Slipping head bolts... better solution?
 

Guys,

This has happened on both engines though the first one came into spec and I got it done. I ended up breaking one bolt and replaced the set.

I’m torquing bolts down in five pound increments after 50 pounds... at this point hoping the washers would stop spinning but a couple just won’t cooperative.

Using ARP’s lube, I’ve brushed some under the bolt head at the shoulder and on the threads. Per ARP’s suggestion, I have sanded the bottoms of the washers and a flat plane with 80-grit in a straight pattern to rough up the surface to catch the spot face on the head. I still have a few that slip... I don’t want to break bolts, or worse, pull threads. Almost wishing I had bought studs but the heads came with the ARP bolt sets.

Post-corona this is becoming a real b itch. I am wore out.

Would appreciate some suggestions.

Are sure the bolts aren’t bottoming out ? 502 blocks have blind head bolt holes.

And 5lb increments sounds odd. Sometimes it can take that or more extra to get the bolt to move over what the actual torque is.

The increments were to avoid slippage. But I get what you mean.

The ARP head bolts I have are the ones for the 502 block. With exception of the long outside bolts, they’re the same length as the factory bolts. The long bolts aren’t slipping.

When you say slipping, what do you mean? Can you not reach a final torque or just concerned the washers are spinning while the bolt spins?

I have everything at 65 pound now. I’ll leave it over night and then back everything out and start again tomorrow evening. I did the same with the first engine and it was okay.

I made sure everything was clean on the heads (no lube between washer and head). This has been a new problem for me.

The washer no longer bites the head, the torque needed to turn the bolt decreases, and if you keep going, the bolt will stretch beyond yield.

Never heard of the 5lb increment deal. Seams as though that may have something to do with your issues. Do like 3 steps till final torque and call it good. Works for everyone else.

What is ARP calling for on their specs? Not sure, but since you have torgued the bolts once already to 65lbs and say you are gonna pull them and start over, you may wanna check stretch and see if they already have before re-torquing them.

Washer doesn't bite the head, can you spin the washer with your fingers after torquing them?

The washer is supposed to bite the head. It’s not. That’s the issue. You cannot spin the washer.

5 pounds is - don't be offended, crazy

As pointed out 3 steps is just fine

What you are really looking for in a torque spec is the clamp load that is a result of the thread pitch and the torque applied. With enough load the bolt stretches a bit to maintain tension until you stretch it so much it is permanently elongated..

Lubricant and the type of lube on the threads will change everything.

I don't remember ever being concerned about the washer spinning but a little googling brought me to an article that explains it. I learn something new every day :)

Regardless when torqueing it is important that you reach your number while the fastener is turning. The amount of torque to get it moving is way more than the moving torque. Actually we used to loosen the bolt/fastener 1/2 a turn and then in one smooth movement go to the required number.

Not your answer as I see it’s been covered well however I always run a tap through every bolt hole in the block prior to cleaning-assembly.

My machinist did a great job cleaning everything up, but I also subscribe to the idea of “trust but verify.” I ran taps through every bolt hole as soon as I had the block on the stand.

What I probably have here is some contamination of the surface where the washer meets the head. I’ll need to pull the offenders and look. That’s the only thing I can come up with.

Question... how much lubricant are you guys using when installing head bolts? I’ve tried to keep it from being excessive. I use a brush to get a nice film but without having it oozing everywhere during assembly.

Is 65# not enough?

ARP’s instruction for the bolt set is 70 pounds.

AFR says to follow the bolt manufacturer’s specifications.

Did you get the ARP washers with the bolts? There is a bevel on one side of the washer. That goes to face the bolt head.

For the rest of us, us an article on the head bolt washer turning issue:
https://www.enginelabs.com/engine-te...ng-head-bolts/

So, after reading that article, my question to ARP, since you are ‘the best’ and charge accordingly, why don’t you machine the washers this way now ?

Yep, I’m using washers from ARP that came with the bolts and they’re installed correctly. I’ve used them plenty of times before now. This is the first time they’ve been a problem.

5 lb increment is wrong and is your problem.never go less than 15 lb increments on head bolts.

That was a great article. I learned something important here.

