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Our library of information and data on the Merlin engine is second to none. In addition to the standard military overhaul manuals, we have the complete set of books and documents utilized by Bristol Aero Engines for overhaul of the Merlin engines all through the 50s up to the early 60s. This documentation was developed and updated continuously by Bristol and Rolls Royce engineers, with many of the overhaul procedures, modifications, and repair schemes applicable back to the war time engines.

 This set of data includes;

- Overhaul manuals, most models

- Bristol engineering instructions

- Packard service letters

- Modification manuals

- Reclamation & salvage data

- Parts books, most models

- Rolls Royce service bulletins

- Interchangeable parts list

In all, more than 70 books and manuals with very detailed information on overhaul, inspection, test, modifications, and repair of the Merlin engine. This data was accumulated by Rolls Royce and Bristol Aero Engines, over many years operating and overhauling the Merlin engines both in military and civilian transport aircraft. 

One example of this information, is a temperature investigation study, performed by Rolls Royce on the Merlin 600 series cylinder heads. The engineers drilled holes in the cylinder heads and inserted temperature probes, recording and charting the temperatures at various operating conditions on both new heads and examples with significant service time on them.

One of the findings concluded that the build up of corrosion and scale in the coolant jackets inside the heads, caused an increase in cylinder head temps from 70 deg C to 120 deg C, a very substantial amount.

We have repaired many cylinder heads in our shop that have suffered heat damage,  and upon inspection of the coolant jackets, found layers of scale and corrosion.  

Our findings, being consistent with the Rolls Royce data, led us to the decision to remove the core plugs from every cylinder head we bring in the shop, and grit blast the coolant jackets to clean metal as new condition, as just one of the standard overhaul procedures we perform on every cylinder head. This is a time consuming additional step, but we are confident it will provide a longer service life with less chance of compression loss due to heat damage.