Decel Valve--vacuum limiter--install

boogie_man · 03-14-2009, 02:25 PM

Hi, I'm new to the board as I just purchased a very clean 1982 911SC Coupe. Upon going over it with the seller, he advised the decel valve was confirmed to be on it's way out (high idle when coming to a stop with clutch in, then slowly winds down). I was wondering if they're avail and the ease of install. Any input would be great and thanks for having me....this is my 2nd 911 (10 years ago 79 SC Targa).

Scott

SpeedracerIndy · 03-14-2009, 03:40 PM

Most people would say that the decel valve is not completely necessary. You can remove it and plug the lines and the car will run fine.

I happen to like the what it does. It makes rev matching easier by causing the engine to hang a bit when letting off the gas.

There are versions that are adjustable. Mine is, and I believe the earlier ones from 78-79 are on USA models. If yours is shaped sort of like a bell with a vacuum line coming out of the top, it is adjustable. Take off the vacuum line and unscrew the nipple to shorten the amount of time the engine hangs.

boogie_man · 03-14-2009, 05:34 PM

Hey thanks for the reply...any links or photos to make sure what/where I'm dealing with this ??? Might blocking it off to see if that's the fix. Or should I just put a new one on ?? Easy to get to ??? Again thanks

Gogar · 03-14-2009, 11:19 PM

Scott,

Once you find the decel valve: If it's hooked up, just pull the vacuum line off and plug the line with a golf tee, or a small pencil, or something. Then, see if your problem clears up. As already mentioned, many people unhook the decel valve on purpose.

If plugging the line works for you, make sure to take the line out and plug it with a vacuum plug where it meets the airbox.

On my '83, the decel valve is on the passenger side of the engine, slightly higher than the valve cover, towards the front of the engine. And yes, its unhooked.

kodioneill · kodioneill's Garage

The idle on my 82sc hung up also. it was the weights in the distributor hanging up. just another place for you to look in case it's not the valve.

Jim Williams · 03-15-2009, 05:41 AM

On your '82, the decel valve will be located in the area behind the fuel distributor (towards the front of the car). The Aux Air Valve and the Decel Valve will look similar, both being saucer shaped. The Decel Valve will be the one with three hoses, one small line and 2 larger ones. The line which controls the opening and closing of the diaphragm is the small one. Plug it and see what effect this has on the high idle.

arbita1 · arbita1's Garage

Quote:

Originally Posted by kodioneill

The idle on my 82sc hung up also. it was the weights in the distributor hanging up. just another place for you to look in case it's not the valve.

Could you explain this one a bit more.

kodioneill · kodioneill's Garage

my idle would hang above 1000 for a long time after warm up. i check all the warm up control components and everything was good. so i pulled my distributor and took it apart. the inside was covered with dirt and crap. cleaned everything assembled it and now it runs like a dream. search "sc dizzy" you'll find many posts on this, and some neat pics of the dis assembly process.

boogie_man · 03-15-2009, 08:01 AM

Golf tees are amazing !! LOL. it worked idles like a champ. Do i need to plug the top of the saucer at the nipple ?? Thanks for the advise.

Gogar · 03-15-2009, 08:14 AM

Quote:

Originally Posted by boogie_man

Golf tees are amazing !! LOL. it worked idles like a champ. Do i need to plug the top of the saucer at the nipple ?? Thanks for the advise.

NIce! Don't think you need to plug the 'saucer', but remove the vacuum line and plug the nipple you expose on the airbox when you remove the line.

If you have an extra vacuum plug, probably won't hurt to put it on the nipple on the "saucer" as well, just in case, to keep it from getting all dirty.