Misc: Everything Else 1951 Black Shadow Restoration
- Thread starter craig
- Start date
One keyway on the 1/2T pinion is 360 deg divided by 24 teeth divided by 5 keyways= 3 degrees.
So if you are looking to have = lift at 4deg before TDC, one keyway will give you 3 degrees which in anyone's book agrees with your last option. Close enough!
So if you are looking to have = lift at 4deg before TDC, one keyway will give you 3 degrees which in anyone's book agrees with your last option. Close enough!
That 1/2 time pinion is why I like to set up my engine in reverse. Best explained on a comet, set up the engine valves at equal lift (sitting the cam slot between the push rod tubes is a good start) lock the cam using a washer and a screw in one of the timing cover holes.remove the 1/2 time key (i have one with a' handle' i can pull out behind the timing disk.) rotate the engine to 4degrees BTDC and remove the timing disk now simply lift and replace the 1/2 time pinion until you find a exact match or nearest match of keyway move crank slightly if necessary pop in key, unlock cam, check out setting, if you are lucky you are spot on!
a great big timing disk mounted on the ESA makes it very easy to see EXACTLY where you are. For valve timing (during a rebuild) I do it BEFORE I fit the head by looking for equal lift at the valve lifter cups - that way there is no 'fighting' the valve springs. If the head is in place then I remove the pushrods and use 'extension' rods so again, no valve springs to deal with and measure at the valve lifter cups.
You can do the ignition timing the same way
But first use a piston stop to find TDC!
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I had a large idler with a like problem. First task is to see the problem. Is the centre out of position OR is the idler not round? In my case the idler was round but the centre was NOT in the centre
An old time machinist fixed it for me. Involved enlarging the centre then fitting a cast iron bush then machining the bush central. He used a 4 jaw chuck with 'wires' fitted into the valleys of the idler to get it central before he bored the centre to size.
Took a while but resulted in less than 0.003" runout.
An old time machinist fixed it for me. Involved enlarging the centre then fitting a cast iron bush then machining the bush central. He used a 4 jaw chuck with 'wires' fitted into the valleys of the idler to get it central before he bored the centre to size.
Took a while but resulted in less than 0.003" runout.
Why wouldn't you shim the large idler.?
you either have to shim the lot for proper end float OR use a slide hammer to adjust the exposed spindle length. I look for .006 end float on the cams.
Re that timing disc with all the racing and other things I have not had time yet for a pet project I bought one of these a digital inclinometers for a few quid and as soon as I can:
My plan is to make a platform like this (steel for magnetic base)
fitting this to the crank shaft with gage in place put piston aprox TDC and press set zero button do the backwards and forwards stop routine till TDC found. Press zero again no pointer to worry about no hulking big dial.....
What have I missed?
My plan is to make a platform like this (steel for magnetic base)
What have I missed?
If you have access to a smart phone or tablet there is an app, called 'level' on mine which is free. It resolve to 0.1 degree but whether it has that accuracty I dont know.