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Engine basics => Engine set up tips => Topic started by: Motorman on September 13, 2018, 07:40:40 PM

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Post by: Motorman on September 13, 2018, 07:40:40 PM

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Title: Re: Intake Timing
Post by: RandySmith on September 13, 2018, 09:52:00 PM

135 145 degrees  sleeve timing   190 crank timing

many stunt engines , people  use ,  will  run  from 125 degrees  to 150
and  crank timing  from 180  to 200  degrees

Randy

Title: Re: Intake Timing
Post by: Lauri Malila on September 13, 2018, 11:37:49 PM

Randy,

Can you give a typical conrod lenght:stroke ratio of your engines.
I'm asking because if the mechanical geometry is not same, comparing timings (in degrees) is quite inaccurate.
I'd rather look at timings as percentage of stroke.

Cheers, Lauri

Title: Re: Intake Timing
Post by: M Spencer on September 14, 2018, 07:41:32 PM

olde dungers like a Merco , with tiny round port and case port can be something like 45 - 45 .

Later the intake closes the more itll let it rev .
Parently the Mk III Rossi was a bit late at 62 , so could be awkward to restart in goodyear .

Typcal stunt ' Tourquer ' might shut aroud 45 or 50 .

A load or compete tripe , I should think . Being as stock theyre fine . But heres some drivle to peruse .

http://www.machineconcepts.co.uk/aeromodelling/st51/st51-1.htm#shaft

Seems hes sleeving down the shaft bore , The Olde ' increase the gas speed ' trick .

Like woton Rally Cars , where the smaller zorst tubing gets better throttle respose . Circuit and you go oversize for top end . Thar she blows .