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Aftermarket rod torqueing

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Discussion starter · #3 ·
I dont have a sheet. These rods were used in the motor from the last build, and I had some one else build it that time and now we no longer speek that much. Because he has had my block for 8 months waiting on him to install cam bearings and never did. When I went to pick it up, It looked like it was left in the rain for a month.

So now I am kinda stuck :confused: The rods are Scat 4340 I beams with screw caps. And I cant figure out the bolt size :dead: The thread and collar under the bolt head is 7/16 and in between is 3/8. I hope this helps.

Thanks
 
Discussion starter · #8 ·
On ARP site they showed my bolt size to be torqued at 90 with 30wt oil and70 with the ARP lube.

Scat shows them to be torqued at 63 with the arp lube.


Thay are ARP 8740 Scat -01. That what is etched on the top
 
Discussion starter · #9 ·
This is from Scat website:

5/16" x 1.500" ARP 2000 cap screw 26 ft./lb w/ARP moly (.0056" stretch)

3/8" x 1.600" ARP 8740 cap screw 45 ft./lb w/ARP moly (.0047" stretch)

3/8" x 1.600" ARP 2000 cap screw 50 ft./lb w/ARP moly (.0058" stretch)

3/8" ARP 8740 Wave Loc bolt & nut 50 ft./lb w/ARP moly
(.0063" stretch)

7/16" x 1.400" ARP 8740 cap screw 64 ft./lb w/ARP moly (.0046" stretch)

7/16" x 1.500" SCAT 2001 cap screw 63 ft./lb w/ARP moly (.0050" stretch)

7/16" x 1.600" ARP 8740 cap screw 63 ft./lb w/ARP moly
(.0050" stretch)

7/16" x 1.600" ARP 2000 cap screw 70 ft./lb w/ARP moly (.0062" stretch)

7/16" x 1.800" ARP 8740 cap screw 63 ft./lb w/ARP moly (.0060" stretch)

7/16" x 1.800" SCAT 2001 cap screw 63 ft./lb w/ARP moly
(.0060" stretch)
 
#11 ·
Scat should not give you a different Tq number than ARP does for the same bolt. Stretch of the bolt is what you are going for here, not anything else. An ARP bolt with the same lube/Tq is going to stretch the same no matter whos rod its used in.
 
#16 ·
23chaparral said:
There are actually 3 but I only showed 2. According to Scat's web site the one's that are used in mine a in the 200,000 range
Click to expand...
Their regular bolts, and their wav lock bolts are 8740. Their "pro series bolts" are called "ARP2000", what ever that material must be.

ARP's web site is not the most user friendly in the world. Also note that the Tq spec page they show where you got the 90 lbs from is a general info page, and NOT for a specific bolt.

Tq and not stretch is fine. I'd call ARP on Monday and see what they tell you. You want to be 100% correct with rod bolts.
 
#19 ·
The proper way to torque the bolts is with a dial indicator to measure stretch. Since these bolts have been "torqued to spec" with the last rebuild, the accuracy will probably be off. Spend the money and get the proper tool unless you're not concerned about your investment.

Powerhouse, Summit and Jeg's sell the tool. I think the ARP tool is about $150 (and it includes a dial indicator that you can use for other stuff).

PLEASE!! Follow this advice.
 
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TomZ
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