Reusing Rod Bolts??
02-01-2017, 10:05 AM
#21
Melting Slicks
The engine shops here say that when a rod bolt is installed it is a a slight interference fit in the bolt hole which likely will slightly distort the big end hole. When rod bolts are installed they are torqued to 95% and the big end hole is re-sized. They are adamant on this. Race engine guys believe that rod bolts can only be re-torqued 2-3 times before changing bolts and re-sizing. High end guys measure bolt stretch instead of torquing. I believe that if you have removed a bolt, you will need to resize that hole after re-installing the bolt. It looks to me like you have high end bolts and would have just re- installed them. But if they have been disturbed I would buy new bolts and have the big ends re-sized. For peace of mind you you should call ARP tech line and have a conversation. Let us know what you find out, it has been many years since I dealt with this stuff.
For many years I conducted engineering environmental stress testing on military gun and missile systems. Standard procedure was to torque any fastener one time, if removed, throw it away and replace with a new one. Even in our test hardware. A fasteners torque specification is rated by the fasteners material, diameter, length and thread pitch. The torque specs are the maximum torque that can be applied to the fastener before the material yields or breaks. If you go to home depot and buy a 1/2" grade 5 bolt used for assembling a work bench you can twist them with a 3/8" drive socket, while a 1/2" grade 10 bolt can be torqued to 180-200 ft. lbs. of torque without it yielding. If you cannot verify your rod bolts material and look up the torque specification on a chart, (or specified in an assembly instruction sheet) don't use them, let alone re-use them. Even though they may appear to be in perfect condition to your naked eye, they may have been yielded and may fail. I would never reuse any fastener that has been torqued. An easy test is, if you have a good dye set, you can thread the fastener through the proper diameter and thread pitch dye with your finger tips. If you have to apply much more force to run the threads through the dye, then the threads are probably stretched and or the fastener has yielded. Just my .02 cents.
I did read that the oem rod bolts were one time use which was news to me, as so much is.
From ARP FAQ:
Are ARP bolts and studs re-usable?
Yes. As long as the fasteners have been installed and torqued correctly, and show no visible signs of damage, they can be re-used. If they show any signs of thread galling or corrosion, they should be replaced. In the case of rod bolts, if any of them have taken a permanent set and have stretched by .001” or longer, you should replace them immediately. See page 29 in the catalog for more detailed information on this critical measurement.
http://arp-bolts.com/p/FAQ.php
Last edited by jimvette999; 02-01-2017 at 11:47 AM.
02-01-2017, 10:27 AM
#22
Dr. Detroit
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So i'm struggling to understand something here.... If (as some have said) rod bolts are only good for one 'torquing', how then do you check bearing clearances? I assume you have to bolt the big end of your rods together at full torque, then use a caliper to check size, and compare to your measurements on the crank and make sure your in spec, correct? If you do this, then aren't your bolts already stretched and no good anymore? What am i missing here? If I use my old bolts when I measure for clearance, then use new, stronger, ARP 2000 bolts (for example), will my tolerances not change? This is the question I originally started this thread about because I read some horror stories about things going south quickly on guys that did nothing but change rod bolts and ended up burning bearings, cranks, etc. Again, maybe this is just being over-thought, I tend to do that, but I'm a bit of a perfectionist. OH, and here is a pic of my bolts. Anyone recognize and know the mfg??
I would buy a new set of 8740 ARP bolts and torque them to 47 ft/lbs. with moly paste. This is the backyard way to do it....but it works at this level.......when you start getting into 7000 rpm engines, you need a stretch gauge.......
If you can afford it...buy one....they are a neat tool.....but the 47 ft/lb. number is a good one and is what Eagle specs out of the box for small block rods. Skip the ARP 2000......not needed here....and when you get the new bolts....torque them to spec and measure for out of round....I really doubt they will be.......but anything can happen.
Jebby
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Jebbysan (02-01-2017)
02-01-2017, 11:47 AM
#24
Melting Slicks
Another for NEW rod bolts.
Bolts are CHEAP in comparison to the expense and labor rebuilding the motor all over again, it only makes sense. It's your motor and your wallet. 
