blowoff valve question - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 14 Old 08-18-2009, 11:43 PM Thread Starter
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blowoff valve question

so my blowoff valve doesnt seem to quite "blow off" as much as it needs to, unless im WOT allthe way to redline I dont think its letting all of the excess air out of the system. i'm most likely going to cut back some of the spring in the unit to let it open easier. however i was wondering if there's any way to determine how stiff the spring should be. can i run the car with the blowoff valve hooked up to vacuum line and not hooked to the pipe? then i can press on the valve to see how stiff the spring is under vac? if so how hard should i have to press to open it?

as you can see im just searching for a way to get this thing calibrated correctly, if anyone can help it'd be greatly appreciated. thanks!


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post #2 of 14 Old 08-19-2009, 01:11 AM
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post #3 of 14 Old 08-19-2009, 01:59 AM
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What I did is as our corral member millhouse suggested and it work for me. take bov out then cut coil at a time. start car and let it idle , if you can push bov valve with finger easy then it good. If it's still stiff then you need to cut coil one at a time until you push valve easy with one finger. At first I push with my thumb and was easy but still stiff so make sure you push with like index finger. Cut springs coil at a time, wear eye protection , hand gloves e.t.c as I forgot to put gloves and with angle gringer I grind some meat of my thumb . You don't want to smell your own meat burning , disgusting and super painful . Hope this helps

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post #4 of 14 Old 08-19-2009, 09:02 AM
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Here is what happens when you touch an angle grinder with a cut-off wheel on it to your thumb for a millisecond…and yes, it hurt just a lil bit.




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post #5 of 14 Old 08-19-2009, 10:56 AM
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Dude Millhouse that is some scary looking sh*t . Wow mine was nothing that bad.

Voodoo racing innovation built 4v , powerglide, borg warner s475 at 29psi, custome turbo kit , pro efi ecu, Aeromotive fuel pump, aeromotive fuel rails, id 1000 injectors, e85. Best to date 1.36 60'
Best pass to date 8.92 at 156mph. Best 1/8 mile 5.6at 127 mph.
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post #6 of 14 Old 08-19-2009, 11:22 AM
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Dude Millhouse that is some scary looking sh*t . Wow mine was nothing that bad.
Yeah...and that happend AFTER I had told you about my previous encounter. Good times!
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post #7 of 14 Old 08-19-2009, 12:06 PM
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dont they make BOV that are adjustable? so that you dont have to cut down the spring?

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post #8 of 14 Old 08-19-2009, 12:44 PM
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they do, but not all

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post #9 of 14 Old 08-20-2009, 10:58 PM Thread Starter
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so just to clarify its okay to start the car and let it run with the blow off valve not bolted to the cold side, but still connected to vacuum so i can try to compress the valve with my finger? i figure its the only way to reach it but i just want to be sure, thanks

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post #10 of 14 Old 08-20-2009, 11:54 PM
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Quote:
Originally Posted by Splyt2nd View Post
so just to clarify its okay to start the car and let it run with the blow off valve not bolted to the cold side, but still connected to vacuum so i can try to compress the valve with my finger? i figure its the only way to reach it but i just want to be sure, thanks
Yes you can.


Voodoo racing innovation built 4v , powerglide, borg warner s475 at 29psi, custome turbo kit , pro efi ecu, Aeromotive fuel pump, aeromotive fuel rails, id 1000 injectors, e85. Best to date 1.36 60'
Best pass to date 8.92 at 156mph. Best 1/8 mile 5.6at 127 mph.
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post #11 of 14 Old 08-21-2009, 12:18 AM
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also if you have the $40 chinese knock-off BOV you have to take out the outer spring as it has two from the "factory" (wherever that might be)
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post #12 of 14 Old 08-24-2009, 07:47 AM Thread Starter
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well my blowoff valve came with a stiff spring installed and a softer one in the box, i swapped in the softer one and tried the finger test with the valve off the pipe but still connected to vacuum with the car on and it was near impossible to compress the spring- looks like ive gotta cut the spring back a little so this thing can open easier ya?

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post #13 of 14 Old 08-24-2009, 09:39 AM
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You can use a Mityvac with vacuum gauge connected to the source nipple. This way you can determine exactly how much pressure differential is needed to open the valve.

Also check your manifold pressure source line that it's not losing effectiveness because of collapsed line or wrong size line/splitter, etc.
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post #14 of 14 Old 08-25-2009, 05:39 PM Thread Starter
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well i cut a little off of the spring and nothing has changed. the valve is a little not too hard to open when the car is off, however when its on its damn near impossible.

i did T my boost gauge into the blowoff valve line and the boost gauge had a smaller vac line, i wonder if that is the culprit? other than that i have no idea...

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