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Author Topic: SC91FS Valve Clearance  (Read 664 times)

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Offline discus.fly

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SC91FS Valve Clearance
« on: June 30, 2017, 16:55:04 PM »
Can anyone please advise the correct valve clearance for a SC 91 FS?


Offline FlyinBrian

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Re: SC91FS Valve Clearance
« Reply #1 on: June 30, 2017, 18:21:15 PM »
I have an ASP 91 FS which is the same engine, the instructions do not give any details of valve clearance.
Typically 1 to 4 thou is quoted by some engine manufacturers. OS actually supply a feeler gauge for this purpose but I have not had an OS for a few years.

You could ask Just Engines.

Or check this - https://www.youtube.com/watch?v=WPj80SGPdto
« Last Edit: June 30, 2017, 18:23:21 PM by FlyinBrian »
Basic Research is what I do - when I don't know what I'm doing!.

Offline discus.fly

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Re: SC91FS Valve Clearance
« Reply #2 on: June 30, 2017, 19:07:54 PM »
Brian, does yours make a clicking sound when turned over when hot?


Offline FlyinBrian

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Re: SC91FS Valve Clearance
« Reply #3 on: June 30, 2017, 20:40:43 PM »
I have not noticed any clicking DF, got to be worth checking the tappets.
Basic Research is what I do - when I don't know what I'm doing!.

Offline discus.fly

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Re: SC91FS Valve Clearance
« Reply #4 on: July 01, 2017, 18:03:17 PM »
Tappets adjusted using 3 thou feeler gauge and found the engine runs very well both forwards and backwards!  Never done that before but it least its starts very well and does not stop in the air so it must be good.


Offline discus.fly

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Re: SC91FS Valve Clearance
« Reply #5 on: July 07, 2017, 16:30:38 PM »
Well its all gone a tadge worse. One tappet has sheared and pushed itself through the upper cover. Surprisingly it still ran!  Who services these engines in the UK?
« Last Edit: July 07, 2017, 17:57:10 PM by discus.fly »

Offline jrman

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Re: SC91FS Valve Clearance
« Reply #6 on: July 07, 2017, 17:47:57 PM »
Just Engines will repair / service it and do an excellent job. They have all the appropriate hammers. :''

Offline discus.fly

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Re: SC91FS Valve Clearance
« Reply #7 on: July 07, 2017, 17:59:45 PM »
Thanks have already sent them a mail.  Looking at the parts it looks a simple repair, so will try and see if I can do the job myself.  All I need is the rocker box cover and the adjustment screw.
« Last Edit: July 07, 2017, 18:01:04 PM by discus.fly »

Offline FlyinBrian

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Re: SC91FS Valve Clearance
« Reply #8 on: July 07, 2017, 20:17:55 PM »
J Perkins are the distribution / service agent  but if it is o o warranty I'd go with J E.

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Offline discus.fly

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Re: SC91FS Valve Clearance
« Reply #9 on: July 08, 2017, 18:05:28 PM »
Are ASP parts the same as SC?

Offline jrman

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Re: SC91FS Valve Clearance
« Reply #10 on: July 08, 2017, 23:07:30 PM »
As far as I am aware they are identical except for the name on the crankcases and the boxes they come in. They are made in the same factory.

Offline clive_f

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Re: SC91FS Valve Clearance
« Reply #11 on: July 11, 2017, 17:30:09 PM »
jrman is quite correct   ASP, SC and Magnum are all made in the same factory in Schennzen.

The parts are interchangable and as said by several posters  JE is the place to go.

No link just satisfied and wish they were still up here in Cumbria!

Clive

oh and the gap is the same as OS 0.1 - 0.2 mm COLD @ TDC   which in old money is 2 - 4 thou as stated by Brian.

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Offline discus.fly

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Re: SC91FS Valve Clearance
« Reply #12 on: July 18, 2017, 16:44:00 PM »
Well, parts replaced but it just gets worse.  Valves are now operating but there is zero compression.  Assume the crank must be sheared or possibly a broken valve.

Offline trebor

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Re: SC91FS Valve Clearance
« Reply #13 on: July 18, 2017, 17:03:22 PM »
Did you adjust your valve clearances with the piston at top dead centre, if you did it on the exhaust cycle the valves may be slightly open on the compression stroke.
Hope you get to the bottom of it.

Offline discus.fly

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Re: SC91FS Valve Clearance
« Reply #14 on: July 18, 2017, 17:51:23 PM »
Problem was a valve issue. Once the glow plug was removed I could see the piston was moving so removed the valve rocker bar and depressed each valve by hand.  Refitting the glow plug gave compression again so re-installed the valve rocker bar with both tappets screwed in.  Success, now have compression again, so looks like the problem is fixed.


 

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