Export thread

I was watching some youtube vids on adjusting the valves on mower engines. I saw one guy that just rotated the engine until he saw the exhaust valve go fully open and then adjusted the intake and then did the reverse intake fully open and adjusted the exhaust. my manual for the motor says to find tdc on compression stroke and then adjust both. It would be easier to do the fully open method that the guy did in the video (no disassembly to see timing) and seems to be ok in my limited experience with it - what do you guys think>>

natedawgk1972 said:

I was watching some youtube vids on adjusting the valves on mower engines. I saw one guy that just rotated the engine until he saw the exhaust valve go fully open and then adjusted the intake and then did the reverse intake fully open and adjusted the exhaust. my manual for the motor says to find tdc on compression stroke and then adjust both. It would be easier to do the fully open method that the guy did in the video (no disassembly to see timing) and seems to be ok in my limited experience with it - what do you guys think>>

Click to expand...

If disassembly means removing the spark plugs and it seems easier to you do it that way if it works.

I find it easier to rotate the engine by hand with the plugs removed and according to the safety manual the plug wires should already be off.

I hope that guy never has to set valves on a 12 cylinder that way when it's rotated with a 1/2 " ratchet and can be done in 2 revolutions of the engine. He would be cranking a ratchet for a long long time.lol

by disassembly i mean taking the cover off to see the flywheel/coils. in the manual it has you do it that way to see where tdc on the compression is for each cylinder so both valves are closed and thus you can adjust both at same time. If i can just watch the valves as i turn the motor until the exhaust/intake valves open all the way i could adjust the opposite one as it would be closed all the way??? as i write this it occurs to me "how will i turn the motor?" - I guess I would have to remove cover anyway to turn it?? I'm not against removing it, it's not that hard but if I can do it more simply obviously I would like to do it that way and more frequenty say once a season.

If the spark plugs are removed you should be able to rotate with the filter screen on top of the engine by hand. Never heard of disassembly to see the coils. That would require removing the air shroud.

Thanks for the picture, but from what I can see they have complicated a very simple procedure.

If I lived near by I'd come adjust the valves on your engine for free every year. I say free, but possibly a cup of coffee if in the morning and if PM a glass of tea.

I do perhaps make more of a job than necessary, but I remove the shroud on my Intek. I have put a little punch mark at TDC . I turn the fly with the big hex. Only takes a minute. But it seems the "probe" should work well (piston 1/4" down on compression). The so called base circle on the cams are uniform over a large radius so the lash reading will also be accurate. If your mfgr has put TDC marks on I would use them. ( I tried to read the text you sent, but too blurry)

natedawgk1972 said:

I was watching some youtube vids on adjusting the valves on mower engines. I saw one guy that just rotated the engine until he saw the exhaust valve go fully open and then adjusted the intake and then did the reverse intake fully open and adjusted the exhaust. my manual for the motor says to find tdc on compression stroke and then adjust both. It would be easier to do the fully open method that the guy did in the video (no disassembly to see timing) and seems to be ok in my limited experience with it - what do you guys think>>

Click to expand...

Both methods are correct.
The first method gets used when you do not know what the cam grind is because by doing it this way you can not get the timing wrong.
Way back in the old days it was common to grind cams so that the closure speed of the valve was slowed down by the cam.
They are called quietening ramps and were very common on motorcycles to make them mechanicaly quiet at idle
BSA used a grind like that from 1910 till 1966 on some models and on all their stationary motors till they sold that side to Villiers.
These cams had to be adjusted using the opposites method.

OTOH engine makers now tell us where is the first place they both of the cams are on their base circles ( maximum clearence ) and past anything like a quietning ramp or a decompression hump.
This is why B & S say to go 1/4" past tdc to avoid any chance of a bad adjstment due to the decompression ramp on the inlet.