Rod bolts, OEM vs Porsche vs ARP?

[kav]

I'm ordering a set of new rod bolts for my 1969 911T and was wondering which ones to order?

There are the OEM version part No: 901-103-172-00-M260 which are $138 for the set.
The genuine Porsche part No: 901-103-172-00-OEM $246 for the set.
And I found these ARP rod bolts for $224 a set.

The Official ARP Web Site | Kits

I'm not sure these are the correct bolts for my 1969 911T? I've heard good things about the ARP bolts (you can reuse them etc) and the price is cheaper than the Porsche.

Any advise,

Cheers.

-Kav.

[DRACO A5OG]

+1 ARP is what most will use no need to pay the Porsche tax.

[gtc]

You can get those ARPs on amazon for $163.

[kav]

Thanks for that! I just ordered a set from Amazon, hopefully they'll be the right size!

Cheers!

-Kav.

[kav]

The ARP rod bolts arrived today. As you can see from the picture below they are the same length and from what I can tell without breaking the packaging (I may not be able to return them if I open them?) the same diameter but I have some newbie questions:

The original rod bolts have a lobe near the head of the bolt while the ARP's do not, should I be worried about that?

The ARP's have their own 12 point nuts but the skirt of the nut looks very wide?

There seems to be a huge debate on the use of thread locker on the rod bolts?

I should buy a stretch gauge and measure the stretch over the torque?



Cheers!

-Kav.

[Tippy]

I don't think thread locker is needed, but a rod stretch gauge is a must.

Torque is all over the place due to friction and other factors.

[Rusty 356]

We are in the process of installiing a set for a 996. Use ARP lubricant and we purcurchased the ARP stretch gauge from PitStop USA. Pretty good discount. Gauge is easy to use, but required a bit of effort with an extension on a box end wrench. ARP is nut is not metric so a good 12point is needed.
good luck. Also, PitStop have some need engine building measuring tools at what i consider reasonable.

[gtc]

Originally Posted by kav

The original rod bolts have a lobe near the head of the bolt while the ARP's do not, should I be worried about that? No.

The ARP's have their own 12 point nuts but the skirt of the nut looks very wide?

There seems to be a huge debate on the use of thread locker on the rod bolts? Use a liberal amount of ARP assembly lube on the threads and on the face of the nut.

I should buy a stretch gauge and measure the stretch over the torque? Yes.

Include the ARP rod bolts when you send out your rods to be resized.

[KTL]

Use a torque wrench to tighten them as you're measuring stretch. Sounds stupid, I know. But here's why I suggest that.

1. You can compare how much ultimate torque you have to apply to reach the recommended stretch amount, versus just tightening them to the recommended torque and calling it good.

2. You can catch a bad bolt by using the torque wrench. In other words, if you use a plain box wrench? You have no idea how much torque you had to apply to reach desired stretch amount. But if you're using a torque wrench and you find it only took 30 ft-lbs to reach the desired stretch, the bolt is faulty.

#2 sounds stupid/unlikely but i've seen a friend experience it with one bolt when building a 911 engine with ARP rod bolts. Better to be safe than sorry.

ARP Rod bolt won't torque!

[kav]

Originally Posted by gtc

Include the ARP rod bolts when you send out your rods to be resized.

The rods are already back from the machine shop so I will have to rip and tear into the ARP packaging unless the differences are glaringly wrong between the two bolts?

[kav]

Originally Posted by KTL

Use a torque wrench to tighten them as you're measuring stretch. Sounds stupid, I know. But here's why I suggest that.

1. You can compare how much ultimate torque you have to apply to reach the recommended stretch amount, versus just tightening them to the recommended torque and calling it good.

2. You can catch a bad bolt by using the torque wrench. In other words, if you use a plain box wrench? You have no idea how much torque you had to apply to reach desired stretch amount. But if you're using a torque wrench and you find it only took 30 ft-lbs to reach the desired stretch, the bolt is faulty.

#2 sounds stupid/unlikely but i've seen a friend experience it with one bolt when building a 911 engine with ARP rod bolts. Better to be safe than sorry.

ARP Rod bolt won't torque!

That makes sense, I will follow those suggestions. Thanks!

-Kav.

[kav]

Originally Posted by Rusty 356

We are in the process of installiing a set for a 996. Use ARP lubricant and we purcurchased the ARP stretch gauge from PitStop USA. Pretty good discount. Gauge is easy to use, but required a bit of effort with an extension on a box end wrench. ARP is nut is not metric so a good 12point is needed.
good luck. Also, PitStop have some need engine building measuring tools at what i consider reasonable.

I will order the ARP stretch gauge from PitStop USA and buy a good 12 point socket.

Thanks!

-Kav.

[Tippy]

Just use a standard box end wrench for stretch gauge

[gtc]

I used a torque adapter and a beam style torque wrench when using the stretch gauge. Definitely needed another set of hands to hold everything when doing the plastigauge.

[racing97]

You can use one of the digital torque wrenchs with the torque adapter and set the offset in the readout so that you can observe the feature during stretch that the bolt manufacturer specifies in the "not to exceed 65 lbft", with this you have everything covered.

regards

[Jeff Alton]

Originally Posted by KTL

Use a torque wrench to tighten them as you're measuring stretch. Sounds stupid, I know. But here's why I suggest that.

1. You can compare how much ultimate torque you have to apply to reach the recommended stretch amount, versus just tightening them to the recommended torque and calling it good.

2. You can catch a bad bolt by using the torque wrench. In other words, if you use a plain box wrench? You have no idea how much torque you had to apply to reach desired stretch amount. But if you're using a torque wrench and you find it only took 30 ft-lbs to reach the desired stretch, the bolt is faulty.

#2 sounds stupid/unlikely but i've seen a friend experience it with one bolt when building a 911 engine with ARP rod bolts. Better to be safe than sorry.

ARP Rod bolt won't torque!

Great advice, but you must ensure repeatability with the gauge. Test a few bolts at rest with your gauge set up to ensure this. We had 3 gauges we used. ARP and 2 other brands purchased at our local hot rod expert retailer. We now only use the ARP gauge and gave away the other 2. It was the only one where we could get repeatability.

Not important if you use a box end wrench as the gauge stays on the bolt, but if you are using a torque wrench where removing the gauge is required, then the ARP one worked the best for us.

Cheers

[gtc]

Even with the ARP gauge I found it difficult to get a repeatable measurement, hence my torque adapter setup which didn't require removing the gauge from the bolt.

[KTL]

Jeff,

I agree repeatability is a must. That requires good technique/attentiveness and also a quality dial indicator. I also recommend guys use a pointed attachment on the indicator plunger. The typical roller tip that most indicators are equipped with doesn't fit into the dimples in the bolt.

Totally agree some of the speed shop stretch gauges are sketchy and IMO that's because of the crappy, cheap indicator most come with. I bought an inexpensive stretch gauge and the frame itself is nicely constructed. But the gauge might as well be given to my little 3 yr. old to entertain him as a "clock"

[Tippy]

Hmmm, the one I used was very smooth and repeatable. Not sure brand.

[Ken911]

Red Loctite every time, if you miss a shift and over rev it the rod bolts usually yield before breaking. if the nut is loctited it will stay together unless the bolt is broken and not grenade the whole engine with no Loctite the nut will just spin off once the bolt has stretched and then destroy everything. The rod bolts are still easy to take apart the next time if ever needed,