Our Services

Yamaha & Mercury Cylinder head repair, automotive and light truck.

Baltimore Head Works is a state of the art machine shop specializing in the repair and remanufacture of cylinder heads for both automotive and marine.

Services include:

Yamaha & Mercury four stroke Outboard Cylinder head repair

Seat and guide machining-
is the most demanding process of the cylinder head rebuilding process. This is particularly true
with the newer engine designs that utilize multiple small valves with small dimensions, short valve guides and hard valve seats. These parts demand close tolerances and are challenging to work with. Concentricity, which is the relationship between the center line of the valve guide and
the valve seat, is also difficult to maintain with these parts. Older design machines just cannot maintain these tolerances. As a result of these demands, Baltimore Head Works utilizes the Newen, GII seat and guide machine with the live pilot system and CNC accuracy. The GII has now set the standard in the industry


consumes about half of the time required to rebuild a cylinder head . Cleaning is done in several different ways and may be repeated several times between machining operations.
> Pressure washing is the first step. Get the dirt and oil off so the head can be checked out.
> Bead blasting of valves and ports.
> Aluminum oxide blasting for cast iron .
> Ultrasonic cleaning for concealed carbon deposits and before final assembly.

Pressure testing-
is done on all heads prior to any machine work to assure a sound and crack free casting.
Pressure testing is accomplished with a “Delta” pressure tester.

Milling, surface-
is accomplished with a “DCM” mill utilizing “CBN” cutters. This machine imparts a surface finish below an Ra of 20. That’s smooth! With the introduction of “MLS” gaskets, multi layered steel, smooth is not only better it is necessary. All valve jobs get milled to not only flatten the surface but also to give the head gasket a better environment in which to seal.

Line boring-
is performed on any over head cam cylinder head that has been over heated, warped and the cam binds in the cam journals. The cam caps are simply machined at their mating surface, reattached to the head forming a smaller opening for the camshaft and the head is then machined back to it’s original dimensions. Many over headed or oil starved heads have been saved with this procedure.

is performed on heads that have been warped, usually bowed up in the middle, from over heating.
A cylinder head that would otherwise have to be scrapped can many times be straightened. This is done with the use of an oven, a torch or both. A head that cooperates most often then does not have to be line bored.

Crack repair-
is accomplished in several different ways. Is the crack repairable by welding or by using lacing plugs.

Welding requires that the crack be completely cut out first. The head is then heated in an oven to approximately 450 degrees then the TIG welding process starts. The head is allowed to cool slowly, preferably over night. The head is then pressure tested again.

Lacing plugs are also used . Plugs from manufacturers such as Loc N Stitch, and Time Sert are used as an economical way to repair a small crack thus avoiding the additional expense of welding. Cracks between valve seats are the most common repair of this type.

Thread repair-
for spark plug threads and fasteners. Inserts from manufacturers such as Heli Coil, Time Sert and Loc N Stitch are used depending on the particular application. The 5.4L Ford, short thread spark plug engine, is repaired using inserts developed by Loc N Stitch. All inserts are installed using Loc Tite thread sealant.

Baltimore Head Works is a small company that is equipped with the most modern machinery available today. Combined with years of experience the company can produce a quality product in a timely manner.

Although Baltimore Head Works will tackle almost any cylinder head, automotive and light truck, they are best know for their expertise with the following-

4 cycle outboard motors, Honda, Mercury, Yamaha, Suzuki
Cadillac Catera 3.0L
GM Northstar
Volkswagen VR6
Line Boring
Crack Repair