HilltopXJ
NAXJA Member #950
- Location
- Eagle Point, OR
Anyone know the backlash tolerances for the distrubutor gear?
thanks
thanks
-
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distributor gear
- Thread starter HilltopXJ
- Start date
FUNKYTEE5
NAXJA Forum User
- Location
- Vancouver, Wa.
I think that backlash on the dist. gear isn't really measured to a certain spec. The acutal wear on the cam/distributor drive gears is more important. Thats my thoughts.
5-90
NAXJA Forum User
- Location
- Hammerspace
I've just checked a large handful of manuals, and I'm not seeing a spec for this.
Generally, I check to make sure that I can't turn the rotor more than, say, three to five degrees by hand (I know that sounds like a lot, but the distributor only turns in one direction, and that can be a little more forgiving) and that I can't lift the rotor straight up by more than about .010"-.015" (it's OK if it twists while you do this - you're checking endplay, and the helical gear is going to force a turn. I'm more worried if it DOESN'T try to turn!)
Also, make sure there isn't a lot of side play in the distributor shaft (more than .003-.005", checked with a dial indicator, like anything else important) - which indicates worn bushings.
The gear alone can be changed, and I tend to prefer bronze where available - I'm just cranky that way.
Most distributors can accept new bushings, but I've not seen any about for the 242. It is probably necessary to change the entire distributor for worn bushings - but I hope not. Care must be exercised while changing distributor shaft bushings - it's easy to screw this up.
Please note that ignition timing "walk" can be caused either by wear at the distributor drive gear, or by timing chain stretch. To check the latter, turn the crankshaft anticlockwise about 15 degrees, mark the (normal) leading edge of the distributor, and turn the crankshaft forward. While a little slack in the chain is normal (again, it only turns one way in operation,) you shoudn't be able to turn more than 5-15 degrees before the distributor begins to move. You turned it backwards slightly to "unload" the chain, and put the slack where you have to take it up before you can move, which allows you to evaluate chain tension.
I'd not worry about either of these checks unless I'd previously checked timing with a timing light, and I couldn't get the mark to settle down enough to read the thing consistently...
5-90
Generally, I check to make sure that I can't turn the rotor more than, say, three to five degrees by hand (I know that sounds like a lot, but the distributor only turns in one direction, and that can be a little more forgiving) and that I can't lift the rotor straight up by more than about .010"-.015" (it's OK if it twists while you do this - you're checking endplay, and the helical gear is going to force a turn. I'm more worried if it DOESN'T try to turn!)
Also, make sure there isn't a lot of side play in the distributor shaft (more than .003-.005", checked with a dial indicator, like anything else important) - which indicates worn bushings.
The gear alone can be changed, and I tend to prefer bronze where available - I'm just cranky that way.
Most distributors can accept new bushings, but I've not seen any about for the 242. It is probably necessary to change the entire distributor for worn bushings - but I hope not. Care must be exercised while changing distributor shaft bushings - it's easy to screw this up.
Please note that ignition timing "walk" can be caused either by wear at the distributor drive gear, or by timing chain stretch. To check the latter, turn the crankshaft anticlockwise about 15 degrees, mark the (normal) leading edge of the distributor, and turn the crankshaft forward. While a little slack in the chain is normal (again, it only turns one way in operation,) you shoudn't be able to turn more than 5-15 degrees before the distributor begins to move. You turned it backwards slightly to "unload" the chain, and put the slack where you have to take it up before you can move, which allows you to evaluate chain tension.
I'd not worry about either of these checks unless I'd previously checked timing with a timing light, and I couldn't get the mark to settle down enough to read the thing consistently...
5-90