I have just installed some of the standard replacements and there was only 1 rod that had any change and it was only 1/2 thousandths out so if there is any worry- thats what I encountered.

 

Did you remove the pistons completely from the motor and check the bores after installing the rod bolts during pre-assembly?

Or did you use plasti-gauge with the rods still in the engine to determine the clearance?

Or, what did you do exactly?

Thanks

 

I am building an engine and the rods where mic'd before and after.

 

Sweet, good info to know.

What's the amount of deformation that's considered to still be within spec on the rod bores?

Also, did you go by the torque requirement on the rod bolts or did you go by stretch of the rod bolts?

 

I just went by ARPs torque recommendations. I think the tolerances is +/- 8/10ths.

 

Do they provide a coinciding bolt stretch spec to correlate their recommended TQ profile?

The reason I ask is b/c Jason99T/A reported this:

Another thing to point out is measuring the housing bore with the rods bolts streched to the required amount, not just torqued to spec. Having the ARP pro-series bolts torqued to 45lb-ft very, very rarely gets you within the recommend stretch for this particular bolt. On the motors I have built, this generally takes 55lb-ft or so. This number will vary based on the type/amount of lube used, condition of the threads, and the calibration of the torque wrench.


Referenced from said thread: https://ls1tech.com/forums/showthrea...&highlight=ARP Post #16

 

I can see that, I just torqued them down like most will do for reference and first hand information. I have been building engines for about 12 years and I have not used the rod stretch method although I personally believe it is more accurate. I mainly started out torque method because I didnt have a stretch guage but since then have been able to buy one just havent seen a reason to change- no failures.

 

I was by no means trying to insinuate that you were doing it wrong.

I was simply trying to ascertain:

• Does ARP also include a coinciding stretch to go along with their desired TQ recommendation, to serve as a backup to double check.
• To ascertain if you had also determine the stretch after you TQ'd them to see if they were congruent (assuming ARP provide you with the info to deduce that).

Text is very hard to interpret in the same manner as face-to-face conversation that's why I wanted to clarify my intentions so that you don't have to assume my position, tone, etc of the text I wrote.

Thanks.

 

Also, another question.

I see that you were doing the recommend TQ that most people that would be doing with the motor still in the car and measuring for rod end bore deformation, etc. However, what about this scenario, say you TQ it to the ARPs method and get no rod distortion, how do we know if the TQ that is provided is enough to prevent rod bolt failure (i.e. stretched too little or too much)?

Sorry for all the questions. I just like too know as much as I can.

 

I did not take it that way although like you said text messages can start wars lol. I did not measure stretch but ARP does include that info in its paper work.

 

Excellent. I'm glad they include that corresponding information with their TQ profiles, at least for those fasteners where stretch can be measured.

 

According to ARP they say that either method is fine to use but for accuracy the rod stretch is the way to go. Torque method will not cause failure, the main reason the stretch method exists is to take as much tolerances out of the equation like the torque wrench being out and different use of the wrench itself(different ways people pull on the wrench will change total torque slightly).

 

Thanks for all the info, Bo White. I appreciate it.

 

ARP says the desired stretch is .0055"

 

This is the info that the forum needs!

Thanks.