Fastener engineers - need some confirmation

[Elombard]

I have B&B headers on my 3.2. The lower valve cover cannot be removed due to clearance, I think most folks shorten the lower valve cover studs a little so they can be removed.

I was thinking of replacing the studs with cap head bolts.

Is this a good idea? Is there any issues with the heat and cool cycle that these will see?

I dont want to go with ARP or something $$$ just decent quality available locally.

Thanks

[juanbenae]

I suspect the torque value need for the valve covers is significantly less than a simple bolt will provide w/o backing out. the torque on the VCs is low to not cause warp-age hence the fresh nylocks with every gasket kit. maybe the lightest (green? blue?) thread locker would aid in keeping the torque w/I range and lessen the backing out opportunity? usually a little heat will free up the lighter thread lock compounds.

[Elombard]

ahh Its the nylocks that are the key.

I bet you are right a regular bolt will not stay torqued at the light load.

I will consider the light thread lock.

thx

[juanbenae]

before you run out and by thread lock maybe wait until someone smarter than me chimes in.

the only other thing I would consider is possibly some of the single use schnor (SP?) washers that are so prevalent on these cars. thing is with the covers being aluminum any regular lock washer might gouge them significantly. they are often used on low torque bolts that will affix to aluminum.

[peon77]

you could replace the studs, there are cap head bolts with a nyloc insert but you would have to heli-coil each hole that gets a bolt.

[Elombard]

eeew dont want to go to that much trouble

[walt]

A drop of blue loctite. Medium strength but removable with hand tools.

[Elombard]

What class of bolt should I look for? Just something in mild steel to match the expansion characteristics of the stock studs?

[Jonny042]

Just thinking out loud, but drilled heads on allen head bolts and safety wire could work too.

[Harpo]

Because the stud is threading in to aluminum and most import because this is a serviceable joint please don't use a bolt. Yes please use nylon lock nuts. Please don't use a schorr washer on aluminum. I also like blue locktite.

I don't know the grade of the fasteners in question but here is the rule of thumb that I utilize when ever designing fastener joints in to aluminum.
Grade 8.8 require a minimum of 1.6 x diameter of threaded engagement in to aluminum
Grade 10.9 require a minimum of 2.0 x diameter of threaded engagement in to aluminum

Hope this helps

[faverymi]

I would stay with nylock nuts raher than messing the threads in the cam carriers

I wouldn't re-invent the wheel. When needed I remove the headers for access

[Elombard]

Right no not going to touch the threads, I was going to use a bolt that is the same size and thread as the existing stud but shorter so I could remove it with out removing the headers.

[HaroldMHedge]

What about trying a M8 half height nyloc nut?

Edit
I believe these nuts should be grade 8 from the factory.

[eastbay]

Not much effort to try it if the valve covers are off. Be aware that some of the stud holes run through to the rocker chambers. I would try a flange head bolt with a rubber or plastic washer to seal.

edit: Just checked some cam carriers in the shed and all the holes were blind, guess I got lucky with ones on my car as the lower row of studs are not blind. Easy to check if your VCs are off.

[Harpo]

Originally Posted by Elombard

Right no not going to touch the threads, I was going to use a bolt that is the same size and thread as the existing stud but shorter so I could remove it with out removing the headers.

I don't recommend it

David

[gtc]

Never heard of people having problems removing the valve covers. I did a few valve adjustments with B&B's on my car and don't remember any particular difficulties.

[850carnut]

You can buy some set screw style studs that have an allen head top. Then you can still use the nyloc nuts. When you need to remove valve cover just remove stud with allen wrench.

[john walker's workshop]

Just use a damn bolt w/aluminum washer and check them once in a while. Jeeze. Just need a few along the bottom. That header design sucks for clearance to the V/C studs, making an easy job a bittch.

[MConn]

Just a guess, can you add a gasket or 2 at the header-to-head flange to get the header away from the valve cover?

I'm going trough a fitment issue with M&K headers-to-bumper right now, so i feel your pain.

Mike

[Elombard]

Thanks John

I don't want to remove the headers at the moment if I don't have to.