Buddy of mine gave me a set of ARP main bolts for a SBC, as I checked the package part number, Google also found me where ARP says to use 90-95 ft/lbs on them. Hmnn, more Google says that will probably distort things and I’ll need an align hone. Really don’t feel like going through that now, so question is if I torque to 65-70, will the bolts have proper clamp? I’m kinda thinking they may be “harder” than factory main bolts, so wondering if they need that much torque to work properly? I tried calling ARP, but the tech line never picked up the phone. Ive no issues reusing the original bolts, but since I have new ones I thought I’d look into it.
Main bolts/ studs, rod bolts, head bolts, whatever- align hone, rod sizing, honing with a plate, all should be done with the fasteners that will be used. No, the ARPs won't clamp correctly with stock specs. If you don't want to do the full Monty, just use the stock bolts with stock torque and save the ARPs for the next one
ARP usually gives you 3 different torque values; dry, oiled and with ARP moly. The packaging should show these values, or get the info from ARP before torquing them.
The clamping force is proportional to the bolt torque, mostly. The higher strength bolts can handle more torque. But they can also work at the torque of the original bolts, can't they? They just won't be providing any advantage over stock....so you might as well use the stock bolts....
Consider the SAE specs. Elasticity was the original circle around torque specs. Bolt stretch. I remember a neophite pulling the cast iron threads out of the block on an otherwise nice 454 LS6. (ARP bols, to their oiled specs...) Harder ain't always better... And, if that were irrelevant, we'd have powered our rubber band powered airplanes with tempered wire, no?
Kinda why I was asking (stretch I guess) and why I tried to get ahold of ARP. But then my mind was cluttered with TTY bolts used and these aren’t TTY not originals. A simple thing i complicated.
The high-strength ARP bolts will not work correctly at stock torque specs, as the bolts will not be stretched correctly at that torque, as Mike said. It's also why all machine work should be done with the fasteners that will be finished product, as the materials move around a bit, dependent on the torque applied. A good example is head bolts/studs- if you hone a block, and then bolt on a torque plate, the cylinder will then not be round, and if you touch-hone it, you will be able to tell where the fasteners are around the cylinder by looking/ measuring. Gets really strange when you get to torque-to-yield stuff, pull to torque plus a quarter turn etc. A lot of folks blow head gaskets on V-twin bikes by hammering them before they are warmed up- you have aluminum heads and cylinders, with steel studs that don't "grow" at the same rate, so the head gaskets are not adequately clamped until it is warmed up. A good rule of thumb for them is when you can't put your hand down on the rocker boxes and hold it, it's warm enough
Look up your part number on ARP's site and click on the instructions, the torque spec is there. Most of them quote 70 ft/lbs. 90-95 sounds too high to me. Here's an example... https://tech.arp-bolts.com/instructions/134-5202.pdf I've built a couple SBCs lately using a fully machined short block from GM and ARP fasteners. I always check the main clearances using a dial bore gauge with the fasteners and bearings installed just in case. Haven't had an issue yet, knock on wood.
Any aftermarket parts should of course be used according to the providers' specs- and ARP is very good with tech assistance, lots of up-to-date info on their site. This is a link to one area, Installation, which can be very helpful, explains why things work the way they do. Kinda worthless to those who already know everything though lol... There is a FAQ area in there too. One thing that is covered, that I found out a few weeks ago installing the aluminum heads on a stroker 428CJ with ARP head bolts, and was touched on in another post- they have changed their lube, and torque specs with it- the newest specs no longer have different regular oil vs ARP lube specs, now there's just one spec for the new ARP Ultra-Torque lube. In this instance, the old spec was 130 lbs-ft with the old ARP juice, but is now 100 lbs-ft with the Ultra-Torque using the same bolts. It also stresses the importance of torquing and loosening the fasteners a few cycles until they settle down https://arp-bolts.com/p/technical.php
That is probably the revised spec for the new Ultra-Torque lube, with the 90-95 being the spec for the old lube- like I just found for the FE Ford bolts- quite a difference, with only a change in lube
I guess that's why you haven't read it, and can't explain the reasoning behind what you said earlier?
Yeah, I'd be VERY afraid that 90 to 95 lb.ft. of torque would pull the threads out of the cast iron block. Probably even less than they..! Mike
Ah, get over it- you were wrong-deal with it. I know you can't possibly imagine that you might be wrong- but there you are. You could try stamping your feet- won't make you right, but I hear it'll make you feel better. There's one on every forum lol... Later for you
No, I'm not wrong. I'd just like you to answer my question. But you won't, because you figured out you're wrong.
