ARP rod bolts on 3.2L

[CruiseControl]

The machinist has the crank, rods, rod bolts, bearings etc and is at the stage of confirming big end bearing sizing.

With the ARP rod bolts could some one confirm the following steps are OK.
Measure length of each "virgin" rod bolt and note the bolt and length.
Machinist to use the torque method (35ft/lb) for the 9mm bolts, for the sizing checks of the big end, bearing and crank.
In final assembly of rods to crank use the stretch method (0.012" stretch from the "virgin" length) for each bolt, firming each pair to 5ft/lb then to final length in one step for each bolt.

Reason for asking question is machinist does not have stretch gauge, and as I am out of town for next week can not provide my stretch gauge to machinist.

Thanks in anticipation.

Paul

[Determined]

Paul,

I was in an identical situation as you just weeks ago, this past weekend I mounted my 3.2 rods with ARP rod bolts. My machinist used my old rod bolts and torqued them down to specification, I believe my Bentley manual calls out two stages. First is 14 ft lbs then Second is 90 +/- 2 degrees. My machinist reconditioned both ends of my rods and I balanced them myself within .12 grams of each other. You can do a search under my user name to see some similar topics and data I presented.

During actual mounting to my crank, I used the stretch gage approach...much...much better and I feel more confident now. I also pre-tightened my bolts to about 5 ft lbs then performed my stretch. My rods specified between .0117 and .0122. Without the stretch gage I don't know how anyone would feel they did it right. Good luck!

Best Regards,

Alex

[ChrisBennet]

You don't need a stretch gauge. I just use a micrometer.
-Chris

[MBEngineering]

HI print off the rod bolt sheet from the ARP site and note all the bolt sizes on it and then you can use them again by checking the stretched size as the instruction in the packet. if you do not know the original size , you will not know the stretched length and limit to take the bolts to. www.arp-bolts.com
http://www.arp-bolts.com/Tech/T1_InstallPages/T1_Images/RodBoltStretchChart.pdf
regards mike

[CruiseControl]

Thanks Alex, Chris and Mike for your replies.
Mike, I measured all bolt lengths, and identified each bolt, prior to handing to machinist.

As the machinist does not have a stretch gauge, could he use the old rod bolts for sizing the big end bearings?

I would then use stretch method with ARP bolts on final assembly.

Chris, I feel that the location indents on the bolts provide a more precise positioning for the measurement instrument, hence feel a whole lot better using the stretch gauge with the "V" locators than the flat micrometer for measurement bolt stretch.

Again, why can not the original bolts be used by the machinist, and just torqued to spec for machining checks? I do not understand the why it is necessary to use the new bolts at this stage of the process.

Thanks
Paul

[MBEngineering]

HI Paul if you have the old rod bolts , then I would send them for the re-sizing of the rods , as you are only clamping the rod together for machining. JUST make shure the bolts are not left to be used again and scraped as they are removed from the rods.

regards mike

[ChrisBennet]

Originally posted by CruiseControl
Chris, I feel that the location indents on the bolts provide a more precise positioning for the measurement instrument, hence feel a whole lot better using the stretch gauge with the "V" locators than the flat micrometer for measurement bolt stretch.

Whenever there is a concern about the measurement techique one simply tests that multiple measurements of the same item are repeatable. I've found "mike-ing" ARP and Raceware rod bolts them to be accurate and repeatable.
-Chris

[CruiseControl]

Mike, your above comment is exactly what I wanted to hear, and provides the understanding.

Chris, yes I agree with repeating to check measurements, when "mike-ing", however the stretch gauge sitting "snug" in the "V" dibbits of the rod bolts just feels better. Then again taking your advise on repeat measurements, and do a further "mike-ing" at the end as a further confirmation would not be a wasted 15 minutes.

Alex, checked the other threads and appreciate you assistance.

It will be the end of next week before I am back in home town, hopefully machinist will have parts ready to commence assembly.

Thanks again to you all -
Paul