Not good to much stretch - Southern Airboat Picture Gallery

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Not good to much stretch

These are a new set of ARP rod bolts they are the upgraded ARP 2000 bolts. The rod manufacture suggested 65ft lb's well they stretched almost twice whats acceptable. Most of our applications call for .005 to .0068 bolt stretch. After I replaced them I torqued the new ones to 55ft lb's to obtain the desired .005 of bolt stretch.

Waterthunder

Site Supporter - VIII

Registered: January 2005
Posts: 7,102

Date: Tue November 29, 2011
Views: 668
Filesize: 105.9kb, 148.5kb
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Keywords: not good to much stretch

nomad41
Site Supporter - V

Dave do you see this happening often?

#1 Tue November 29, 2011 9:55pm

air-roberts
Site Supporter - IV

yes it happens there stretch bolts which personally i don't like but yea after dave puts good bolts in them there not stretch bolts no more which is a must for demand use motor such as a airboat

#2 Tue November 29, 2011 11:02pm

Ruagatr
Site Supporter - VIII

Thats the difference between an engine builder and an engine assembler. The real guys measure stretch, not torque. Maddog

#3 Tue November 29, 2011 11:52pm

HuntingBigun
Site Supporter - VIII

#4 Wed November 30, 2011 12:42am

Waterthunder
Site Supporter - VIII

I was shocked they were the new and upgraded ARP 2000 bolts. I torqued them to what the rod manufacture suggested and it was too much. This is another reason we always use 40wt oil we have found with the assembly lubes and high pressure grease the torque numbers very TOO MUCH! I have used a torque wrench and a stretch gauge with several lubes and oils just to have an experiment on variances what I found changed the way we torque rod bolts.

#5 Wed November 30, 2011 3:56pm

air-roberts
Site Supporter - IV

yea if you look at the instructions on arp bolts it gives you one torq speck if you use there bolt lube and a different torq speck if you use oil. thats what i call being precise. thats the difference between as ruagatr said and durability. my old boat motor is 15 yrs old and believe me i did take a little break but in the beginning believe me i put hr's (hard) and countless bottles of nos and it still keeps up with most race-ride boats right now but i'm fixing to rebuiled it as soon as my new one hits the water

#6 Thu December 1, 2011 11:27am