what does it do? and do you recomend it?

 

this is basicaly a spring loaded check valve . it consists of a hole being drilled in your plastic intake that the device is placed in. CIS engines are very sensitive to starting mixture and if it is not perfect you can have a backfire in your intake. the pop off valve allows this backfire pressure to escape, instead of blowing up your air box.
Air box replacement is not cheap , even as a DIY job it can be involved. There are some who believe it as absolute must in CIS cars, and there are others who believe a car in good tune does not need one and the pop off valves themselves can cause problems by not seating properly and letting unmetered air entering the engine.
I think those people who have suffered a blown air box , put one in the replacement. I must add that I have had my car for 3 years and the pop off valve is still sitting on my shelf in a bag. My engine runs really well and I have never felt a need to put it in . I am sure others will chime in with their opinions.


ice

 

I got one and installed it before I attempted to start my car for the first time in 14 years. I had no idea where the idle or mixture were set so I thought of it as cheap insurance.


Yes, it did backfire a couple of times before i got the fuel system sorted out.

 

I have a new spare one for sale if you want it. $25 shipped. PM me

 

Ice

With all the issues you have had with belts, etc. I would install a minimun of four in your air box!!!

Ernie 81SC

 

no kidding Ernie .. and now I am out of ammo ( no belts left ) I need to stock up ... hey i should have Vendors send me belts and I will do a stress test .. see how they stand up to oil caps, missed shifts, oil rags etc..

I really need to fire my mechanic .. but I just don't have the heart to do it .. he takes those things kind of personally. I think myself lucky I don't have Ac and a smog pump . all those belts would cost me a fortune..

 

Iceman,

Maybe you should change your user name to "Beltman"

John

 

...how about "frostbelt?"

 

I had one of these and would recommend it. I think it saved me once or twice. BUt they are not infallible...I blew an airbox a month after installing one of these valves. So they help but are not 100% guaranteed to work.

 

yes!

ask me how i know

 

I always thought this thread is one of the mandatory reads from Mr. Zimmerman. Pete, I hope you don't mind me bringing up this thread again.

To Pop Off or Not

Pete's been so dead on with advice over the years that I'd take this tread pretty seriously.

Jay
90 964, 84 3.2

 

Hey Pete! I've got the first edition of your book (not handy to me at the moment) that came with my SC. Great book!

But.....re pop-off valves: didn't you kinda' pooh-pooh them and say that, no matter what, in time your air-box will explode?

 

Jay - you posted this while I was typing. Probably answers my question but your link doesn't work for me.

 

Sorry! The link is now fixed.

 

Yup - that's what I was recalling reading. Mine came w/pop-off, mech. checked it and said it's operational. I keep the motor tuned and it ain't fired back at me yet .