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1930 Model 18 Valve Timing

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Hi All,

I am rebuilding a 1930 model 18 motor for a friend and wanted to confirm what the valve timing specifications are.

I have a book called Motor Cycling maintenance series Norton motorcycles 1928-55.

In the data section it says Model 18 1928-1931 compression ratio-6.0-1

Valve timing- Inlet opens 1/4" BTDC

                     Exhaust closes 1/4" ATDC

Ignition Timing 1/2" BTDC Fully Advanced

Tappet Clearance Cold  Inlet/Outlet 0.003 

Can anybody confirm that this is correct.

Cheers

Andy

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Andy, 

My 1930 Norton Maintenance manual lists the following data:

Exhaust opens 0.75" (or 55-60 degrees BBDC).

Exhaust closes 0.25" (or 25-30 degrees ATDC).

Inlet opens 0.25" (or 25-30 degrees BTDC). 

Inlet closes 0.4375" (or 40-45 degrees ABDC). 

Tappet clearance is 0.003" for both inlet and exhaust valves. 

 

Agree with Andy as above but mine was really hard to start so l set ignition timing at 5/16 BTDC. With a bit of choke now and a few purgr kicks after a flooded carb with lifter in she starts first time...trial and error each one is slightly different

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sounds very late. My 1952 (which would I think be broadly similar) does very well at the specified 5/8" ignition advance. Starts first kick on half retard with air lever closed (and no flooding in warm weather).

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I agree with Ian. Why not set it to 5/8 and also mark the lever at 5/16. Too far retarded and it will be sluggish and hot.

 


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