I am building a B18C5 motor from scratch with all oem brand new parts. I have been following the factory service manual to the T for all the torque specs and the methods for installing everything. Today I got to installing the cams and cam caps and ran into a problem.

I installed the cams pre-lubed with Torco assembly lube and then lubed the threads per the service manual and loosely tightened the cam cap bolts in the designated order via the service manual. Then I used my 3/8" Snap-On torque wrench which has never been out of spec when I've had it checked by Snap-On and I could not successfully torque the bolts.

I was sure to put the crank at TDC, put the cams in with the keyway facing upward to prevent having the cams being placed at a full valve open situation causing undue tension. So I'm at a loss as to why they are stretching and breaking. These parts have never been assembled other than a quick non torque when delivered to me in a head assembly from Acura.

I have read other posts like this but it seems no one had a better solution than to just "tighten by handa and leave it that way". I can't believe that is better than knowning that the valvetrain is torqued properly. It seems to me that the tensile strength of the bolt is not sufficient to hold the torque being applied.

The threads appear to be fine, the bolt is threading ok, not binding, however the threads are stretching instead of the head of the bolt tightening down onto the cam cap holders. Does anyone know of a better method of tightening these or does anyone have a solution? Maybe ARP has a replacement? Here is a picture of what I am talking about. Again these bolts have never been torqued before other than the attempt I made when tightening them down the first time. The cam caps were seated, not bound on the dowels.

In the pictures you can clearly see where the threads of the bolts are stretched. One broke on me and I was able to get the remaining out of the head. But I attempted to torque them again and another bolt in the same hole started to stretch, and others began to stretch as well so I stopped.

 

Samething happend to me the other day. When I went to loosen the bolt I heard a loud pop sound. Knew it was snapped but I got lucky it snapped only 3/4 of the way.

 

i would run a re-threader through all the threads and replace all of the cam cap bolts...theyre probably stretching like that because theyve possibly been torqued down too many times. fresh threads with fresh bolts should do the trick.

 

I totally agree with you if they had been previously been torqued down as this was my first thought, much like a head bolt that has stretched, it is reaching its yeild point prior to achieving the correct torque.

As I said before though, this head was bought as an assembly from Acura which comes pre-assembled with only the valves, valvesprings, the cams, rockers come separated and need to be assembled. The way the head arrived, the cam cap bolts were installed, but not torqued as I could remove them by hand, they were merely finger tight for transport.

I will order the cam cap bolts all new and begin again and hope for a better outcome but I really wish ARP made a replacement, I searched and was only able to find GReddy high tensile strength cam cap studs for a GT-R RB26 motor. Nothing for hondas unless its flywheel bolts or headstuds.

 

ohhh, i missed that part....in which case, i would switch to a 1/4" torque wrench that reads in/lbs. perhaps your torque wrench is having difficulty torqueing that low....could have just bypassed the click, and you keep torqueing waiting for it to click...it has happened to me.

 

Nope, I've used this torque wrench for the better part of 4 years, I've worked on various hondas for 6 years +. The torque wrench goes from 5 ft-lbs to 35 ft-lbs only. I basically bought it to do everything that the middle sized 3/8 was having a hard time doing. And then the 1/2 torque wrench is for everything larger than that. I torque the bolts very smoothly not jerking and it clicks very noticebly when going slowly, you can feel and see the head of the tool move.

I never invested in a 1/4 torque because basically anything under 20 ft-lbs could be hand tightened anyway unless it was something vital like this so my 3/8 could easily do the job very reliably.

 

i know, but ive had the same thing happen to me on cam caps, where the wrench just didnt click, and i kept stretching the bolt. but when it happened to me, i just say..."ive gone way over, so im just gonna leave it" lol. just throwing out a suggestion, i know snap on torque wrenches are among the best.

 

well thanks for the non-dick like responses, sometimes I wonder why people even waste their time on here posting the things they do almost effectively trying not to help. I think what I'm going to do is just order the new cam cap bolts and re-attempt to torque them. I'll post up my outcome whether or not they turn out ok, but I'll have to wait to receive them because of the holiday weekend. Wish me luck. Thanks again.

 

i was unaware of my hasty remarks...

 

no, not directing anything toward you, its just that I have had several of my posts go completely unanswered or locked or moved and then buried on this forum. I used to use it as a great form of information back before the change to VBulletin. Its just refreshing to have someone answer clearly and concisely for a change, that is why I said thank you.

 

What torque spec did you use? 20 ft-lb for the M8s and 7.2 ft-lb for the M6s. I have not had an issue and mine have been torqued three times. If they are stretched from the factory on a new OEM head, I would ask Acura to replace them. Are you stretching/snapping new bolts as well?

 

sorry, i misread. im so used to people being sarcastic on here....so i know what ur saying....good luck to you, and i hope you get this issue resolved!

