Hangar 9 nut Posted July 27, 2014 Share Posted July 27, 2014 I have tried 3mm but are just a bit to small does this mean they are imperial size and if so what is it ! Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted July 27, 2014 Share Posted July 27, 2014 I think they are 3.5mm Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted July 28, 2014 Author Share Posted July 28, 2014 Thanks Bob I will try some! Quote Link to comment Share on other sites More sharing options...
onetenor Posted June 29, 2017 Share Posted June 29, 2017 If you mean the holes through the stub either side f cylinder the screw pass through these and screw into the silencer. They are indeed 3 mm screws /bolts I made same error . Nothing is intended to screw into those holes at all they are just clearance holes Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted June 29, 2017 Share Posted June 29, 2017 I am renovating a 40 FSR at the moment an the exhaust bolts screw through the silencer lugs into the crankcase. Unlike the FP and later engines where the bolts go through the c/case and screw into the silencer.They are older generation engines and the bolts are a coarse thread with imperial sized Allen head .All other screws on engine are metric. Â I will measure the thread tomorrow and get back Edited By Engine Doctor on 29/06/2017 22:46:03 Quote Link to comment Share on other sites More sharing options...
ERIC CLAPHAM Posted June 30, 2017 Share Posted June 30, 2017 The 40 FSR I have ( circa 1980) has two 3mm x 0.6 tapped holes either side of the exhaust port where the No.743 silencer screws on. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted July 1, 2017 Share Posted July 1, 2017 Checked them last night and the threads are 3.5mm .The screws I took out were the wrong thread but luckily haven't damaged the the thread in the c/case. Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted July 1, 2017 Author Share Posted July 1, 2017 Thanks engine doctor ! Quote Link to comment Share on other sites More sharing options...
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