So I have heard for my Briggs 70's era model 80204 0430 3hp 4 stroke engine, that the piston position should be 1/4 inch down from top dead center to set the gap (valve / tappet clearance). That was from the lawn mower shop guy.
I saw that said the same on the Briggs site:
http://www.briggsandstratton.com/eu/en/support/faqs/servicing-the-valves
I 1st however had seen this pdf:
http://www.oldengine.org/members/murphy/Briggs & Stratton Repairman's Handbook.pdf
In the pdf I did not see on page the same info. It said as in the jpeg I copied on page 41 where it says to have piston at highest point (think TDC), then rotate flywheel 180 degrees. That is how I did it.
I only changed the intake for adjustment as before it was no gap. I set at 0.007 inch in the range OK for the table 5digit A or B 0.005" to 0.007" intake valve clearance.
Since it runs but won't idle now, I'm thinking totally separate problem. Cleaning or replacing the carb, fuel-line, filter is what I am to do. It was actually intermittent idle, and when it would not idle it cut out. At above throttle it never cut out and kept running.
Just for thought, where it is the setting if that 1/4"difference piston being moved down from TDC, would my measurement for gap be off?
I think since the 1/4"down would have the lobe of the intake cam already pushing sooner on the tappet so the gap would have been less to start with. Effectively I think that means that (strike this out) ---> I could have taken off more of <--- (strike this out)the bottom of the valve stem to get the measurement right for the gap. (I actually took too much according to new method (If And Only If It Applies, IFF to my model engine), where otherwise on website 1/4 inch ATDC (AFTER Top Dead Center)
So, I think if after seeing about fixing the idle issue the way I am intending not messing with the intake valve timing again, only if it does not work, I could just take a little bit more off of the bottom of the valve stem.
In any case, prior to the intake valve being adjusted it was no gap and gas was spraying for 1/3rd of the compression stroke out the throat of the carb at the air-filter and wetting it. After a while it was choking the air flow and wasting air-filter way too prematurely. Now with a intake gap at 0.007", the way I measured as in the pdf, I can even take a whiff of the air-filter and not even smell gas on it after a few minute of test time at high revs.
Any reason of the difference for where the piston should be located with respect to TDC in the different methods greatly appreciated.
Thanks
MT
PS, I think maybe the pdf is telling for 5 digit models but, I was thinking 80202 was 5 digit. Maybe error as it really might be all 80202 0430.
Based on the last pic image of the cover of book in jpeg by Briggs it does say cost being $1 for the manual. I think it is for older engines like my 5S and 6S, but not the 80202 0430 and so the newer method for setting valve clearance probably is from the website. I was unsure as they call 80202 0430 not a current model. They say you have to use archives or maybe it is not on the website, I found the copies from Old Engines website. It is from the 70's is what I a pretty sure of.
I'll see if the new carb only 18 bucks and a new filter and line, along with gas tank cleaning do for the idle problem. I'll also inspect the old carb and have carb cleaner to clean and keep the old carb as a spare.
--------------------- correction--------------- see same as above:
I think since the 1/4"down would have the lobe of the intake cam already pushing sooner on the tappet so the gap would have been less to start with. Effectively I think that means that (strike this out) ---> I could have taken off more of <--- (strike this out)the bottom of the valve stem to get the measurement right for the gap. (I actually took too much according to new method (If And Only If It Applies, IFF to my model engine), where otherwise on website 1/4 inch ATDC (AFTER Top Dead Center)
I saw that said the same on the Briggs site:
http://www.briggsandstratton.com/eu/en/support/faqs/servicing-the-valves
I 1st however had seen this pdf:
http://www.oldengine.org/members/murphy/Briggs & Stratton Repairman's Handbook.pdf
In the pdf I did not see on page the same info. It said as in the jpeg I copied on page 41 where it says to have piston at highest point (think TDC), then rotate flywheel 180 degrees. That is how I did it.
I only changed the intake for adjustment as before it was no gap. I set at 0.007 inch in the range OK for the table 5digit A or B 0.005" to 0.007" intake valve clearance.
Since it runs but won't idle now, I'm thinking totally separate problem. Cleaning or replacing the carb, fuel-line, filter is what I am to do. It was actually intermittent idle, and when it would not idle it cut out. At above throttle it never cut out and kept running.
Just for thought, where it is the setting if that 1/4"difference piston being moved down from TDC, would my measurement for gap be off?
I think since the 1/4"down would have the lobe of the intake cam already pushing sooner on the tappet so the gap would have been less to start with. Effectively I think that means that (strike this out) ---> I could have taken off more of <--- (strike this out)the bottom of the valve stem to get the measurement right for the gap. (I actually took too much according to new method (If And Only If It Applies, IFF to my model engine), where otherwise on website 1/4 inch ATDC (AFTER Top Dead Center)
So, I think if after seeing about fixing the idle issue the way I am intending not messing with the intake valve timing again, only if it does not work, I could just take a little bit more off of the bottom of the valve stem.
In any case, prior to the intake valve being adjusted it was no gap and gas was spraying for 1/3rd of the compression stroke out the throat of the carb at the air-filter and wetting it. After a while it was choking the air flow and wasting air-filter way too prematurely. Now with a intake gap at 0.007", the way I measured as in the pdf, I can even take a whiff of the air-filter and not even smell gas on it after a few minute of test time at high revs.
Any reason of the difference for where the piston should be located with respect to TDC in the different methods greatly appreciated.
Thanks
MT
PS, I think maybe the pdf is telling for 5 digit models but, I was thinking 80202 was 5 digit. Maybe error as it really might be all 80202 0430.
Based on the last pic image of the cover of book in jpeg by Briggs it does say cost being $1 for the manual. I think it is for older engines like my 5S and 6S, but not the 80202 0430 and so the newer method for setting valve clearance probably is from the website. I was unsure as they call 80202 0430 not a current model. They say you have to use archives or maybe it is not on the website, I found the copies from Old Engines website. It is from the 70's is what I a pretty sure of.
I'll see if the new carb only 18 bucks and a new filter and line, along with gas tank cleaning do for the idle problem. I'll also inspect the old carb and have carb cleaner to clean and keep the old carb as a spare.
--------------------- correction--------------- see same as above:
I think since the 1/4"down would have the lobe of the intake cam already pushing sooner on the tappet so the gap would have been less to start with. Effectively I think that means that (strike this out) ---> I could have taken off more of <--- (strike this out)the bottom of the valve stem to get the measurement right for the gap. (I actually took too much according to new method (If And Only If It Applies, IFF to my model engine), where otherwise on website 1/4 inch ATDC (AFTER Top Dead Center)
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