How to fix a valve on opposed twin Briggs and Stratton engine without replacing it.
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- เผยแพร่เมื่อ 12 ม.ค. 2025
- I ground too much off the valve stem of the intake valve in my 18hp Briggs & Stratton opposed twin flathead engine. How to fix it without replacing the valve.
Nice work salvaging the valve George. That should last a long time.
I sure hope so Lloyd. Thanks for stopping by
That was a very helpful video. Now I'll go back and find the one before it.
Thanks Richard
I like the way you never give up, Sorry I can't help with the carb blowing exhaust.
Thank you Steve
I don't know if you have done a leak down test and a compression test. I would also think that the valves need to be lapped. However you did make a valve longer!!!! 🙂
I have lapped both intake valves, including the one that I extended...because of my hasted in grinding it the first time around. I am befuddled at this point, but have ordered another set of head gaskets in preparation for diving in again. I will do a compression test next and if it seems necessary, I will do a leak down test too. Thanks for the suggestions Bruce. I appreciate it very much.
I need this video. I've got to grind the valves on Dad's old John Deere I think so I need to know how to do it.
You can do it! I didn't show the lapping process, but I'm sure you remember how to do that, eh? Thanks for stopping by.
Got to be blowing back up the intake valve... Lapping should help with that like others suggested.
I did lap 2 of the valves that were suspect, including the one that I had to regrind, to no avail. I have ordered another set of head gaskets. I had wondered about valve timing, but the camshaft hasn't been removed, which is impossible to do anyway without pulling the crankshaft to remove the ball bearing. It starts really well. We'll keep double checking things. What makes me wonder is why it is on both sides? I have lapped both intake valves. Thanks for the great suggestions.
Camshafts on these briggs have a built in compression release on their intake lobes. This will allow these engines to start easier. The lobes are easily to remove by the proper tools. If you remove these excess bumps on the intake lobes you won't have the blow-back your seeing out the carbs. Second option is to buy a aftermarket Camshaft from someone like ARC Racing. Hope this helps my man..
! Good luck with it.
But why wasn't it blowing back with the single carburetor on it? I really don't want to pull the whole engine apart at this point, which is what I would have to do to replace the camshaft, since the crank gear is a press on unit. Thanks for the suggestion. I appreciate it.
I don't know why that exhaust it coming out of the carb like that,,, if you did many b&s valves it would be handy to get one of those little valve compressors , they make it so much easier.
I don't do them too much anymore, but after fighting with my homemade one I am seriously considering buying a proper valve spring compressor. Thanks Vernon
George, Just thinking, how are the rings on it. Did you replace them?
I haven't replaced the rings and really hope I don't have to do a complete teardown at this point. This was supposed to just be a cleanup and paint... Thanks Steve
Nice work on the valve George. I am just as frustrated as you are about the exhaust coming back through the carbs. As mentioned in another comment after you set the valve clearance did you lap the valves I wonder if that could be the problem?
I did lap the valves that were re-adjusted, and rechecked them with the valve springs installed. I didn't see any indication of burning valves except on the intake valve on the passengers side (?!). That one had some pitting on the valve itself but looked great after lapping it in. I do have another intake valve, "just in case". Thanks Bob
George, did you lap the valves in with lapping compound and check the .007 with the spring installed.
I was just about to ask the same thing ...
I lapped only two of them, as the others were in very good condition and sealing all the way around. Strangely, I didn't notice this back pressure through the carburetor when it was just running with one carburetor... I did also recheck the valve clearances after the springs were re-installed, though I didn't show it. I have ordered another set of head gaskets, just in case I need to tear it down again and recheck. It seems strange that it is on both sides... Thanks for stopping by Junior.
I did recheck the valve settings with the springs re-installed and I only lapped 2 of the valves as the others looked very good and showed no signs of leakage.
Question could this engine possibly have a decompression cam holding the valve open?
Hopefully George can get the stuff going up through the carburetors what’s George think it might be me I don’t know much about carburetors
It doesn't actually have anything to do with the carburetors themselves, most likely a timing issue or some other problem with the valves. Thanks Mason
Cool
Thanks Terry
Great lessons on the valve work George. I read the comments and Nobody mentioned the Timing.It seems too advanced judging by the blow-back.Can you turn your flywheel reverse a hair while the crank stays forward?The Woodruff key can be shaved and it allows you to advance or retard timing that way. Best wish for it being an easy fix.
I was wondering about timing advance too, Bry. The change the crank-camshaft timing I would have to tear down the whole engine since the camshaft gear is blocked by the crankshaft bearing, which is press fit. I'm still pondering on it. What has me stumped is that there wasn't any back pressure when it was just the single carb...Thanks for the great suggestions. I appreciate it.
I don't think it's related but the spark plugs were jiggling around like they were loose.
Yeah one of them was loose, but you are right, it wouldn't affect this problem. Thanks Terry
What engine model did you get the valve covers from? They look pretty darn close to the ones for a 320000.
Valve covers? You mean where the breathers are attached or are you referring to the finned flat heads? The breather/valve covers are original to this engine and I don't have all the information on it since the ID tag was worn off. I am guessing that it is the 18hp version of this venerable old opposed twin. Thanks
@@TheShadeTreeFixitMan someone mustve added those before, those are not original to a opposed twin. I really like them and I want to find what they are so I can put them on my builds.
Boy, that’s a stumper George.
A stumper or a stomper? Hmmm... thanks Matt.
Your valves are floating! You need better valve springs!
Floating at idle? Why didn't it do it with a single carburetor? Thanks for the suggestion.
It look like it was only doing it at higher RPM's?@@TheShadeTreeFixitMan
A single carb has a intake that feeds both CLY so it might be blowing exhaust/fuel from one CLY to the other with out noticing it? @@TheShadeTreeFixitMan