560 Gas Rough Idle

Gavin Ahlbrecht63560D · Jun 20, 2015

My son and I just put the 560 head on and started it up last night. We adjusted the valves using the 1,2,3,5,7,& 9 at #1 piston at TDC and the rest with #6 at TDC. The tractor seems to run a little rough, kind of a miss. When you pull the throttle back, the tractor climbs in RPMs without miss. It doesn't idle as smoothly as our 460 gasser. We put new plugs in it and worked on the timing, still seems to run a little rough. What else can I do to make the 560 run smoother? Am I being to fussy with the way it runs? Thanks.

pete 23 · Jun 20, 2015

Check for air leaks at intake manifold. There are two different styles of manifold gaskets used and you have to use the same style unless you split the manifold so it can realign it's self. Any penetrating oil, propane torch unlit moved along the intake at head will show up a leak if engine runs faster or smoother. If that fails, might want to recheck valve clearance as not unusual for things to settle in after starting engine. I don't like that method of only two positions of crankshaft. I go down firing order and adjust each cyl at top dead center compression. Reason being is that engine uses a considerable amount of ramp on the cam lobe long before it actually starts to open valve and if you adjust each cyl separate you at least get that ramp in the same position for all cylinders. IH service schools told us we had to use the simplified method, I said, no I don't.

rustred · Jun 20, 2015

i agree with pete on the valve adjustment. each cyl. separate. also using a feeler guage takes experience. to check yourself add the next .001 higher and it should not go between rocker and valve stem.

Andy Martin · Jun 20, 2015

What do you mean "should not go between rocker and valve stem"? Because you have 0.001" extra?

Make sure there is not a step worn in the rocker where it contacts the valve stem. The end of the rocker arm needs to be ground smooth to use feeler gauges.

I have been successful when the rocker arm is worn using a wire gauge or by cranking the adjustment down until there is zero clearance (spin the push rod and you can tell when you hit zero) then back off the adjustment based on thread pitch. This can take care of sloppy rocker arm bearing fit as well.

Gavin Ahlbrecht63560D · Jun 20, 2015

Thank you all for your input. We re-torked the head bolts and re adjusted the clearance on the valves. We also found an intake leak using the acetylene method. She now runs very, very smooth. Good to have my chore tractor back!

560 Gas Rough Idle

Gavin Ahlbrecht63560D

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pete 23

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rustred

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Andy Martin

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Gavin Ahlbrecht63560D

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