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very tight, with as little as .0007" stem to guide clearance. This is because of the natural resiliency of
the bronzewall material and the ability to retain oil in the groove area between the bronzewall wire
bearing surfaces.
Bronzewall Valve Guide Cautions:
Some cylinder heads require special treatment when installing bronzewall guide bushings. For
instance, the Ford Escort head and others of this type, have very thin machined area on the top of
the valve guide for the installation of positive type stem seals. If normal bronzewall installation
procedures are followed, the top of the guide will split during the swaging process. For heads like the
Escort, it is found best to do all of the installation and tapping form the combustion chamber side of
the head rather than the top of the head. Procedure is as follows:
1. Mount the cylinder head on appropriate head stands and tap the guides from the combustion
chamber side.
2. Install the bushings from the combustion chamber side. Hold your finger at the top of the valve
guide and when the installation tool is just being felt touching your finger, stop installing the
bushing. Reverse the installation tool to break off the tang and then trim off the excess bushing. It
will be noted that approximately 2 unfinished threads will be left at the top of the guide where no
bronzewall bushing is present if this procedure is followed. This will prevent any pressure from
being applied to the thin seal of the guide during the swaging operation.
3. Swage as with normal bronzewall installation and a finished guide will result that will be reliable,
and without any cracks or chips in the seal area of the guide.
Note: There are some types of valve guides that are not rebuildable using the bronzewall process.
These are valve guides that have deep snap ring grooves machined on the OD (early Chevrolet Luv
valve guides). It will be found that the tapping operation outs the valve guide very thin at the bottom
of the snap ring groove and during the bronzewall installation process the tops of the guides will
break off. If they don't break off they will most likely come off later during seal installation or even
while the engine is running later on allowing the seal and the top of the guide to go up and down
with the valve. These valve guides, of course, are not rebuildable by knurling, installation of guide
liners, or any other rebuild process. It is best to replace these guides rather than attempt to rebuild
them.
Alternative Uses for Bronzewall:
Because of the very nature of the bronzewall process, it is an appropriate repair for reducing the
diameters of small holes such as throttle-shaft bores in carburetors, kinkage bushing pivot points,
small motor bearings and any other small bearing bore diameter that can be tapped and have an
insert put in it. The bronzewall bushing can be trimmed to any length ahead of time before
installation which makes it very handy for small repairs. In most cases, the excellent wear
characteristics of bronzewall wire will equal or be better than original bushings.
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