 

Absolutely, the bolts are brand new, they have never been torqued to my knowledge before today. I used the 20 ft-lbs for the 20 M8s and 7.5 ft-lbs for the M6s because my torque wrench only goes in .5 ft-lb increments. I have also re-used these bolts on a friends LS VTEC motor that I rebuilt for him and that motor had a very questionable history. All the cam cap bolts went on fine and were torqued with the same torque wrench with no problem.

All I can possibly contribute this to is possibly the bolts are more stressed with the dual valve spring setup on the Type R head? I know its probably not the case but I'm wondering if that is contributing to it at all. It can't be the threads in the head being messed up as evidenced by the bolt threads stretching. Honestly the first time it started to stretch I thought for sure I had stripped the aluminum threads in the head. It appears to be stretching at the point where the cam cap meets the top deck of the head.

 

try tightening them all in 5-8lb increments.

10 lbs. 15lbs. 20lbs.

 

Double check the total length, I had a set of cam cap bolts brand new from honda that were too long, the first one stretched like the one pictured. I double checked the length and found they were bottoming out in the head.

 

I can see how too long of a bolt in a blind hole can cause a bolt to break but I doubt it would break the way mine are. If the bolt was too long I would expect the break to be a clear shear break across the weakest part of the bolt, most likely where the threads begin or at the head of the bolt, the likely stress risers.

This breakage is clearly shown as being a tensile issue as the bolt is being stressed beyond its ability to hold diameter. The threads are continuing downward into the head while the head of the bolt is remaining above the cam cap. The bolt is deforming and not holding the tension it should between the threads in the head and the head of the cam cap bolt to the cam cap.

 

I did tighten them in 2 steps as I do with anything that is a sequence unless like headbolts it has a specified stepped torque sequence. I tightened each down snug, not tight at all, basically until I felt some resistance leaving probably slightly less than a .0625in between the cam caps and the head in the same sequence as the final step. Then I began tightening starting from the top center bolt and working my way out with the torque wrench as shown in the service manual. I was checking each cam cap to assure that each was not binding on the dowels as is common when the cam is pushing unequally against the valvesprings. All cam caps would tighten down equally to the head and when attempting to tighten to the specified 20 ft-lbs is when I had the bolts stretch which feels exactly like the hole is stripping as the bolt is plastically deforming.

 

Just so you all don't think I'm blowing smoke up your *** about it being ALL brand new parts.






This picture was taken after rocker shafts and rockers were installed but the cam caps were again just finger tight like how I received the head from Acura, I just put the bolts back in so I wouldn't lose them.

 

So the bolts come assembled on the head. Are they tight when shipped? I'm wondering if they didn't damage them at the factory during assembly.

 

 

The new Honda cam cap bolts does not look to be heat treated. The bolts are silver in appearance and not black like the originals. Broke 2 out of the 20 I bought. It was used on stock valvetrain by the way.

 

are you sure thats not anti-corrosive? come to think of it, arent cam cap bolts usually black? good lookin out. but 20lbs? a grade 2 bolt can handle that.

the best thing i can come up with is just like companies like crower, when they make 100,000 valvespring retainers, its possible for 1500 of them to come out bad. looks like honda got into a bad batch of bolts

you could just measure that thing, and buy hardware online. something highgrade. thats the route i would go. because if you walk into acura with a handful of those they are just going to shrug their shoulders at you.

 

I'm glad we are all thinking on the same plane here. This was one of the several thoughts that has been crossing my mind as of late. Just for the hell of it I took one of the longer cam cap bolts that serves double duty as a cam cap and as a valvecover/spark plug cover stud and used it in the same hole as the bolt that broke and go figure, the bolt torqued to 20 ft-lbs no problem.

These bolts are black and when torqued show now sign of fatigue which is what I can "feel" in the torque wrench when tightening the standard hex head silver bolts which make up the rest of the cam cap bolts. I truely think that the bolts are sub-grade or not heat-treated and this is why they are not being able to be torqued. Having built several motors and done countless headgaskets I have never come across this problem especially with brand new oem parts. I think I may buy some better grade cam cap bolts and go from there. Again thanks all for the continued support and suggestions, I really want to get this motor put together this weekend if possible.

 

upon further investigation I have searched on google for images of honda camshaft installation pictures and none have shown the cam cap bolts to be silver, all are black in every picture I have found. I wonder if someone screwwed up in the assembly of this and simply used stock on hand, 8-1.25mm 50mm long non heat treated bolts instead of the proper heat treated ones. I still think I am going to order them from honda to see if when I get them separately if they are black.

 

When did you buy these? So are you saying that the original style black heat-treated bolts are no longer available? If that is the case then I am going to have to source some 3rd party bolts because these are obviously not up to the task.