Tue Jul 12, 2011 8:39 am
While rebuilding the water pump, governor, steering and radiator on the 140 last year, I discovered that the distributor advance weight springs had crumbled. Time dictated letting that go until now. The lack of controlled spark advance does adversely affect the performance. Now I have the springs, very expensive. Two springs, but also very different from each other. They came in the sealed pack from the dealer, so one assumes that they are correct. No manual I have gets into the details of the springs. Is it evident in the distributor which spring goes where?
Any advice on making certain that they are installed correctly?
I have done lots of Chevy V-8 distributors from the 1970s but those springs are in matched pairs.
Tue Jul 12, 2011 11:55 am
I've never seen a distributor where the 2 advance springs were not identical. But I don't know for a fact that they always are. The shaft and weights where they attach are symetrical. So if the difference is correct, it shouldn't matter which goes where. My inclination is to think the springs were mis-packaged. I'd like to see another sealed package of the same part number. Two different distributors were listed for the 140, code AB on the earlier and code T on the later. Code T has less advance.
Tue Jul 12, 2011 3:29 pm
Mine is the AB. The springs are 372785R91. That number is on the inner and outer packaging. Genuine packaging beyond any doubt. One of the springs has 4 coils and the other has 7 coils. The overall length of both springs is the same and correct for the distributor. The inner pack is marked CNH Global N.V. PN-272785R91. The outerpack is marked made in USA. The new are lighter gauge wire than the old, but I had no measuring means at hand while changing them. The tractor seems to run ok, but has not yet been run under load.
On the Chevys, we sometimes used one lighter and one heavier spring to get the centrifugal advance to begin at lower engine speeds.
Wed Jul 13, 2011 7:20 am
While I'm not familiar with the 140 dist. I have seen other make dists. with two different springs. I'm guessing they'll work just fine.
Fri Jul 22, 2011 10:26 am
Bus Driver, Quite awhile ago I was doing some research on the IH 4 cylinder distributors. From what I could gather, the C60, the C115(?) and C120(?) all had identical IH distributors except for the main distributor part number and the individual advance spring numbers. Even the centrifugal weight numbers were all the same for all the IH distributors of that era. What I am saying is that the only difference that IH did between all of those distributors was to change the springs.
I am going to be getting back into that area soon though because I recently found out that engines running at high altitude require much more 'total advance' than those at sea level. My son has a C60 in a Cub Loboy 184 running at 7,300 foot elevation (25% less oxygen). After 2 years of tinkering, I have only the timing to go. So far have shaved .080" off of the cylinder head (go back at least 10% of lost HP). Zenith carb, went from #21 main jets down to #19, and idle jets from #12 down to #10 (both idle mixture and power mixture are both 'right-on' by spark plug examination). Now on the timing to work on.
Scientifically; at altitude, the combustion chamber mixture has a MUCH slower 'burn rate' - so, the peak cylinder peak pressure is actually occurring way after TDC if the original advance settings are not changed to compensate for 'high altitude'. I am making a calculated, educated guess that at 7,300 feet it need an additional 4 to 8 degrees of total advance (20 to 24 total for the C60 engine). Of course, since the IH distributor is limited at 16 degrees advance (by the weights hitting the stops) the base timing will move from 0 degrees to 4 or 8 degrees. The starter motor may still be able to crank the engine at that advanced initial timing (cylinder compression is still low due to the 'thin air'). If the starter won't crank it properly, then 'notch filing' of the weights will have to be experimented with in order to increase the total range that the weights can move the advance plate.
Fun, fun, fun, NJDale
Fri Jul 22, 2011 12:19 pm
b52c130 wrote:From what I could gather, the C60, the C115(?) and C120(?) all had identical IH distributors except for the main distributor part number and the individual advance spring numbers. Even the centrifugal weight numbers were all the same for all the IH distributors of that era. What I am saying is that the only difference that IH did between all of those distributors was to change the springs.
If the starter won't crank it properly, then 'notch filing' of the weights will have to be experimented with in order to increase the total range that the weights can move the advance plate.
. Different distributor shafts were used to set maximum advance in different versions of the distributor. Each shaft was stamped for rotation and maximum advance. You can file on the weights all day and it will have no effect on the total advance.
Sat Jul 23, 2011 8:31 am
I often do not confess my "transgressions" from the stated norms for fear of leading others to do "BAD" things. I have a distributor Cub with full throttle timing advanced 4 deg beyond specs and I assume that it is cranking with the 4 deg advance. Too much advance at cranking is asking for trouble, especially with a hand crank. My tractor seems to like the extra advance at about 1500 feet above sea level.
Wed Jul 27, 2011 9:52 am
"Thank you" to Jim Becker - when I get deeper into the 'more advance' issue with the high altitude C60, you have given me a good 'pointer' on what area to focus my research on to get a different part to get the additional required advance. Most of my 'advance curve' modification experience has been with GM HEI distributors and they do it with the weights. Thanks again, NJDale
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