Installing valve guided Knucklehead

[DANPATCH]

Should i heat the head before pressing in the new guides . Or press them in cold . Thanks for all the help.

[Robert Luland]

I will definitely make your job easier, While your at it throw the guides in the freezer. Bob L

[T. Cotten]

With all due respect Folks,

The interference fit between guide OD and head bore should be carefully measured no matter what.

Upon installation, if a heated head and chilled guide just fall together, how do you have any feel for how tight the resulting fit might actually be?

...Cotten

[DANPATCH]

I was wondering the same thing.What is the best way to see if you need over sized guides. On other projects I would just judge how tight they were when I installed them cold.

[billpedalino]

I heat the head and cool the guide to remove them - in all harley heads. I have always installed them cold in order to 'feel' the fit.

[Robert Luland]

What I don’t understand is if ya got the old one out and you mike the hole. You know the interference fit you want? Then why can’t it be done either way? I just don’t understand the reason to beat up the head if you don’t have to but I’m sure there are reasons that it’s done the way it is. I'm not trying to be a wise ass here, just trying to learn. Bob L

[junkyarddog]

No one is saying anything about cleaning the guide before removing.
Especialy the exhaust guides.
Just bead blasting is no good enough.
The Exhaust gets distorted and larger and has a very hard and abraisive crust build up.
After I blast I use a die grinder with a carbide burr to grind the O.D. undersize, all the way until I have cleaned off a very little of the material of the head casting.
If you get to shiny metal that should be enough.
I messed up the 1st Pan Head I removed a guide from. Had to bore the guide hole and make a .025 guide.
Never again.
Jim