Gear drive runout?

[Dunc the Funk]

Hiya, just checking some stuff before re-assembly. Last year we had the cam dowel come out & I found that the hole in the gear drive cam hub was oversize. I removed the cam, drilled the cam hole larger then reamed it & the hub larger, fitted a bigger dowel & it ran ok. I thought I really ought to look at gear backlash & runout while I have time & the motor is fully apart. Rotating the crank & cam with the gear drive bolted down shows no tight spots but the backlash does change a bit during rotation. I removed the cover again to check runout on the cam gear. It's a maximum of 4 thou (or +2 to -2). Anyone know if this is ok?

[dreracecar]

When setting up my 3 gear Summers Bros drive, I took 2 strips of notebook paper, folded them in half and rotated them between the gears and then tightened the idler, removed the paper and the backlash is set, never an issue. This method came direct from one of the top sprint car engine builders of USAC and WOO 410. Gears only see load in 1 direction anyway so it really does not matter as long as there is no binding in the gears