ARP rod bolt upgrade

[steve cowan]

hey guys,
I have a set of 5.7'' scat H -beam conrods that have 8740 x 1.6'' long bolt i have used in a couple of 383sbc before
i am going to get them crack tested,resized with new bolts
can i upgrade to a ARP 2000 bolt?
will the extra clamping load on the conrod be an issue ? what i mean by that question is -
a conrod with a 8740 bolt designed for that bolt only with that clamping force 0.005'' stretch
ARP 2000 bolt 0.006'' stretch means more clamping force on the bigend of the conrod
sorry if i am not explaining correctly
or should i just stay with the 8740 bolt
application
383 sbc
looking for 550hp
i have a comp solid roller std base circle that does fit with these H -beam rods
262-270 @ 0.050''
680 lift with 1.6 jesel shaft system
106 LSA will go in at 102 ICL as a starting point
scat and JE rotating
as cast dart 215 pro 1s
exledyne valves
PSI springs 230 - 600
jesel 1.6 sportsman shaft
beltdrive
4 bolt 010 block
3500 pound car on 255 radial goes 11.10 @ 121 .56
at a guess motor makes 510hp approx
have been using my comp nitrous cam with i beams
254-260
680 lift
112 LSA in at 106
small base circle
no spray just motor
this was the only small base circle cam i had so used it all of 2017,time to find a little more power if possble
heads are unported,that will be coming this year
looking for feedback on conrods please
i know the engine is a bit of a slacker but still learning
thanks

steve c

[KnightEngines]

7/16 or 3/8" bolts?

If 7/16 then 8740's are fine, if 3/8" then you probably want 2000's or even 625+

If you're buying bolts anyway even at 7/16" you may as well get the 2000's.

The 2000's from what I know are the same material as 8740's, just a higher/more refined grade so they can be pulled down closer to yield.

Distortion going from 8740 to 2000 will be very minimal, more likely the rods will be further out from use than due to a bolt change!

[modok]

I agree.

[SupStk]

ARP 2000s are an upgrade in Scat rods, so no worries about using them. I would check bigend sizing after installing those bolts.

[kimosabi]

7/16 8740 compared to 7/16 ARP 2000 bolts are very similar with a touch higher ksi on the 2000 bolt. The bigger difference though is the ARP 2000 material have better cycling load longevity. ARP calls it 2000 but it's AMS6304 low alloy heat resistant steel. 8740 is about the same as 4340.

Both materials are way way above OEM quality.

[steve cowan]

thanks guys
yes 7/16 bolt
these are the same rods i put up here on speedtalk a while back with the discoloured thread on one rod bolt,the rods came out of my 383,no bearing damage,just the discoloured bolt thread on one rod,i remeasured everything and could not find a problem,the rods were not out of round the bearings were fine went through all the rod bolts again cleaned,measured,stretch to specs,measured,disassembled,cleaned etc etc,could not find a problem only this one rod bolt colour on thread,so did not want to risk it,i bought a set of scat 5.7'' I-beam rods with 3/8 8740 bolt and then had to change to small base circle cam hence using N20 cam
anyway i have been turning this thing to 7500rpm on the gear shift for the last 12 months,it runs its quickest et when it goes above 7000rpm shift but might be pushing my luck with the i-beams

scat rod bolt 008.JPG

scat rod bolt 005.JPG

scat rod bolt 001.JPG