New Engine Builder Questions

[Rich76_911s]

Hey guys,

I'm rebuilding my 1987 3.3L engine.

I recently had a post asking about separating Rod Caps from the Rods here.

Safe rod cap removal

I've decided to switch tactics and instead of asking individual questions and filling the board with my rookie questions, I'd just start a thread with all the questions in one. I'm going to post the questions in RED so you can skip over my blabbering if so desired.

So now that I've got the method for separating the rod caps. I have a new question:

How much variety in tightening a rod bolts is unusual?

Boyt911sc (Tony) lent me his ARP stretch gauge and I am using that to measure stretch. And I am using my torque wrench in 10 lb increments to get to the final strech, unless I only need a small amount more stretch then I'll drop to a smaller 5 or 2.5lbs of torque.

I've read here that most find they require higher torque values to achieve the desired stretch. So far I've done 4 rod bolts and I've gotten the desired stretch at 35 ft/lbs (3x) and once at 45 ft/lbs. Which seems to be a much wider spread than I'd anticipate. 40 ft/lbs is the suggested number for my 9mm bolts.

Here is a photo with how I've done this:

[Trackrash]

I recently installed ARP rod bolts on my SC rebuild. They are 10mm BTW. I found that after torquing to the 50 lbft specified, that all my bolts had stretched to within spec.

The stretch should be a confirmation of the amount of tension on the bolt. If the bolt stretches more when torqued to the specified lbft, then the bolt is weak and defective. If it doesn't stretch the specified amount, there is a problem with the torque value. Meaning the threads have dirt or burs, or are improperly lubed.

It will be interesting to hear what others have to say about your specific question in red.

[Rich76_911s]

Thanks Gordon for the input. Your results are more inline with my expectations. Which is what gave me pause with my results.

I did clean then lube the threads and nut before installation.

The Carrera's and Turbo's used 9mm bolts and have a suggested torque value of 40 ft/lbs.

[boyt911sc]

Rich,

There is something wrong with your illustration (picture). The stretch value on the gauge is close to the theoretical value needed but why do you have gaps between cap and rod? Secondly, are you measuring the stretch as you install them on the crankshaft? The recommended torque for your stretch bolts is 40 ft-lb. The instruction that came along with the ARP bolts suggests in the absence of a stretch gauge is to simply torque the bolts (lubricated using the supplied lubricant) using a torque wrench.

The variations in stretch values using your torque wrench depends largely on the calibration of the wrench. Using a difference tool like mine would probably give a different stretch value at the same torque setting. Unless your torque wrench is calibrated @ ISO xxxx level ( don't remember since I'm retired for more than 10 years now), there would always be some lingering question.

Either go straight to 40 ft-lb. torque or do a pre-tigthening sequence of 35 ft-lb. and measure. Then re-torque to to spec. and measure again. Since I have done these a half dozen times, it is less stressful compared to my very first installation. You are over thinking this process. Do not forget to lubricate the bolts. You will be fine.

Tony

[Rich76_911s]

Thanks Tony.

Yes I am tightening them on the crankshaft. The illustration is just to show the non-stretched measurement. And the target for final stretch.

I guess my concern is that I am getting big variation using 1 torque wrench. If I was consistently getting stretch at 35 ft/lbs At least there would be some consistency. Unfortunately no my tool is not iso xxxx.

Certainly am guilty of overthinkkng things.

[gtc]

Most of mine (same rods and bolts) required about 45ft*lbs. Other people here have reported the same thing.

Sounds like you're using a click-type torque wrench... i would switch to an old-school beam-type when using the stretch gauge.

Also make sure you are greasing them liberally... friction can affect your torque readings quite a bit.

[Rich76_911s]

Thanks Graham. I'd feel a lot more comfortable if my results were matching yours.

[Rich76_911s]

So this may take the 2016 dumb question of the year, but I have a seal for the bottom of the case, and I can't figure out where it is supposed to go. I don't want to mate the case halves before I figure out where this is supposed to go.





I've put all these in place:
1. Oil pump seals 3 ontop and one on the bottom.
2. Flywheel Seal
3. Pulley Seal (goes inside #8 bearing)
4. #8 O-Ring
5. Intermediate shaft cover plate seal

[Trackrash]

Distributor shaft seal.

[Rawknees'Turbo]

Originally Posted by Rich76_911s

So this may take the 2016 dumb question of the year,

Not even close to a winner, Rich - do you ever look in the 911 Tech forum ("how to wash the car" and "how to remove a pin head size drip of tar off my Fuchs" type questions come to mind)?!?!

And yep to Rash's ID.

[Rich76_911s]

Thanks Gordon.

Rawkness, when I saw your post I was almost sure I was going to hear something about Paul and losing a special ring.

[Rawknees'Turbo]

^^^

Too big to be Paul's!!!