02-01-2017, 11:49 AM
#25
Melting Slicks
02-01-2017, 07:53 PM
#26
Pro
Thread Starter
For many years I conducted engineering environmental stress testing on military gun and missile systems. Standard procedure was to torque any fastener one time, if removed, throw it away and replace with a new one. Even in our test hardware. A fasteners torque specification is rated by the fasteners material, diameter, length and thread pitch. The torque specs are the maximum torque that can be applied to the fastener before the material yields or breaks. If you go to home depot and buy a 1/2" grade 5 bolt used for assembling a work bench you can twist them with a 3/8" drive socket, while a 1/2" grade 10 bolt can be torqued to 180-200 ft. lbs. of torque without it yielding. If you cannot verify your rod bolts material and look up the torque specification on a chart, (or specified in an assembly instruction sheet) don't use them, let alone re-use them. Even though they may appear to be in perfect condition to your naked eye, they may have been yielded and may fail. I would never reuse any fastener that has been torqued. An easy test is, if you have a good dye set, you can thread the fastener through the proper diameter and thread pitch dye with your finger tips. If you have to apply much more force to run the threads through the dye, then the threads are probably stretched and or the fastener has yielded. Just my .02 cents.
Thanks OCB
02-01-2017, 08:27 PM
#28
Pro
Thread Starter
Great point, I had forgotten about that...it's an important thing to have forgotten too.
I believe that the theory behind the ARP rod bolts is that you're not approaching their load limit at the stretch recommended therefore you can reuse them. They actually recommend you torque them several times before putting into service to burnish the threads and seating surface of the bolt head & cap.
I did read that the oem rod bolts were one time use which was news to me, as so much is.
From ARP FAQ:
Are ARP bolts and studs re-usable?
Yes. As long as the fasteners have been installed and torqued correctly, and show no visible signs of damage, they can be re-used. If they show any signs of thread galling or corrosion, they should be replaced. In the case of rod bolts, if any of them have taken a permanent set and have stretched by .001” or longer, you should replace them immediately. See page 29 in the catalog for more detailed information on this critical measurement.
http://arp-bolts.com/p/FAQ.php
I believe that the theory behind the ARP rod bolts is that you're not approaching their load limit at the stretch recommended therefore you can reuse them. They actually recommend you torque them several times before putting into service to burnish the threads and seating surface of the bolt head & cap.
I did read that the oem rod bolts were one time use which was news to me, as so much is.
From ARP FAQ:
Are ARP bolts and studs re-usable?
Yes. As long as the fasteners have been installed and torqued correctly, and show no visible signs of damage, they can be re-used. If they show any signs of thread galling or corrosion, they should be replaced. In the case of rod bolts, if any of them have taken a permanent set and have stretched by .001” or longer, you should replace them immediately. See page 29 in the catalog for more detailed information on this critical measurement.
http://arp-bolts.com/p/FAQ.php
Those bolts are CAT power products probably along with the rods......
I would buy a new set of 8740 ARP bolts and torque them to 47 ft/lbs. with moly paste. This is the backyard way to do it....but it works at this level.......when you start getting into 7000 rpm engines, you need a stretch gauge.......
If you can afford it...buy one....they are a neat tool.....but the 47 ft/lb. number is a good one and is what Eagle specs out of the box for small block rods. Skip the ARP 2000......not needed here....and when you get the new bolts....torque them to spec and measure for out of round....I really doubt they will be.......but anything can happen.
Jebby
I would buy a new set of 8740 ARP bolts and torque them to 47 ft/lbs. with moly paste. This is the backyard way to do it....but it works at this level.......when you start getting into 7000 rpm engines, you need a stretch gauge.......
If you can afford it...buy one....they are a neat tool.....but the 47 ft/lb. number is a good one and is what Eagle specs out of the box for small block rods. Skip the ARP 2000......not needed here....and when you get the new bolts....torque them to spec and measure for out of round....I really doubt they will be.......but anything can happen.
Jebby
Thanks Guys
02-01-2017, 11:01 PM
#29
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Wow...this has gone on a long time. I agree those are not ARP bolts....but they are going to be much better than OEM. With experience you can "feel" when a bolt isn't taking torque. Engines are rebuilt every day with old OEM bolts and they do fine if they haven't been stretched to yield. Same with ARP bolts....they are re-used constantly. Take a look at a Top Fuel engine that is rebuilt several times in a weekend....bolts aren't changed constantly. They take care but they torque them fast. These type bolts are not a one time use by design. My 540/555 has been apart numerous times in the last 15 years. I added a new set of ARP 2000's to it somewhere along the line just for fun...but no reason to suspect the old ones were going to fail. I later changed to Oliver rods with ARP 625 bolts. They've been apart once when I converted it to a turbo configuration. They had been torqued with a stretch gauge and readings recorded. They were fine and I stuck them right back in. And even with ARP lube it took a lot more than the TQ spec to get them stretched to the right measurement.
