Is it ok to hook up to the kill wire to just check spark timing on those motors where the flywheel would have to come off in order to disconnect the coil primary? If so, i'd like to try an ohmmeter where my poor eyes could still see a wide pointer swing instead of trying to see a slight dimming of the bulb or ears picking up when a horn changes pitch as the points begin to open with the coil secondary winding still in the circuit.
bill
Quick Timing Check
Moderator: Rob Voska
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Bill Hermsted
- Posts: 88
- Joined: Wed May 12, 2010 8:50 pm
- Vintage Karting items owned: 3 AH58's and 1 MC45
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Dick Teal
- Posts: 231
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- Vintage Karting items owned: 1959 Mak-Kart, 1960Fox 60L, 1961 Fox (2), 1962 Fox, 1963 Fox, 1964 Fox, Margay New Breed
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Re: Quick Timing Check
Bill,
I've never been able to check the timing the way you want to. My various ohm meters will not indicate when the points are opening by checking the resistance through the points. They work OK if the wire isn't going through the coil to ground but that means that the wire has to be disconnected. I have an old Radio Shack meter that has a swing needle and I do get a slight movement but not enough to feel good about.
I would guess that it's possible with some of the expensive meters available today but I never check the timing just to see what it is. I always want the flywheel off when I'm trying different advance settings at the track or when I'm building an engine.
I think the method you're trying is to just put one lead from your meter on the wire that comes from the points to the coil and the other lead to a ground on the engine like the fins or block. If not please explain.
I have a Timing Tester from the 60's made by Dunleer (model 761) that will work that way. It was developed for checking kart engines back when we were experminting with everything. It has a light and horn and that doesn't seem to work for you. I don't think that they're available today.
I find that it works best to go the whole way and use a degree wheel to find top dead center (TDC) and then put a mark on the flywheel and a line/mark on the side plate that line up. I use red fingernail polish or machinist bluing to paint the outside of the flywheel that I can scratch lines at 20 degrees, 25 degrees, etc. Once this is done I have a good way to get real accurate with the timing and I can change it fast. But if I'm going to change it I need to have the flywheel off on any of my McCulloch or West Bend engines so any ohm meter , continuity light etc. will work to check the points opening.
Dick Teal
I've never been able to check the timing the way you want to. My various ohm meters will not indicate when the points are opening by checking the resistance through the points. They work OK if the wire isn't going through the coil to ground but that means that the wire has to be disconnected. I have an old Radio Shack meter that has a swing needle and I do get a slight movement but not enough to feel good about.
I would guess that it's possible with some of the expensive meters available today but I never check the timing just to see what it is. I always want the flywheel off when I'm trying different advance settings at the track or when I'm building an engine.
I think the method you're trying is to just put one lead from your meter on the wire that comes from the points to the coil and the other lead to a ground on the engine like the fins or block. If not please explain.
I have a Timing Tester from the 60's made by Dunleer (model 761) that will work that way. It was developed for checking kart engines back when we were experminting with everything. It has a light and horn and that doesn't seem to work for you. I don't think that they're available today.
I find that it works best to go the whole way and use a degree wheel to find top dead center (TDC) and then put a mark on the flywheel and a line/mark on the side plate that line up. I use red fingernail polish or machinist bluing to paint the outside of the flywheel that I can scratch lines at 20 degrees, 25 degrees, etc. Once this is done I have a good way to get real accurate with the timing and I can change it fast. But if I'm going to change it I need to have the flywheel off on any of my McCulloch or West Bend engines so any ohm meter , continuity light etc. will work to check the points opening.
Dick Teal
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Bill Hermsted
- Posts: 88
- Joined: Wed May 12, 2010 8:50 pm
- Vintage Karting items owned: 3 AH58's and 1 MC45
- User Agreement: Yes
Re: Quick Timing Check
Dick-
my faulty brain spazzed out on this one. I tried timing with an ommeter from kill wire to a good ground. That big pointer swing i expected turned out to be a difference of only 1.5 ohms- probably the coil PRIMARY resistance. Good call! My whole idea was to just check and see if the timing crept any. I try to leave the flywheel on these PP's alone unless resetting or replacing points. You Mac guys are lucky that the coil is outside and the primary unplugs, and the puller holes are there. Hank told me to make a degree wheel, but for those with a dial indicator, here are the equivalents (for PP ah58's only)- 23 deg.= .092 piston position btdc, 24 deg.=.100, 25 deg.= .108, 26 deg.= .116, 27 deg.= .125, 28 deg.= .135. Thanks for making me think for once!
bill
my faulty brain spazzed out on this one. I tried timing with an ommeter from kill wire to a good ground. That big pointer swing i expected turned out to be a difference of only 1.5 ohms- probably the coil PRIMARY resistance. Good call! My whole idea was to just check and see if the timing crept any. I try to leave the flywheel on these PP's alone unless resetting or replacing points. You Mac guys are lucky that the coil is outside and the primary unplugs, and the puller holes are there. Hank told me to make a degree wheel, but for those with a dial indicator, here are the equivalents (for PP ah58's only)- 23 deg.= .092 piston position btdc, 24 deg.=.100, 25 deg.= .108, 26 deg.= .116, 27 deg.= .125, 28 deg.= .135. Thanks for making me think for once!
bill