Thanks Mike. I didn’t explain it right yesterday. I was only using that as a test when it started to slip. It wouldn’t even make that without slipping on a couple of them.

My usual method...

40# start point, 50#, 60#, 70#.


To note... they’re not all slipping. Two on one side, three on the other.

TomZ, you used 80 grit. That article said to use 60 per ARP's recommendation.
I know splitting hairs. For the sake of clarity as to what they do actually recommend.

Did you see another recommendation from ARP to use 80?

This problem seems like it has to be a problem with the threads in the block.

80-grit was the coarsest I had here at home; it’s pretty rough though and thought it would be fine for the job. I guess I can get 60 and try it. I might just call ARP to figure out what the deal is.

I had the same problem you are having. Does it feel like the torque wrench is jerking? It was a problem with the threads in the block. I could not leave it alone till i pulled some of the threads out of the block. I should of gone to studs. I think the jerking is causing the washer movement.

torque wrench's,I just use the 1/2" milwaukee impact gun,1 and done.:D joking
I do the 3 step torque,,never a problem,I also use multilayer gaskets.

I'm applying torque very smoothly and there is no jerking. I'm not bottoming out and have compared the OEM bolts to the ARPs... the ARPs (with the washer) are an 1/8th inch shorter. I have plenty of thread engagement.

I roll through the procedure and achieve, let's say, 50#'s. When I go to 60#'s, I apply the torque, it gets tighter, but then "gently" gives way about a quarter turn. I stop at that point. On the other engine (short bolt), this led to a broken bolt so I'm being extremely cautious. I don't want to hurt the block.

I'll get some 60-grit and try that I guess.

make sure you thread seal the through holes

I have felt a similar thing on an old Ford, it stretched the bolts. I was re-using old bolts.

Holes are blind on this block. Just using ARP’s lube on the threads. :)

I’ve got another brand new set I can try. I thought that maybe there was an issue reusing the bolts (though never had an issue reusing ARP head bolts). I had slippage on the other engine and when the bolt broke, I bought two new sets.

Are studs not available ?

They are but I didn't really think they were needed at this level. These engines are going to be rather mild compared to a lot of the others built around here.

I think the use of studs may be more about not stripping out your block, and the ease of teardown/reassembly, not so much the power level. I could be wrong.

abones, I get were you're coming from, and I mentioned that maybe I should have gone that route to begin with. However, there have been an uncountable number of engines built using AFR heads and ARP bolts on a Gen-VI block. The block really has nothing to do with the issue; it's the slick surface relationship of the head and washer.

I agree with SB's earlier consensus... ARP is supposed to be the best and comes with a price to match. Why haven't they come up with a solution, say similar to Chrysler (Chrysler incorporates a toothed design into their head bolt washers)? Chrysler's solution was mentioned in the Engine Labs link. I've been swamped today, but I plan on calling ARP in the next thirty minutes.

From reading the engine labs article I did learn something new. I have built and seen many engine built with no regard to washers spinning. Torque in three steps to desired final torque and run them. Works for just about everyone I know. If the friction is reduced and you happen to over torque, it is not a large enough a problem as that its ever been a problem. I almost think you are getting a little too OCD on this. Torque in three steps to whatever ARP says. lube the bolt and the washer. It works for everyone.

I would agree about the OCD, however, I cannot get to the rated torque spec (70#).

If the washer slips, the bolt keeps going because it acts like a bearing. The threads are deep in the block and eventually it exceeds the stretch of the bolt and breaks (or pulls the threads). I already broke one in another set on the other engine... a short bolt that was number five in the sequence. The new set had a couple of instances of slip but stopped and played right. This time one bolt took a full turn and was not getting to the next step but was getting tight (if that makes sense). Any more turning and the bolt would break, or pull threads (worst case).

what kinda torque wrench you using? Clicker, digital, beam scale?

You say you had them torqued to 65 and you only want 70. Are you hoping the bolt stops spinning at 70? You can easily apply more than 70 to them. The point is you need to stop at 70. If your digital vibrates. Stop. When the clicker clicks once. Stop. When you see 70 on your scale stop. The bolt will not stop. It will stretch till it pulls threads or breaks. Three steps, with lube, stop at your desired final torgue. Run that ***** hard.