Worst case....I'd order a new set of 8740 bolts from ARP and put them in. I wouldn't worry about re-sizing the rods. They'll be fine as long as bearings looked good when you took it apart.
JIM
Worst case....I'd order a new set of 8740 bolts from ARP and put them in. I wouldn't worry about re-sizing the rods. They'll be fine as long as bearings looked good when you took it apart.
JIM
02-02-2017, 08:26 AM
#30
Pro
Thread Starter
Wow...this has gone on a long time. I agree those are not ARP bolts....but they are going to be much better than OEM. With experience you can "feel" when a bolt isn't taking torque. Engines are rebuilt every day with old OEM bolts and they do fine if they haven't been stretched to yield. Same with ARP bolts....they are re-used constantly. Take a look at a Top Fuel engine that is rebuilt several times in a weekend....bolts aren't changed constantly. They take care but they torque them fast. These type bolts are not a one time use by design. My 540/555 has been apart numerous times in the last 15 years. I added a new set of ARP 2000's to it somewhere along the line just for fun...but no reason to suspect the old ones were going to fail. I later changed to Oliver rods with ARP 625 bolts. They've been apart once when I converted it to a turbo configuration. They had been torqued with a stretch gauge and readings recorded. They were fine and I stuck them right back in. And even with ARP lube it took a lot more than the TQ spec to get them stretched to the right measurement.
Worst case....I'd order a new set of 8740 bolts from ARP and put them in. I wouldn't worry about re-sizing the rods. They'll be fine as long as bearings looked good when you took it apart.
JIM
Worst case....I'd order a new set of 8740 bolts from ARP and put them in. I wouldn't worry about re-sizing the rods. They'll be fine as long as bearings looked good when you took it apart.
JIM
Anyway, the rod journal on that piston looked just fine which I thought was odd, but I suppose the journal is harder than the bearing. My concern is that the tolerances when originally assembled weren't right, and slapping a new set of standard size bearings in there and bolting it back together may result in the same issues. My #1 journal did have a very slight score in it. You can feel it ever so slightly if you run a fingernail over the journal side-to-side. No idea if this is OK, or if I need to get it polished out? Grinding would seem like overkill for what it is, but again, I am no expert on this.
If I need to get the crank polished, might I need to up-size the bearings, or is polishing not going to remove enough material to require that?
Thanks,
Greg
02-02-2017, 09:51 AM
#31
Dr. Detroit
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Now with stock rods and nuts....no way.
A bolt comes out and goes back in.....there is no stud to press in and out and minute differences in straightness at the stud can cause lopsided clamping forces...
On a 500-600 horse 6500 rpm engine the bolts are almost overdesigned anyway......never seen one come apart due to fatigue but they will cycle fatigue and stretch after a few torques......
I say no problem on a second usage but a third is pushing it.....
Jebby
02-02-2017, 01:30 PM
#32
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Probably shouldn't admit it...but many years ago I swapped many bolt/nut setups out by knocking them out and the new ones back in. Never checked for any out of round and never had a problem. Just gotta be careful.
Got any pics of the damaged bearing? If something got in there...it would be grooved....but is there any signs of the bearing burning up or flaking? At this point, you've raised enough questions about the previous builder it couldn't hurt to ck things. You can buy a cheap dial bore mic and an outside Mic and do well enough at home pretty easily to check everything. Polishing the crank doesn't remove measureable metal (not enough to worry about). If someone removes that much by polishing it will likely be out of round when done. If there is a scratch or divot in a journal that is not raised above the surface, I wouldn't grind it just for that. It won't hurt a thing. Think of it as a tiny oil reservoir! You can polish it at home with a shoe string and a piece of 1000 or 1500 grit sandpaper if it's like what you described.
Yes...bearings are softer than the crank. Especially stock replacement style. "Race" type bearings are harder and are less likely to allow something to embed into them. I typically don't use the harder race bearings on a cast crank. It's good that whatever got in there damaged the bearing and not the crank.
