Valve Adjustment - retaining nut
08-30-2005, 11:46 AM
#1
Pro
Thread Starter
Valve Adjustment - retaining nut
Getting ready to tackle a valve adjustment this weekend for the first time. I've read several articles, have the 101 Projects book, etc. I've also searched the archives looking for an answer to no avail. Here's the question plus a couple more.
After you loosen the retaining nut to turn the screw to adjust the valve, how tight should you re-tighten the retaining nut? I suspect that if you put too much torque on it, it will turn the screw as well, making it too tight to remove the blade. However if it is not tight enough, I assume the nut can start to back off, allowing the screw to back off becoming loose and making the clearance too wide.
If you slide in the blade and it is snug, do you still re-adjust, or do you leave it and move to the next valve?
Other than checking the headstuds, is there anything else I should check while I'm there?
TIA you guys!
Regards,
Jim
'86 Carrera Coupe
After you loosen the retaining nut to turn the screw to adjust the valve, how tight should you re-tighten the retaining nut? I suspect that if you put too much torque on it, it will turn the screw as well, making it too tight to remove the blade. However if it is not tight enough, I assume the nut can start to back off, allowing the screw to back off becoming loose and making the clearance too wide.
If you slide in the blade and it is snug, do you still re-adjust, or do you leave it and move to the next valve?
Other than checking the headstuds, is there anything else I should check while I'm there?
TIA you guys!
Regards,
Jim
'86 Carrera Coupe
Last edited by jet911; 08-30-2005 at 12:23 PM.
08-30-2005, 12:06 PM
#2
"how tight should you re-tighten the retaining nut?" Good question!
I am sure there is an official Porsche torque number, but I have never used a torque wrench in my many years of adjusting 911 valves. I just get the nut good and snug; in other words, it will take a little tug to break it loose.
When you tighten the retaining nut, the adjusting screw will turn. I usually try to hold the adjusting screw in place with a stubby screw driver while turning the retaining nut. I also leave the feeler guage in place while tightening the retaining nut.
I do not re-adjust valves that are properly adjusted when I first check them...YMMV. When I do my annual valve adjustmets on my two 911's, I usually find that only half of the valves need to be re-adjusted...the others are OK.
I am sure there is an official Porsche torque number, but I have never used a torque wrench in my many years of adjusting 911 valves. I just get the nut good and snug; in other words, it will take a little tug to break it loose.
When you tighten the retaining nut, the adjusting screw will turn. I usually try to hold the adjusting screw in place with a stubby screw driver while turning the retaining nut. I also leave the feeler guage in place while tightening the retaining nut.
I do not re-adjust valves that are properly adjusted when I first check them...YMMV. When I do my annual valve adjustmets on my two 911's, I usually find that only half of the valves need to be re-adjusted...the others are OK.
08-30-2005, 01:09 PM
#4
Rennlist Member
Bruce's tips are right on. You should never overtighten a jamb nut in order to reduce clearance, the nut should always be loosened so the screw adjuster may be turned. Then, when you snug the jamb nut, always hold the adjuster with a good quality stubby screwdriver. Regarding how tight, again, Bruce has it right - snug is snug, the nut won't go anywhere. Here's an exercise for you: Put an 8mm hex-head bolt in your vise, have it sticking straight up. Put something over the threads leaving a nut thinkness or so of threads sticking out. Install a wavy lock washer and a nut in good condition. Snug that nut down by hand, with the wrench you will use for your project, until you think it's snug enough. Now put a torque wrench on the nut, set to 18 lbs, and check your work. Was it too loose? I doubt it. Was it too tight? It wouldn't surprise me! Educate your wrist to learn what 18 ft/lb feels like. Now, after you have your valve adjusted, you've removed your gauge with some drag against it, and you're able to put it back in, you're done. At this point I always put the stubby screwdriver back on the adjuster and give the jamb nut one final application of torque (99% of the time not even hard enough to move the nut, basically just to be sure that I already tightened it), and when I pull the gauge out I make sure nothing has changed.
Hopefully you're changing the oil also, take the oil out of the engine before you take off the lower covers, you'll have a much smaller mess. Putting a cut-open large cardboard box under each lower cover before you remove it does wonders for your floor. Also, working behind the cat, 1,2 and 3 exhaust valves, is a little tricky. The best thing to make your job easier is to have enough shim stock on hand so when a piece gets kinked or scratched you can replace it before moving on. Have fun with it!
Pete
Hopefully you're changing the oil also, take the oil out of the engine before you take off the lower covers, you'll have a much smaller mess. Putting a cut-open large cardboard box under each lower cover before you remove it does wonders for your floor. Also, working behind the cat, 1,2 and 3 exhaust valves, is a little tricky. The best thing to make your job easier is to have enough shim stock on hand so when a piece gets kinked or scratched you can replace it before moving on. Have fun with it!
Pete
08-30-2005, 01:34 PM
#5
Rennlist Member
Jim: One more thought, I use Stahwille wrenches, which have a very shallow broach before the teeth start. SnapOn wrenches are similar, but because the jamb nuts are very thin if you're working with Craftsmen, etc., you might want to grind away some material before you start. You always want to work with the box end, there is too much of a chance to slip and ruin a nut with the open end. Look at the box end of your favorite 13mm wrench, if it's cut too deep before the teeth start hold the side that will go onto the nut flat against the side of your grinding wheel and try to reduce the tapered depth to the teeth to less than a millimeter. That should make the job go a little easier.
Pete
Pete
