I just make a TID mod for my 87 TII and couldn't find a proper checkvalve for the stock BOV to be open atmosphere. I blew out a brake booster C/V and found a PCV C/V didn't seal well and was way too restrictive. Right now I have one made out of the neck of a thick plastic bottle and a similarly shaped rubber disc held against it w/ elastic. Works great, but of course I want something more permanant! Oh, what a difference by the way. Fast spooling, a bit more boost and great whooshing sounds. TID mod is the sh....

 

Easy... go to you local Home Depot and hit up the Plumbing section. There you will see a spring loaded check valve. I saw them there the other day. If you don't see it let me know. I'll dig mine up and snap a digi pic.

 

Here's a picture (sorry it took so long) of the spring loaded check valve and stock bov...



Good Luck!

 

Damn thats big...Thank you so much for the pic! If there is one around here I should have no prob. finding it now.

 

Haha, that's the same one I bought last night at home Depot..
I was looking at the larger 1.25 inch one, however in conversation with Chris NG he had some reservations about the larger valve having a stronger spring.
I may return the one inch check valve and get the larger one and try changine the spring in the 1.25" one to a lighter spring, I am also thinking of cutting the valve in half to get rid of the threaded outlet and a good chunk of wieght in brass hanging off the blow off valve.
Anyone using the DSM blow off valve??
Max

 

I wouldn't worry about the spring tension being too strong. When I compared the spring pressure to my Turbo XS Type H spring the Home Depot one is nothing. Oh, and don't expect that one to go WHOOSH!! It flutters. Some say it sounds like some older HKS BOV's. I have a Saab BOV that is really loud that I could've attached to it but never got around to it.

Oh and if you look real close you can tell it is a T-spec valve

 

Unfortunately Spring tension does matter..
Your spring tension might be loose enough to allow 10 psi of boost to bleed off. but what about 5 psi? 3 psi? .. if it can't overcome the spring tension It's just going to head back towards your compressor ..

You can't really compare the check valve to the design of an actual BOV either.. you may have higher tension on the BOV plate, however you also have vacum to open it.. Really, the thing to look for in check valve is enough tension to keep the checkvalve from fluttering when driving close to positive pressure but make enough of a good seal to prevent a vacume leak...

I betcha if you wrap your lips around the nipple on your BOV and suck on it the plate will open with relative ease.. even if the spring tension used to keep the plate closed is higher then the checkvalves..

By the way.. you have the checkvalve on the wrong end of your BOV .. I'm willing to bet that you are bleeding boost out the checkvalve which is causing you to thing that it makes a fluttering sound (cause it doesn't)