Rocker Shafts:Can I estimate 18 foot lbs with a 1/4 inch drive?

[IAN]

I 'm in the process of installing rocker shaft seals on my 72 911T.

I'm wondering if I can estimate the 18 lbs of torque required on the 5mm rocker shaft hex nuts. I'm using a stubby 5mm snap on hex socket on a 1/4 drive which fits really well. The 3/8 torque wrench I have has no chance of fitting.

I don't own (and would like to avoid owning right now) a 1/4 torque wrench. I've also noticed that most of the 1/4 torque wrenches only go to 200 inch pounds which is 16.6 foot pounds.

So I guess the real question is...

Is it possible to overtighten the rocker shafts with a 1/4 socket?

Thanks,
Ian

[walt]

Check out this recent thread. Go down about 5 posts to the response from Jims Sims, he explains how to use a larger wrench to do this. Help! My rocker arm shaft is falling out.

[Eagledriver]

I recommend using a "normal" allen wrench (about 3 or 4 inches long). Tighten it as hard as you can with this wrench. The spec of 18 lbs is not tight enough for a used cam tower. If you don't do this you may find rocker shafts "walking" out of the tower. With a 1/4 inch socket you may not need to pull quite as hard as the handle is smoother and won't bite into your had as much as the allen wrench will.

-Andy

[DonE]

I just rebuilt my 930 motor using 18ft lbs as the value to torque my rocker shafts. Since this is a Porsche spec, are you saying this is incorrect for a rebuild? This is news to me.

[jbrinkley]

you guys got me all nervous, in exactly 1300 miles I've had two shafts walk. # three and # two exhaust, respectively.
I removed and reinstalled, tightened with standard allen key just about as tight as I could by hand. Then I read last night on the other forum that you can deform the housing. Is that posible without using a allen/driver?
had bad dreams and couldn't sleep last night

[304065]

Check the competition engineering web site for a procedure on this, they go beyond the torque specified by the factory for no leaks

[Fishcop]

40 pounds is what has now been recommended to me by several people (yeah it's a bit scary). I used the RSR seals and 40 pounds... no leaks, no walking.

[jbrinkley]

thats nice to hear
I'm feeling a bit better
but 40 pounds, WOW

[TimT]

Hmmmm Im sure Ill take the wrath of the posters.

Ive built quite a few 911 engines

I always thought the rocker shaft bolt was one of those "feel" things.

I havent had many rocker leak problems

[john walker's workshop]

the book says 18 newtonmeters, not ftlb. that's a bit over 13ftlb. on used towers, the used shafts often walk out at that torque. 18-20 ftlb is recommended for used stuff. (not by porsche, by experienced techs). 40ftlb is asking for broken shafts (and bolts) that upon removal will gall the shaft bores. if you hear a snap, the shaft broke.

[aigel]

I fastened mine by hand also. The torque on these isn't really about the fastener being at it's optimum, rather than the press fit that results from the torque on the shafts themselves. So, overtorquing won't strip the nut. I went definitely higher than 18. 25 where I could read the torque, very snug elsewhere. I installed the RSR seals too. Dry so far, almost a year later. If you read Wayne's book, he recommends higher torque on leaky or old cam housings.

George