Was squirrel wrong,,,,,? I didn’t read it that way at all . I have a lot of respect for Jim,,,,,he talks the talk,,,and walks the walk. He is an engineer,,,,,and a racer,,,,,,there is nothing like hands on experience. That’s why I keep my money with E F Hutton,,,,,and E F Hutton says,,,,,,. LoL. Tommy
"But they can also work at the torque of the original bolts, can't they?" No, that statement is incorrect, as has already been explained. The higher strength fastener will not be properly stretched at the lower torque spec for the stock bolts, and the stretching is what provides most of the the clamping force- so the additional strength of the ARP fasteners is not properly utilized, due to incorrect installation. Advocating putting something together contrary to the manufacturers' instructions and specs is bad practice, and then defending that procedure just so you don't have to admit you were wrong is lame. Inadequate clamping will allow the parent parts to slightly move and eventually stress to failure. This is what happened in '62 with the 406 Fords in NASCAR, as the power level went up, the main caps started to move slightly. The fix was the cross-bolt setup, which was included in the later race 406s and then in the 427. Same with other engines being upgraded with 4-bolt mains. OK, I'm bored now- bye
AGAIN...cast iron isn't strong enough for repeated torqings at 95 lb.ft. Probably not even one..! It's only a 7/16" coarse thread. Mike
So.... the elasticity MUST be different then, huh? ARP is claiming a 26% reduction in friction with their lubricant (70lb/ft vs 95) ?!?! Wow... that should make great gear lube!!! I find that number hard to believe.
Which of course is why it is usually a better deal to use studs when possible. One thing to consider is that the bolts are nearly fully engaged in their threads before torque loads are applied, which spreads the load over the length of the threads- still, I would try to use studs in that application. The stroked 428CJ I was just working on is going in a shock tower car, so I used bolts instead of studs, and the 1/2" setup has proven pretty stout over a few decades- I have never lost a head gasket on an FE, and have been working with 427s since 1977. ARP is the 800 lb gorilla of fasteners, their stuff works very well, and their procedures are pretty easy and work very well- follow the directions with attention to detail, and it will work. Serious racers will go to any length, even to using torque plates with a valve job (on some engines). My 505ci 427 (Genesis block) was machined at Sunnen's training center with all the tricks (circa 2004), hot coolant in the block, heated oil for honing, engine mounts attached, all that stuff. Here is a little "next level" info from 2001- "Using an ultra-sonic tester, you can accurately measure the bolt/stud stretch, which really applies the clamp load to the gasket. Not the torque. How does it work? The ultrasonic tester will send an echo into the bolt/stud and it will bounce back only if you first parallel grind the ends of the bolt/stud. Once you have all the fasteners ground install the fasteners by hand, leaving them loose so you can take a FREE length reading on every bolt/stud and mark it down. (Trace your head gasket onto a piece of paper this makes and easy place to mark down your numbers) You must know the stretch required for the fastener you are using. How many thousands equal 75%, 85% to 95% of the fasteners yield point? BTW, (TTY bolts/studs are right at 95% yield) and some are reusable. During the tightening process, I recommend using a Snap-On style dial indicator torque wrench or other that have a tattle-tail. This way you can learn and see for yourself after you have stretched the fasteners to the correct length using ultrasonics that the torque values are all over the place! Dont panic because, It doesn't matter the load from the fastener is correct."
I do know that ARP recommends tightening and loosening their rod bolts at least 3 time prior to final torque. Their website explains that you are sort of "lapping" the nut to the bolt. I used ARP rod bolts on my 312 as the original ones would not pull to the proper torque. I used the Ford torque specs (45-50 ft lb) for final assembly. That was around 15 years ago.
You know, I’ve had these a few years as I’m thinking about it, and that “90-95” was always stuck in my mind, it’s very possible , as been mentioned, ARP revised specs, but it’s also very possible I recalled those specs incorrectly or mixed them up with specs for something else. But ARP’s website clearly states 70 ft/lbs. that is well with the GM spec of 60-65. I’ll probably cinch the mains down today and measure things up at 65 then again at 70 and see what happens. I’ll check 90degrees on the caps, then 1/2 way between the saddles and 90 degrees on both sides and see what things look like. I appreciate all the input, now had ARP’s tech line answered the phone it would had made things easier
Just remember that the stock GM spec is for stock GM bolts- which should be ignored with the stronger ARP bolts. Higher torque can distort the mains a touch, if it was machined with stock bolts, one should use the stock bolts. It is yours, you can do as you wish, but you're taking a chance
Seems like some of you guys are confusing yield/tensile strength with modulus of elasticity. A steel main bearing cap fastener torqued to the specs called out by the engine manufacturer will result in the same clamping force regardless of the bolt tensile strength....they will stretch the same amount......all other things, like lubrication, bolt diameter, etc., being equal. Take a gander at the respective stress/strain curves for each material. The ARP fasteners with higher tensile/yield strength will allow a higher clamping force with a corresponding higher torque value, while the OEM bolt may reach its yield point at that higher torque value. Also, as noted above, the strength of the casting bolt hole threads needs to be considered with higher clamping forces. Depending on the way the threads were made. OEM blocks most likely vary considerably in thread quality.
Before assembly, I always clean the threads the best I can, both bolt and block. I get the bolt so clean so you can run the bolt into the block just by running your hand across the bolt head. I run it all the way in on a bare block, without the bearing, cap or crank.. This way I am well past the point of the threads that will actually do the work..
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