Reusing a "working" head

[thedsmguy]

So, a friend of mine wants to reuse a head I have on a motor that has a bottom end knock. If we back off the head studs in the right order can we just swap it on without machine work etc? The head was not overheated etc, And I have not seen any bearing material in the oil. Can we use a Cometic HG or should we stick to a Felpro composite or? I'm literally in the middle of this project so any advice would be appreciated.

 

[MuffinMan7580]

Check it with a straight edge and feeler gauges. If you can't slide .008" under it, it's within spec (use composite). If it's perfectly flat, then you can run an MLS.

 

[Whoodoo]

I put a working head on my galant when the timing belt skipped and its been going well ever since. If you want to be on the safe side go with the composite gasket because it will be more lenient when it comes to surface irregularities

 

[IncorpoRatedX]

Quoting MuffinMan7580:
Check it with a straight edge and feeler gauges. If you can't slide .008" under it, it's within spec (use composite). If it's perfectly flat, then you can run an MLS.




exactly that.

But, to be on the safe side; pull the cam caps off, yank out all the lifters, soak them in cleaner and decompress them. Check the cam journals while the cams are out to make sure none of the damaged bearing made it up into the head.

 

There is no reason not to use it if the following things are true:
1)The surface is flat. .008 is grossly excessive. the spec is .0015".
2)Rotate the cams to extend the valves. Check my post in this thread for specs. I would buy a dial indicator and a dial caliper from harbor freight and check your valve guides and valve margins as described in that post.
3)Check the backside of the intake valves for oil deposits which would indicated bad valve seals. Now is the time to change them.

 

[Barnes]

Quoting MuffinMan7580:
Check it with a straight edge and feeler gauges. If you can't slide .008" under it, it's within spec (use composite). If it's perfectly flat, then you can run an MLS.



How straight is your straight edge?

 

.0002 across a 24" length.
Precision or "machinist's" straight edge

In other words, pretty damn straight.

Also, do not try to push your feeler gauge under the straightedge. Instead, set the straightedge down on top of the feeler. Precision straightedges are heavy, and a feeler that is thicker that the clearance will drag it. The largest size of feeler you can move freely back and forth under the gauge is the clearance. Measure straight across the head and then diagonal both directions. Check each direction in three places. (left right center). The highest clearance is your warpage.