51 Factory -
The 51 Factory is dedicated to
overhauling and restoration of Rolls Royce and Packard, V-12 Merlin aircraft
engines. We have a tremendous inventory of new original parts, in
addition to literally hundreds of tons of low time parts,
sub-assemblies, and complete engine cores. In the past 14 years, we have
acquired numerous inventories filling over twenty 48’ semi-tractor
trailers, totaling well over 600,000 lbs of Merlin engine cores and
We have every
component necessary to restore an engine in any condition.
The bulk of our
inventory is traced back to Bristol Aero Engines Ltd, Montreal, the last
commercial Merlin overhaul facility, operating in the 1950’s up to the
early 1960’s. Bristol Aero was supported directly by Rolls Royce,
receiving shipments of new overhaul components/parts, tooling/fixtures,
and extensive documentation on processes and approved repair procedures,
stamped by Rolls Royce engineers.
The entire inventory
of parts, tooling, and documentation was acquired by Cavalier Aircraft
Co. in the early/mid 1960’s.
From Cavalier, the
remaining inventory transferred to Paul Szendroi in the 1970’s. He was
employed at Cavalier rebuilding Merlin engines for their P51 conversions
and other customers. Paul set up his own shop called ‘Universal
Airmotive’ in the Chicago area, and continued on with rebuild/overhaul
of these engines for over 30 years. He is a very accomplished machinist,
and had purchased and prepared a number of machines specifically for
rebuild of Merlin engines. Some of the machines he set up/modified
line bore machine for re-boring the main case bearing journals
grinding machine to restore crankshaft journals to new condition
shaft grinding machine with precision cut masters to exactly
duplicate the original inverse radius cam lobe used on the Merlin
machine and fixture to re-grind pads on the rocker arms to as new
condition for perfect mating surface to new ground cam lobes
lapping machine and fixture
flange grinding machine
balancing machine for the supercharger rotating assy, water pump
impeller assy and supercharger planetary gear assys
valve and valve
seat grinding equipment and fixtures
In 2003/2004, the
entire inventory of parts, engine cores, complete machine shop, Rolls
Royce tooling/fixtures and all the documentation was acquired by the ‘51
Factory’ and moved to our facility in San Martin, California.
mechanic/machinist at Universal Airmotive also moved to California to
continue on with a career of restoring Merlin aircraft engines.
The 51 Factory has
further supplemented the operation established by Universal Airmotive,
with CNC milling machines, lathes, and other specialty machinery and
equipment, taking advantage of modern machining capabilities, ensuring
first class engine restorations.
processes are performed and controlled ‘in-house’ including cylinder
head crack/damage welding, machining and installation of new valve seats
and guides, and all other machining and grinding operations necessary to
properly restore a Merlin aircraft engine with fits and clearances to
‘factory new’ specifications.
contains hundreds of new in the box main bearings and fork rod/blade rod
bearings, including over/under sizes to accommodate oversize bore on the
crank case journals and undersize crankshaft journals ground below
We include a full
set of NEW (not used, re-plated) main bearings and connecting rod
bearings on every engine we overhaul.
Our investment in
the extensive inventory of parts, machines and tooling is substantial -
with the result that we will be able to re-build an engine in virtually
Most importantly, if
your engine has parts that are out of spec/below minimums, or marginal
in any way, we will have either a new in the box part, low time
original, or in some cases, a new reproduction item to replace it.
Our chief mechanic
has been overhauling Merlin engines since 1994. He has built many
Merlins of various types at Universal Airmotive, and is continuing high
quality engine restorations now at our company in San Martin.
our 'one of a kind' inventory, extensive machine shop, specialty tools,
tooling and many years of experience, we are providing the highest
quality restored engine possible for your prized Merlin powered warbird.
If you are in need
of a Merlin engine overhaul/restoration, we encourage a visit to our
facility, where we can explain and demonstrate various processes, and
provide examples of ‘before’ and ‘after’ overhaul for each significant
part/sub-assembly of the engine.
The real quality of
an engine overhaul/restoration is internal, and we welcome visits from
our customers at each phase of the rebuild process to personally
experience the workmanship in each component of your engine.
13545 Sycamore Ave
San Martin, Ca 95046
tel 408-779-4163, 408-683-2531