Has any one ever took there cams out and replaced the cam and then the cam cap bolt tears through the aluminum if so this is not the worst part as i just torqed the head to 90lbs so now i cant move the head or the car...As i already helicoiled three of them already wit the head off the car....Why dont they make the head wit helicoils already inplace:3d_frown:
Cam Caps WTF....
- Thread starter 7mgte1988
- Start date
jdub;1409989 said:What did you torque to?
That's a pretty good sign the head has annealed from an over heat.
Well the proper torqe is 14lbs but i took my cam off and as i was putting back on the bolt didnot hold so i backed it off and it came out wit the threads..
Was it at the back of the head? Sounds like an annealed head. Hate to tell you this, but if it is, that head is junk.
You also have to tighten GRADUALLY in a specific pattern with the cams in a specific alignment...
Start here: http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=52
Start here: http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=52
If the head has been annealed, it's soft. The exhaust studs are not going to hold either. You can do what you like, but no way I would use that head...it should have been hardness tested before it was worked/installed.
Annealing is the process of atoms pretty much getting looser bonds between eachother due to heat. It makes the metal softer, more pliable, ductile. Unfortunately happens to alluminum at temperatures that you'd expect to get in an engine overheat.
Just something to throw out there...
Has anyone heard of cryogenning metal parts? It's supposed to be the process of cooling metal to almost absolute zero to aline the atoms in as strong a bond as possible. Would that counteract the process of annealing? Would be nice to find a use for these heads other than just throwing them out
Just something to throw out there...
Has anyone heard of cryogenning metal parts? It's supposed to be the process of cooling metal to almost absolute zero to aline the atoms in as strong a bond as possible. Would that counteract the process of annealing? Would be nice to find a use for these heads other than just throwing them out
radiod;1410389 said:Annealing is the process of atoms pretty much getting looser bonds between eachother due to heat. It makes the metal softer, more pliable, ductile. Unfortunately happens to alluminum at temperatures that you'd expect to get in an engine overheat.
Just something to throw out there...
Has anyone heard of cryogenning metal parts? It's supposed to be the process of cooling metal to almost absolute zero to aline the atoms in as strong a bond as possible. Would that counteract the process of annealing? Would be nice to find a use for these heads other than just throwing them out
there is a thread in the technical section about this...it sort of ended up going to hell though.
Also, annealing has little to do with atomic bonds. It is the elevated temperature re-organization of a the grain structure to a lower energy state. In simplified terms, this reduces internal stresses in the material - the presence of these internal stresses were what gave the material its strength, so reducing the stresses leads to a reduction in strength.
In my experience, I have yet to see cryo treated aluminum have better properties than non-cryo material. Until somebody proves to me otherwise, its all smoke and mirrors. Same cannot be said about steel/iron though.
adampecush;1410539 said:
Werd!
Aluminum and steel/iron are VERY different metals, infact, being a metal is about all they have in common!
Cyro treated cast iron is supposed to be badass stuff for certain applications... I've never heard of doing it to aluminum though?
Aluminum 'ages' naturally, and being heated speeds up the process. Aluminum left out in the sun for decades can be extremely brittle, for instance. Anyway, once a sample has been annealed to a 'full soft' state, there's no way to get it back to a hardened state while retaining dimensional stability.
Materials sciences was a looooooong time ago though...
adampecush;1410539 said:
Anecdotal evidence I know but it does machine "differently" before and after Cryo Adam, seems to be less "sticky" on cutters so you can bump up the DoC and RoC on both. (also found a casting stays cold for a very long time after being treated)
i am curious. what did you use to torque the bolts with ? 1/4 drive or 3/8
i ask.. b/c 14 ft lbs isnt very much at all and using a 3/8 ratchet, going by feel is going to have bad results...
did you use a 1/4" torque wrench?
i ask.. b/c 14 ft lbs isnt very much at all and using a 3/8 ratchet, going by feel is going to have bad results...
did you use a 1/4" torque wrench?
7mgte1988;1411014 said:
What?
1/4 is smaller than 3/8. Most automotive torque wrenches I've seen are either 3/8 or 1/2, but there are definitely some 1/4 ones as well, for lower torque specs.
Jeff
IJ.;1410657 said:
Now you've got me interested. I might have to have some Al scrap I've got laying around cryo treated and have a look at the mechanicals/microstructure.
Interesting that it appears to alter the heat capacity and/or thermal conductivity of the Al.