- Fri Oct 26, 2012 8:24 am
#1365
Hello All,
setting the timing by trying to get top dead centre then back 1/32 or whatever the correct amount given for the retarded setting is not very accurate the crank can move about 5 degrees without the piston moving when at TDC because the crank pin is moving across the top of its arc. I have checked this with a engine on the bench. Set once using a degree disc at full advance.
When you know the timing is spot on and engine is fully assembled, get a top
dead centre tool that screws into the spark plug hole and machine it, so that
when it is fully down it touches the piston at the correct firing point.
Then to check or re set ignition just bring piston up to touch it. A finger can
just feel it touching. and with a thin feeler or paper you can check or set the
timing.
This is good when on holiday and you get problems. I did it at the Manx and
within 5 minutes I knew my ignition was spot on. I have done this on the bench
with a degree disc to check if this method is good and found it a very accurate
method.
Or just put the a spacer on the centre part of the timing tool that is the correct advance figure. Reduce the TDC tool until it just touches piston at TDC then remove spacer and the tool should now project into cylinder the correct amount. Bring piston up to just touching and bingo it is in the correct position for setting the timing at full advance, BUT. This second option is only accurate if a vertical Spark plug hole is used. It needs an allowance for the angle of the plug hole in relation to piston movement, any one know how to work this out?
Have fun.
Mikey
setting the timing by trying to get top dead centre then back 1/32 or whatever the correct amount given for the retarded setting is not very accurate the crank can move about 5 degrees without the piston moving when at TDC because the crank pin is moving across the top of its arc. I have checked this with a engine on the bench. Set once using a degree disc at full advance.
When you know the timing is spot on and engine is fully assembled, get a top
dead centre tool that screws into the spark plug hole and machine it, so that
when it is fully down it touches the piston at the correct firing point.
Then to check or re set ignition just bring piston up to touch it. A finger can
just feel it touching. and with a thin feeler or paper you can check or set the
timing.
This is good when on holiday and you get problems. I did it at the Manx and
within 5 minutes I knew my ignition was spot on. I have done this on the bench
with a degree disc to check if this method is good and found it a very accurate
method.
Or just put the a spacer on the centre part of the timing tool that is the correct advance figure. Reduce the TDC tool until it just touches piston at TDC then remove spacer and the tool should now project into cylinder the correct amount. Bring piston up to just touching and bingo it is in the correct position for setting the timing at full advance, BUT. This second option is only accurate if a vertical Spark plug hole is used. It needs an allowance for the angle of the plug hole in relation to piston movement, any one know how to work this out?
Have fun.
Mikey
