CIS Pop-Off Valve
Racer
Joined: Jun 2016
Posts: 303
Likes: 0
From: CT
Unfortunately, I know nothing of what the original owner of my SC has done, other than what I can see, and I can tell they definitely cared very much for the car.
I do know that the second owner prior to myself, and his mechanic was trying to sort out a backfire issue and were exhausting a lot of time, when they found out that the "Airbox itself was defective". The Airbox was replaced with a new one from the factory, and a pop-off valve was installed as well.... Maybe overkill, but hey, at least I bought the car after that bit was sorted...
-Cam
I do know that the second owner prior to myself, and his mechanic was trying to sort out a backfire issue and were exhausting a lot of time, when they found out that the "Airbox itself was defective". The Airbox was replaced with a new one from the factory, and a pop-off valve was installed as well.... Maybe overkill, but hey, at least I bought the car after that bit was sorted...
-Cam
Last edited by 09mageec; Jul 18, 2017 at 12:00 PM.
Instructor
Joined: Jan 2008
Posts: 220
Likes: 5
Thanks for the warning. Just wondering a couple things. Do you remember what sort of epoxy you used? And, secondly, how time consuming was the chain tensioner repair (leaving out the reverse distributer installation "modification")? I plan on updating my mechanical tensioners with an oil fed conversion update when the weather cools a bit.
Team Owner
Joined: Aug 2005
Posts: 28,495
Likes: 1,636
From: Cambridge Ontario Canada
Hi. Yes, I know the pluses and minuses of relying on a pop up valve in my 1976 911 S. I have been tuning it since 1982 and would really prefer not to rely on it in case of back fires but given the fact that it is now a rarely used car I am always fearful on the first start up of the season. It is difficult to get it running without a backfire or two. I have just replaced my box for the first time and would like it to last. My question is what type or brand or name of epoxy does anyone suggest when installing this? Any suggestions would be appreciated. I may be back for advice and or cautions to help with updating the chain tensioners. I have been putting for some time and plan on attacking it this fall. I only have 70K miles but would hate to trash the engine should the chain skip or worse. (Actually, my main concern in this repair is that I will destroy the muffler which is also original.)
I think what you may be asking about is oil fed tensioners used on the Carrera, many people do go to these and its a pretty good upgrade , I think many do the upgrade and its not necessary but to each his own.
I think you also have the ability ( and do it if you can ) to go to a wider idler arm for the tensioner sprocket. the older version is a narrow arm with a spacer. I replaced mine with the much beefier wider arm.
Also you can put a spacer INSIDE the pressure fed tensioners that again will prevent total collapse and catastrophic failure.
in the pics you can see the silver spacer. stupid me forgot to take a pic with the new style in there but just imagine the idler arm being fatter and not needing the spacer.
3rd Gear
Joined: Jul 2017
Posts: 3
Likes: 0
Thanks all for the replies. I had thought about the safety collars but figured once I went through all the effort of draining the oil and opening it up I might as well bite the bullet and do the tensioner upgrade. I have the wintertime to work on it. I also plan to replace the cold start valve that has an intermittent issue as well as either rebuild or replace the fuel distributor. I understand that the original gaskets/seals are prone to failure with the new gas/ethanol mixtures. (I have had this issue with fuel systems in a number of my older cars.) And thank you Iceman for the suggestions and the photos. I will also document my repairs and foibles as well as post photos should I proceed.
