<VV> Re: sleeved valve guides, and bronze

[Bill Hubbell]

Just to offer a counterpoint, replacing valve guides is not all that
difficult if you have the right tools.  Yes, the heads should be heated to
300+ degrees, which can be done in any standard oven or barbecue grill.
Then , for easy removal of the guides, spray them with liquid nitrogen and
they will almost fall out of the head with no removal of aluminum.
Installation of new guides is the reverse of above, soaking the guides in
liquid N2 before insertion.  You should also have the tool for installing
and removing the guides, available from Clark's and probably other sources
as well.  After guides are installed, the valves will need to be reground to
insure proper seating.

Bill Hubbell

----- Original Message ----- 
From: <BobHelt@aol.com>

<SMIT> Similarly, you can replace the old guides with new
> ones. But there are potential problems here too. The head has to be heated
to 300+
> or so degrees to get the guides out. Also does the shop have a fixture and
an
> appropriate press, or will the mechanic get a BF hammer and start banging
on
> the guides? I doubt that all the banging is good for the seats and the
> stuctural integrity of the head (think warp...) Then there is the cost
involved here.
> Labor, new guides, heating.......  Installing the new guides is tricky
too.
> Got to get the right depth. Got to make sure the fit is tight because
removing
> the old guides removes some material. Usually 0.001 in. oversize guides
are
> installed. Do they go in easily...or are they a bear? Now that you've got
new
> guides installed, you have to be sure that the stem hole is PERFECTLY
concentric
> with the valve seat insert. If not, grinding the valves will be a problem.
> Often you will find the stem hole is not concentric and will require some
work
> or another new guide. Anyhow there are potential problems and lots of
costs
> here.