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The Marston Sunbeam Club & Register Forum

General Category => Technical Discussion Forum => Topic started by: Tommy cooper on March 31, 2020, 12:57:41 PM

Title: Side valve 500cc valve timing
Post by: Tommy cooper on March 31, 2020, 12:57:41 PM
Can anyone give me the correct valve timing for a 500 side valve engine
thanks TC
Title: Re: Side valve 500cc valve timing
Post by: singleminded on March 31, 2020, 07:26:17 PM
It's gonna depend on what cams you have..Any marks on them?
Title: Re: Side valve 500cc valve timing
Post by: Tommy cooper on April 01, 2020, 12:50:39 PM
The cams on the Sunbeam are marked FJ..the bike is a 1927 500cc sidevalve
thanks TC
Title: Re: Side valve 500cc valve timing
Post by: singleminded on April 01, 2020, 02:04:29 PM
Tommy, do you have the Autumn 2015 copy of Beaming?
The cam timings are listed on page 13..
FJ cams are :-  0 - 60 /60- 17..I assume that means that the inlet opens at TDC and closes 60 ABDC and the  exhaust opens 60 BBDC and closes 17 ATDC..
Are your dots missing?
Title: Re: Side valve 500cc valve timing
Post by: Tommy cooper on April 01, 2020, 02:37:48 PM
That's the timing that is being used at the minute,the bike starts and runs,And I realise that better men have built engines before but felt that more over lap on the inlet  valve.
Thanks for the reply
TC
Title: Re: Side valve 500cc valve timing
Post by: phutton on April 02, 2020, 10:59:04 AM
Some people have fitted the 30-60 cams, as used on the 1928-on M90s, to their M6s. inlet 30 btdc/60abdc - ex 60bbdc/30atdc. I've no experience of this, but others might like to report back!
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