Greentored 3,220 #1 Posted August 17, 2020 Just a random topic for discussion and curiosity's sake. This one in particular my 1277 'lawn duty'. Engine is in a great state of tune (zero oil use since changed, maybe 20hrs) Trans is a C120 Sundstrand unit. That hydro unit really loads the engine when engaging the belt, especially cold (ambient). Fluid is 10w30. Tractor runs and mows great, but just seems like its 'working' a lot. Governor is adjusted correctly and does not lose rpm. Is this just 'nature of the beast' with these? My bronco 14 is a touch on the tired side and does it too, but not like the 1277. Certainly wouldn't think that extra 2hp makes that much difference, or does it? Whatcha think? Share this post Link to post Share on other sites
Mike'sHorseBarn 3,271 #2 Posted August 17, 2020 Following along to get an education Share this post Link to post Share on other sites
Ed Kennell 42,186 #3 Posted August 17, 2020 Some "experts" feel a Sundstrand requires about 3HP to move a tractor. This leaves you with 9HP and 11HP to turn the blades. That's 22% more available HP on the Bronco 14 for turning the blades. 2 1 Share this post Link to post Share on other sites
pfrederi 18,714 #4 Posted August 17, 2020 My Sunstrands pull down the K301 and the Techy HH100 when you engage the drive but they recover ...Unless it is really cold then you have to be careful and slowly engage the drive. All mine run ATF. 1 Share this post Link to post Share on other sites
Stepney 2,354 #5 Posted August 17, 2020 How's your timing? I used to run a B100 years ago that wouldn't pull a hill running a deck. Hydro and a 10 horse plus a 36"RD would kill it.. long story short points were way out. Was still slow but much much better than it had been. 2 1 Share this post Link to post Share on other sites
953 nut 60,356 #6 Posted August 17, 2020 I was thinking the same thing. Your ignition points set the ignition timing and if the timing is too late the engine will start fine and run OK without a load but power is reduced. 2 Share this post Link to post Share on other sites
Greentored 3,220 #7 Posted August 18, 2020 Ya know, sitting here thinking- I never verified/adjusted the timing on this one- threw a set of points in when I got it this past spring, eyeballed em, and have been running the wheels off of it. I do know governor adjustment and moving the springs around made a HUGE difference- that stopped the rpm loss.... Anyone ever try synthetic in these old Sundstrands? Does it help? Share this post Link to post Share on other sites
tom2p 2,394 #8 Posted August 18, 2020 the viscosity of the fluid can make a difference - but don't know how much 1 Share this post Link to post Share on other sites
Greentored 3,220 #9 Posted August 19, 2020 Once again you fellas hit the nail on the head! I forgot the golden rule: KISS- "keep it simple, stupid". Ignition timing checked with an ohm meter for points break- timing was dang near right on TDC instead of 20! Now heres the odd part: at 20 degrees, the response and power are day and night, but it rattles like a SOB- like, scary. I decreased timing in increments to no avail, rolled it over til the points were at their widest spot, set with feelers to .020 and no rattle, but power is not like it was at meter verified 20. TDC and 20 verified, so no flywheel slip issue. Any ideas? Its on plain old 87 octane. Maybe start running 93 in these machines and pour the timing to em? Share this post Link to post Share on other sites
squonk 43,944 #10 Posted August 19, 2020 Maybe de-carbon the combustion chamber 1 Share this post Link to post Share on other sites
prondzy 3,889 #11 Posted August 19, 2020 A hydro transmission will rob at least 30% of hp due to the pump turning, cold fluid will only make a pump turn harder. Share this post Link to post Share on other sites
Greentored 3,220 #12 Posted August 20, 2020 @prondzy that is exactly what it 'acts' like. Think i'll yank the head and decarbon, lash the valves, put the timing light on it this go round and chalk it up to 'normal operation'. Will post up the results for others with questions to reference. 1 Share this post Link to post Share on other sites
953 nut 60,356 #13 Posted August 20, 2020 13 hours ago, Greentored said: put the timing light on it this go round Static timing should work but a timing light is the way to go. 1 Share this post Link to post Share on other sites
ebinmaine 73,002 #14 Posted August 20, 2020 On 8/17/2020 at 2:43 PM, Mike'sHorseBarn said: Following along to get an education Me too.. Share this post Link to post Share on other sites