JIM
Got any pics of the damaged bearing? If something got in there...it would be grooved....but is there any signs of the bearing burning up or flaking? At this point, you've raised enough questions about the previous builder it couldn't hurt to ck things. You can buy a cheap dial bore mic and an outside Mic and do well enough at home pretty easily to check everything. Polishing the crank doesn't remove measureable metal (not enough to worry about). If someone removes that much by polishing it will likely be out of round when done. If there is a scratch or divot in a journal that is not raised above the surface, I wouldn't grind it just for that. It won't hurt a thing. Think of it as a tiny oil reservoir! You can polish it at home with a shoe string and a piece of 1000 or 1500 grit sandpaper if it's like what you described.
Yes...bearings are softer than the crank. Especially stock replacement style. "Race" type bearings are harder and are less likely to allow something to embed into them. I typically don't use the harder race bearings on a cast crank. It's good that whatever got in there damaged the bearing and not the crank.
JIM
02-02-2017, 07:02 PM
#33
Drifting
I would never reuse rod bolts!They stretch are one and done IMO.If you reuse them your motor MIGHT grenade!!! Why take a chance?
Last edited by gjohnson; 02-02-2017 at 07:03 PM.
02-02-2017, 08:39 PM
#34
Pro
Thread Starter
Probably shouldn't admit it...but many years ago I swapped many bolt/nut setups out by knocking them out and the new ones back in. Never checked for any out of round and never had a problem. Just gotta be careful.
Got any pics of the damaged bearing? If something got in there...it would be grooved....but is there any signs of the bearing burning up or flaking? At this point, you've raised enough questions about the previous builder it couldn't hurt to ck things. You can buy a cheap dial bore mic and an outside Mic and do well enough at home pretty easily to check everything. Polishing the crank doesn't remove measureable metal (not enough to worry about). If someone removes that much by polishing it will likely be out of round when done. If there is a scratch or divot in a journal that is not raised above the surface, I wouldn't grind it just for that. It won't hurt a thing. Think of it as a tiny oil reservoir! You can polish it at home with a shoe string and a piece of 1000 or 1500 grit sandpaper if it's like what you described.
Yes...bearings are softer than the crank. Especially stock replacement style. "Race" type bearings are harder and are less likely to allow something to embed into them. I typically don't use the harder race bearings on a cast crank. It's good that whatever got in there damaged the bearing and not the crank.
JIM
Got any pics of the damaged bearing? If something got in there...it would be grooved....but is there any signs of the bearing burning up or flaking? At this point, you've raised enough questions about the previous builder it couldn't hurt to ck things. You can buy a cheap dial bore mic and an outside Mic and do well enough at home pretty easily to check everything. Polishing the crank doesn't remove measureable metal (not enough to worry about). If someone removes that much by polishing it will likely be out of round when done. If there is a scratch or divot in a journal that is not raised above the surface, I wouldn't grind it just for that. It won't hurt a thing. Think of it as a tiny oil reservoir! You can polish it at home with a shoe string and a piece of 1000 or 1500 grit sandpaper if it's like what you described.
Yes...bearings are softer than the crank. Especially stock replacement style. "Race" type bearings are harder and are less likely to allow something to embed into them. I typically don't use the harder race bearings on a cast crank. It's good that whatever got in there damaged the bearing and not the crank.
JIM
Something else.... I reached out to SCAT yesterday asking for recommendations on rod to journal clearances, and the guy said "we don't make recommendations, try Youtube....." YHTBFKM was my first thought. Apparently even if I were to provide significant information about my build and intended use, they still would not make recommendations as there are "too many variables".. Seriously?? So, what should I be looking to get for clearances with a ~500 hp, 5w-20 oil, naturally aspirated, ~6500rpm max, street car....
02-02-2017, 08:57 PM
#35
Le Mans Master
I just setup my BB with .003 clearance on the rods. Eagle H-beam with ARP bolts. And that is measured clearances. Bearing diameter-crank diameter=.003 I don't have much faith in plastigage.
02-03-2017, 09:26 AM
#36
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You had some trash go through there. Could have happened during the original assembly. From those pics I don't see anything that scares me about it not having enough clearance.
