fuel filter keeps oil from sucking into the carb.

Scoring disabled. You must be logged in to score posts. Respond to

my headers.I have expiremented placing the tubes in the collecters in

different places and depths the vacum would suprise you when it is in

I've got a closed exhaust, where would you say the best place to weld

in the tube for the evac. system, on my headers?

Do you have mufflers?Ihave never ran e vacs on a street car so I have

cant honestley tell you where would be the best place in your

application.I have found the best place on open headers to be about 1"

past where the collecter necks down.A friend of mine turned the

opening of the tubes around towards the wall of the collecters on a

set and he said it would suck the valve cover gaskets in.I built a

vacum pump one time that worked off a 3" water pump.It was a tube that

had a cone in side of it that pressurized water was forced through

with the pump.The cone increases the velocity of the water which

created enough vacum to pump water out of a barge.This was about a 15'

pull I cant hardly beilieve it worked but I saw it with my own

eyes.Everthing has to be in the right place for it to work properly.It

amazes me what air flow can do if properly controlled.

I hate opening the hood and finding the engine bay with a nice coat of

oil on it after every 1/4 mile run. Will the evac system stop this or

is there a good dipstick tube cover that I can buy that will hold the

If you seal the dipstick, that pressure will look for another way out,

with seals and gaskets being the easy targets.

A prior post stated the header collector crankcase evac system stopped

his dipstick from being the pressure exit point.

We hook a small spring (like a carb. return spring)through the loop on

the dipstick and through a tab on a water pump bolt. Holds the stick

down tight and is easy to un-hook to read oil level.

I'm going to relocate my header evac pipe, and that spring hold down

F:--------------------------------------------------------------------

The commercial kits come with no provision for using AN fittings and

ss braided hose. Other than tacking on threaded fittings to the

existing very thin metal fittings, does anyone have a better solution?

but it's very pricey. It has braided line, AN fittings and a check

G:--------------------------------------------------------------------

I did some testing this evening on an engine making a little bit over

600 horsepower to see the effects of the evac system that hooks to the

headers via check valves mounted on the collectors. The verdict,

Peak horsepower without 608 at 6200rpm, torque 660 at 4300rpm. With

the evac system hooked up, no other changes, 626 horsepower at 6200rpm

and 676 ft/lbs at 4300rpm. Everything else about the engine was

exactly the same no more than about 2 minutes between runs.

Now I would not want to jump to any conclusions after one isolated

test such as this one, but evacuating the crankcase is obviously worth

This particular engine is a Dove headed 557 with one carburetor. The

oil pan is the Moroso model for a 4 wheel drive truck application with

no windage tray. It's possible that this is an extreme case with 18

I think a lot has to do with the amount of blow bye as well as how

25hp is seeming pretty consistant for header evac stuff.

I think a little more could be gotten with more vacume. I wanted to

monitor actual crank case vacume, but the dyno only had one vacume

port and I wanted to monitor the intake for carb efficiency.

Maybe next time Ill take a stand-alone gauge and figure out some sort

of way to at least monitor the vacume. The morroso pump can be

overdriven enough to really pull some vacuum. I saw a difference of

25hp (well then the ehad gasket popped at 1020)

Kim,what do you use for an oil seperator,with your pump?

I have 2 of the 94 cobra electric evac pumps that are supposed to pull

10" of vacume. Im going to try and avoid another belt driven headache.

The electric pumps are fine so long as the motor is kept above the

impeller, the oil mist isnt a problem. Then expell it into small jas

I think I understand what you are talking about but, like they say a

There really isn't anything at all to the system I tested. It's just

two check valves, one in each collector, a piece of 5/8 hose and two

oil separators that look like they came from a Mopar 360 from back in

the late '70's. This kit was a Mr Gasket, but it looks just about

There was nothing tricky about how the pipes enter the collector or

anything. I do want to rig up something with a guage to see how much

depression it can muster, but I would say it could be a couple of

at idle, 1200 rpm the mopar breather will leave a kicky on my hand

I'm going to T into the line somewhere and connect my dyno vac guage

to see what it's doing. It seems to help power from just below the

torque peak on up on this engine. I was really suprised that it made

that kind of an improvement and this is a very tight engine with

i have my pvc line from the valve cover under the carbs on my 8-71

blower and the vac/boost gauge showes anywhere from 10 to 15 vac at

cruise. i guess i need a vac gauge at the carb base to see what it

i guess if i put my car on a dyno and pulled the line off on one of

big difference between the vacume at the carb and vac in case

Your supplying 15in or whatever vacume source to a 3/8" hose to the

case, but you do not have 15" vacuum in the crankcase. Your

measurement at the base of the carbs would be the difference between

the demand of the blower and the ability of the carbs to meet that

demand. 15" of vacuum is pretty bad for a race car, but pretty

At WOT, on my NA engine Im ceeping close to 1" of vacume at 8000 RPM.

From crack of the throttle till about 7500 RPM the manifold vacume is

If your running a PCV system and an open breather element odds are

your crankase is under pressure most of the time, to maybe dropping to

atmospheric, pressure when the PCV valve is open.

To run an honest crankcase vacume, no open sources that can be helped,

and it will take a pretty good vacume source to move all the

displacment of the engine out of the crankcase, as well as continue to

pull all the blow-bye out of a loose race engine.

Owner wants me to find an OEM pump that we can get from the yard to

replace the heeder evacs. Any suggestions? Electric would be great,

but we could with work run it of the crank(8000rpm). Anyone know any

make/model stuff to look for? Or are we getting enough from heeders

We done a flat top 598 with a mild roller cam and a set of C heads. we

installed a steffs vacuum system. At 1200 RPMs we ran it at 6 incn

vac. at 6000 it has 14 in. We Dynoed the engine on Kaase's dyno.

started recording at 4000 and pulled it to 7200. without the tank cap

at 6800 it pulled 961. 3 pulls never, shut the engine off. snapped the

cans lid back on 2 pulls at 984@6800. The #s were 20 more straight

down the chart. the most impressive though was watching the oil