Have no idea what you mean by releases, what releases? TDC cannot be arbitrary, it is an exact point. Have no idea what you mean by ( back up, feel resistance, spot on ). This is how I check valve clearances. Remove spark plugs, while rotating engine by hand watch valves until both valves are closed. Insert a small screwdriver into spark plug hole and while rotating flywheel back and forth you will feel piston moving up and down. Find TDC and then rotate flywheel forward until piston moves about 1/4” down. Now check your clearances. If clearances are off, adjust then rotate flywheel through 4 complete cycles. Now repeat the steps to find 1/4” past TDC and recheck clearances. If off repeat procedure until you have clearances within specs. Others have different procedures, but this is the procedure I use when I check and adjust valve clearances. Remember we are not stand there watching what you do, please paint us a better picture.
Push mower oil leak Briggs
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Rivets;
He's got a "Flat head", non OHV engine (3.5HP Briggs). Your talking about adjusting an OHV engine.
Oranges to apples...
I forgot if the access to the valves and tappets are inside the side "breather" (I think they are-been awhile((45 years)).
If so, get the cam and tappets loose/away from the valve so the cam lobe is NOT pressing upward.
I'd measure the widest gap, should get you in the ball park. Likely still within spec's'...
He's got a "Flat head", non OHV engine (3.5HP Briggs). Your talking about adjusting an OHV engine.
Oranges to apples...
I forgot if the access to the valves and tappets are inside the side "breather" (I think they are-been awhile((45 years)).
If so, get the cam and tappets loose/away from the valve so the cam lobe is NOT pressing upward.
I'd measure the widest gap, should get you in the ball park. Likely still within spec's'...
Rivets;
He's got a "Flat head", non OHV engine (3.5HP Briggs). Your talking about adjusting an OHV engine.
Oranges to apples...
I forgot if the access to the valves and tappets are inside the side "breather" (I think they are-been awhile((45 years)).
If so, get the cam and tappets loose/away from the valve so the cam lobe is NOT pressing upward.
I'd measure the widest gap, should get you in the ball park. Likely still within spec's'...
Ok. Yea. I have the head off doing a rebuild. I’ll check cam lobes. ?
The procedure is the same on a flat head or OHV. Both have tappets, cam lobes, compression release. The L-head is just more time consuming, because to do it right you should have the springs on when measuring and if the clearance is not correct, you are either grinding the stem or seat, not adjusting a nut. If you grind the seat you should relap the valve. Most want to cut corners by not installing springs or relapping after grinding seats. If you have the head off you should still rotate a 1/4” past TDC to make sure the compression release is off. Only oranges to apples if you feel you need to take shortcuts. Shortcuts in our shop normally come back to haunt you, so we use a procedure which we can warranty and not pray that the short cut will work.
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"Apples to oranges" was referring to an OHV engine vs an "L" style engine, NOT a short cut. As noted, there are no screws to adjust clearances.
Also as noted, springs should be installed. It's too easy to push a feeler gauge in-between with no real tension between the valve and the rest of the valve train.
Needless to say, the side cover should be installed, just snugged down, to keep the cam from flopping downward (screwing up actual clearances).
To my knowledge, (please advise), the old, 3.5 HP B&S engines didn't have compression releases, didn't need them.
Also as noted, springs should be installed. It's too easy to push a feeler gauge in-between with no real tension between the valve and the rest of the valve train.
Needless to say, the side cover should be installed, just snugged down, to keep the cam from flopping downward (screwing up actual clearances).
To my knowledge, (please advise), the old, 3.5 HP B&S engines didn't have compression releases, didn't need them.
Got it. That answers my question. Yes. I agree the tension with springs on makes total sense.
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Do you know for certain (just curious), if the old B&S engines had compression releases built in?
I know my 7HP Briggs OHV Snapper valve adjustment is 1/4" past TDC compression stroke (adjusted a couple of years ago) however didn't know why the 1/4".. That makes sense, tks..
Lastly, for the larger engines (with compression releases), are most valves adjusted also at 1/4" beyond TDC?
I know my 7HP Briggs OHV Snapper valve adjustment is 1/4" past TDC compression stroke (adjusted a couple of years ago) however didn't know why the 1/4".. That makes sense, tks..
Lastly, for the larger engines (with compression releases), are most valves adjusted also at 1/4" beyond TDC?
Unless you know for sure that there is NO compression release, (have sump cover off and visually check) set the clearance 1/4” past TDC. As I would tell my students, “Why take a chance” takes no extra time to always follow the same procedure no matter which engine you have. In a shop if everyone is using the same procedure, no one is guessing if it was done right and we can feel confident, as we warranty all repairs. What someone does in their garage is totally up to them, they play by their own rules.
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Thanks and good information.
I just had to adjust two exhaust valves on my Yamaha, 600cc, 4 cylinder, 4 valves /cylinder OHV engine. Both were .001" too tight. A bit more involved than a mower engine..
Per the manual, all adjustments are made at TDC for each cylinder. (which I did).
Per a forum I frequent, (very knowledgeable folks), as long as the lobes are 180 degrees from the bucket(shim and bucket design), you can measure... The cam lobe circumference would be the same until you hit the ramp lobe. This bike does not have a compression release...
I can see larger single mowers (or any large single/two cylinder engine) needing the release..
I just had to adjust two exhaust valves on my Yamaha, 600cc, 4 cylinder, 4 valves /cylinder OHV engine. Both were .001" too tight. A bit more involved than a mower engine..
Per the manual, all adjustments are made at TDC for each cylinder. (which I did).
Per a forum I frequent, (very knowledgeable folks), as long as the lobes are 180 degrees from the bucket(shim and bucket design), you can measure... The cam lobe circumference would be the same until you hit the ramp lobe. This bike does not have a compression release...
I can see larger single mowers (or any large single/two cylinder engine) needing the release..
Thanks and good information.
I just had to adjust two exhaust valves on my Yamaha, 600cc, 4 cylinder, 4 valves /cylinder OHV engine. Both were .001" too tight. A bit more involved than a mower engine..
Per the manual, all adjustments are made at TDC for each cylinder. (which I did).
Per a forum I frequent, (very knowledgeable folks), as long as the lobes are 180 degrees from the bucket(shim and bucket design), you can measure... The cam lobe circumference would be the same until you hit the ramp lobe. This bike does not have a compression release...
I can see larger single mowers (or any large single/two cylinder engine) needing the release..
Ok so clearance is way too large. Exhaust .031 and intake .045! Will refacing the valves get me close enough to workable numbers?