SOHC 350cc 40M 1935-48 (Magnesium Crankcase) Front Engine Plates - Pair

Product no.: 0202 A10M/522

In stock

£58.00
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These front engine plates are for Pre-1948 350cc 40M/Manx models, using magnesium crankcases, and are fabricated using sided jigs (see pictures), to ensure they have the correct offset, form and hole location as original engine plates. All dimensions are copied from an original SOHC 350cc Manx engine plate

Background information:  Genuine Pre-Featherbed Norton racing models (from approximately 1935 onwards) used magnesium crankcases and had a different front engine mount on the frame downtube on both rigid and plunger models.  The front downtube engine mount on these frames sat approximately one inch (1") higher than their aluminium crankcased road going (International) SOHC counterparts.  Therefore these different type engine plates were required. 

Added to this, the magnesium (40M or early Manx) crankcase also had wider engine plate mounts at the front of the crankcase than aluminium International crankcases - that necessitated the engine plates being manufactured with a 'kink' in their sides, so they came in at the front to match the frame downtube lug. 

We have our engine plates lasercut - having used an original 40M (SOHC Manx) engine plate as the template - but we then have specially made jigs to allow them to be formed to the correct shape and profile - before the front engine bolt hole is then bored to the correct dimension on the jig.  This ensures these plates are always the correct dimensions. See accompanying photos

Finally, we lightly linish the edges (to remove any lasercutting marks) and lightly oil them to protect them from rust, before packing.  Price is for a pair of engine plates.

Final point for these 350cc (40M) models - the 350cc 40M model used a crankcase that was physically slightly smaller than the 500cc 30M model (we also sell engine plates for that model - Item 0201) - therefore the engine plates shown here are different to the 500cc model.  However, sometime around 1948 Norton standardised the racing models on the 500cc type crankcase for both capacities - just having a smaller cylinder hole bored in the 350cc crankcases.  If you have a later set of pre-Featherbed 350cc Manx crankcases and are not sure which type they are - email us on sales@racingvincent.co.uk and we can help confirm for you.

In the accompanying photographs is a picture of a genuine (1936) Manx engine with one of these engine plates attached, and an original pre-war photograph of a 350cc 40M (Manx spec), which shows the engine plate - distinctive from the 500cc version in that its top face slopes down towards the engine, while the 500cc top face of the engine plate is horizontal

 

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