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Probably not...too much back pressure, that is what started the use of vacuum pumps, NHRA was making mufflers manditory so everyone put them on but couldn't evac the crankcase...enter the vacuum pump.
 

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Montgomery Ragland
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Will the evac system work will mufflers

no it will blow oil everywhere from the back pressure. Learned that one night trying to be nice to the neighbors Soccer:
 

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TURBOBULLET.COM BITCHES!
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if there is any back pressure in the exhaust at all it will pretty much seal the crank case.. The backpressure keeps the one way valve closed. I tried this way back in the day and it blew the dipstick out, as well as the intake seals... Oil was everywhere. :smt093
 

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3 1/2" flowmaster single chambers and tailpipes out the side without an issue on both a BBC and SBC.
 

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Probably not...too much back pressure, that is what started the use of vacuum pumps, NHRA was making mufflers manditory so everyone put them on but couldn't evac the crankcase...enter the vacuum pump.
Vacuum pumps were in use long before NHRA's muffler rule. Why? Because they make vacuum and evac systems do very little, with or without mufflers.
 

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I had evacs on 3 1/2" bullets that dumped just in front of the rear end, Pulled the evac tube at the valve cover off ... there definitely was a vacuum, worked great for me, thats just my junk though.
 

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Not a Hemi!
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had them on bbc elcamino with 3 inch flowmasters worked fine
I had the same mufflers. All it did was make my car smoke... real bad. They wanted to check the track out cause they thought I was dumping oil. I disconnected the hose to the breather and the smoke screen stopped. I had full exhaust to the rear axle, mufflers at the end and turn downs before the rear.
 

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Mine worked great at the end of the muffler outlet, also had the correct seperators on the valve covers. I didn't (or thought of it at the time) have a vaccum gague until the pump went on, i wonder if anyone has checked the e-vac efficency? Would it pull a vaccum at high rpm's? I'm sure nothing like the vac pump does......... TK
 

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i wonder if anyone has checked the e-vac efficency? WTK
An evac system is only slightly better than a regular, old breather stuck in the valve cover. You might see 3 or 4 inches... maybe 5. Basically, you're trying to overcome the positive pressure caused by blow-by. You're trying to prevent oil leaks and keep the gaskets from being blown out of the engine.

With a pump, you can see vacuum numbers in the mid- to upper-teens. You improve ring seal and gain horsepower.

This stuff is probably not a good idea for street-driven cars.
 
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