The rule of thumb is .001" for each inch of journal diameter. So for a small block you've got a 2.45" main and a 2.100" rod. You're looking at around .0025 for mains and .002" for rods. A little looser is better than a little tighter especially if you're going to spin it up hard. Especially on mains. You have to account for any crank runout and if it's a little tight it will make contact especially if it flexes a little.
The old joke is if it's a little looser...you'll know it....if it's a little too tight...everyone will know it when it comes apart!
If everything is dead on perfect "NASCAR" style...you can tighten things up....but this stuff ain't that good.
JIM
The rule of thumb is .001" for each inch of journal diameter. So for a small block you've got a 2.45" main and a 2.100" rod. You're looking at around .0025 for mains and .002" for rods. A little looser is better than a little tighter especially if you're going to spin it up hard. Especially on mains. You have to account for any crank runout and if it's a little tight it will make contact especially if it flexes a little.
The old joke is if it's a little looser...you'll know it....if it's a little too tight...everyone will know it when it comes apart!
If everything is dead on perfect "NASCAR" style...you can tighten things up....but this stuff ain't that good.
JIM
02-03-2017, 09:27 AM
#37
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BTW= flip the bearing over and take a pic of the numbers/codes on the back of it.
JIM
JIM
02-03-2017, 10:18 AM
#38
when building a engine you assemble the rods in a rod vise and torque to spec and measure the inside diameter of the bearing. then you measure the diameter of the crank pin to find the clearance. you do NOT throw out those rod bolts when you assemble the engine so don't worry about using them over. only if the bolts will not pull up to spec either using a torque wrench or a bolt stretch gauge do you need to replace them
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gbarmore (02-03-2017)
02-03-2017, 10:27 AM
#39
Dr. Detroit
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You had some trash go through there. Could have happened during the original assembly. From those pics I don't see anything that scares me about it not having enough clearance.
The rule of thumb is .001" for each inch of journal diameter. So for a small block you've got a 2.45" main and a 2.100" rod. You're looking at around .0025 for mains and .002" for rods. A little looser is better than a little tighter especially if you're going to spin it up hard. Especially on mains. You have to account for any crank runout and if it's a little tight it will make contact especially if it flexes a little.
The old joke is if it's a little looser...you'll know it....if it's a little too tight...everyone will know it when it comes apart!
If everything is dead on perfect "NASCAR" style...you can tighten things up....but this stuff ain't that good.
JIM
The rule of thumb is .001" for each inch of journal diameter. So for a small block you've got a 2.45" main and a 2.100" rod. You're looking at around .0025 for mains and .002" for rods. A little looser is better than a little tighter especially if you're going to spin it up hard. Especially on mains. You have to account for any crank runout and if it's a little tight it will make contact especially if it flexes a little.
The old joke is if it's a little looser...you'll know it....if it's a little too tight...everyone will know it when it comes apart!
If everything is dead on perfect "NASCAR" style...you can tighten things up....but this stuff ain't that good.
JIM
Why 5w20 oil? I like something a little heavier.......and not for the bearings.....for the rest of the engine......
Jebby
02-03-2017, 01:35 PM
#40
Pro
Thread Starter
You had some trash go through there. Could have happened during the original assembly. From those pics I don't see anything that scares me about it not having enough clearance.
The rule of thumb is .001" for each inch of journal diameter. So for a small block you've got a 2.45" main and a 2.100" rod. You're looking at around .0025 for mains and .002" for rods. A little looser is better than a little tighter especially if you're going to spin it up hard. Especially on mains. You have to account for any crank runout and if it's a little tight it will make contact especially if it flexes a little.
The old joke is if it's a little looser...you'll know it....if it's a little too tight...everyone will know it when it comes apart!
If everything is dead on perfect "NASCAR" style...you can tighten things up....but this stuff ain't that good.
JIM
The rule of thumb is .001" for each inch of journal diameter. So for a small block you've got a 2.45" main and a 2.100" rod. You're looking at around .0025 for mains and .002" for rods. A little looser is better than a little tighter especially if you're going to spin it up hard. Especially on mains. You have to account for any crank runout and if it's a little tight it will make contact especially if it flexes a little.
The old joke is if it's a little looser...you'll know it....if it's a little too tight...everyone will know it when it comes apart!
If everything is dead on perfect "NASCAR" style...you can tighten things up....but this stuff ain't that good.
JIM
The bearings are standard King units. I was considering upgrading to the HP series, but with a 4x cost premium, I figured I'd ask for an opinion here...
