21-09-2018, 10:19 AM
Timing gears......I think the usual check is to use feeler gauges to check the backlash between the teeth, both sides.
For example when getting new timing wheels for my Ford engined Reliant Scimitar one of our engineer suppliers used to ask for those readings and he would supply one of THREE different sizes he had made and in stock. This was to allow for any variation between the centres being bored during manufacture. (for example the Ford backlash allowed in my V6 3 lit is 0.007" to 0.011 inches). The 4 (8) required measurements were asked to be taken at 90 degs. of rotation to each other.
The cam and crank centres may vary in distance apart; the gear may not be concentric......
My backlash measured at 0.009" with the new timing gears in the Ford engine and they are nice and quiet.
As said above the 7 gears were selectively assembled in pairs and marked as pairs. (someone somewhere suggested that Austin 7 engineering was simple basic non precision .......don't you believe it.....they knew what they were doing and were mostly good at it.)
Does anyone have the official backlash figures for the 7 engine.?
For example when getting new timing wheels for my Ford engined Reliant Scimitar one of our engineer suppliers used to ask for those readings and he would supply one of THREE different sizes he had made and in stock. This was to allow for any variation between the centres being bored during manufacture. (for example the Ford backlash allowed in my V6 3 lit is 0.007" to 0.011 inches). The 4 (8) required measurements were asked to be taken at 90 degs. of rotation to each other.
The cam and crank centres may vary in distance apart; the gear may not be concentric......
My backlash measured at 0.009" with the new timing gears in the Ford engine and they are nice and quiet.
As said above the 7 gears were selectively assembled in pairs and marked as pairs. (someone somewhere suggested that Austin 7 engineering was simple basic non precision .......don't you believe it.....they knew what they were doing and were mostly good at it.)
Does anyone have the official backlash figures for the 7 engine.?