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steve(ill) 
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Joined: 11 Sep 2009
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 Topic: Briggs 18 HP opposed twin
Posted: 25 Sep 2024 at 1:34pm |
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Taking an old engine apart.. Intake valves have a seal/ plate that the spring sets on.. Both exhast springs were setting on the aluminum housing.. No steel plate / washer below the spring... Is that normal ?
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Like them all, but love the "B"s.
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steve(ill)
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Location: illinois
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Posted: 25 Sep 2024 at 4:44pm |
No close ups of 18 HP on You Tube... but i did see a 6.5 HP that does NOT have the backup plate.. Guess i am not use to seeing that.. Have done very few small motors and its been 15 years since the last one...
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Like them all, but love the "B"s.
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Walker
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Joined: 12 Sep 2009
Location: oh
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Posted: 25 Sep 2024 at 5:10pm |
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Always leave flathead valves for last. That way after doing the entire engine you'll feel obligated to finish the damn job.
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Herb(GA)
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Joined: 15 Sep 2009
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Posted: 28 Sep 2024 at 7:20am |
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Walker, I enjoyed your reply. Herb(GA)
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acken
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Posted: 28 Sep 2024 at 7:59pm |
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I find it hard to believe they would let steel spring run directly on aluminum. Have you checked if it show up in parts book/diagram?
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steve(ill)
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Posted: 28 Sep 2024 at 8:49pm |
looking at You Tube videos and this engine is 20 years old.... None seem to have a plate under the spring on the FLAT HEAD engines.. There is NO valve guide so nothing to center the washer / plate.. Guide is just a drilled hole thru the aluminum housing. Spring just sets on the aluminum case...
Engine ran low on oil and one rod stuck to crank and broke.. No other damage. I polished the crank and looks good. Bought a "kit" on e-bay with pistons , rings , rods, wrist pin, valves, seals and gaskets for $300. Almost back together today... I could probably get by with a rod , gaskets and seals... but thought for the old girl i would go ahead and get new pistons / rings / heavy rods and new valves.. Took very little to lap the valves, but had to grind about 25 thousands off the stem of each to get the valve clearance... typical..
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Like them all, but love the "B"s.
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HudCo
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Joined: 29 Jan 2013
Location: Plymouth Utah
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Posted: 29 Sep 2024 at 10:02pm |
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25 seams like alot might be better off with some new valves that dont sit so deep in the seats
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steve(ill)
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Posted: 30 Sep 2024 at 12:42pm |
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HUD... i miss spoke.. I got NEW valves in the kit.. Old seats were in good shape.. There are no "valve adjusters" on the L head engine.. You grind the end of the stems to get the proper clearance you want. The valves come EXTRA LONG so you can grind to fit.. Once i got 8 thou on the intakes and 12 thou on the exhaust, i lapped the new valves to the old seat.. I dont think i spent 1 minute on each valve to get a nice seat.
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Like them all, but love the "B"s.
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HudCo
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Posted: 30 Sep 2024 at 10:27pm |
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i missed the new valve part
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DaveKamp
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Posted: 01 Oct 2024 at 9:21am |
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It's been almost 40yrs since I worked on one of those, but I recall a plate under those springs. IIRC it had something to do with how the valve was to rotate... I THINK that without it, the intake valve wouldn't rotate right... exhaust didn't have any problems with it, just the intakes...
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Ten Amendments, Ten Commandments, and one Golden Rule solve most every problem. Citrus hand-cleaner with Pumice does the rest.
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steve(ill)
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Posted: 01 Oct 2024 at 8:30pm |
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Intake just has a top spring cover with elongated hole in it.. SNAPS on over the valve stem.. Exhaust valve has a rotater on top with standard KEEPERS in it to retain the valve.. No bottoms on the springs. They set right on the aluminum housing.. there is no valve guide protrusion to hold any plate in place.
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Like them all, but love the "B"s.
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