B&S 42A707 valve seat damage

I have a Briggs 18.5 hp model 42A707 with a valve seat that came loose and lodged under the valve. There is some gouging next the the valve port. The other cylinder appears ok. I need to know if this is a scrap engine or can a person fix this issue with reasonable cost and effort, What is the proceedure?

 

With that damage under the valve from it running so much with the seat loose, repair is uncertain. Put the seat back in place and see if it will fit snugly. If so, take a center punch and peen the aluminum around the seat over and over to lock it in place. This is the briggs procedure for repairing the seat and I have done it many times with success but that one has considerable damage. Worth a shot though, it doesn't take long to do. It's the intake valve, so I think it will probably take the repair well enough to get it back in service even if it is a little leaky.

 

I'll be dang. I did as you said. I had to use a screwdriver to pry the valve out enough to move the seat. I jockeyed it into place an tapped it a couple of times with a hammer and screw driver to center it properly. Then I use the handle end of a screw driver and tapped the valve to seat the seat. I then used a punch to peen around the valve seat. I'm amazed! It started right up.

Now I have what I assume are carb issues. The engine is on a simplicity lawn tractor. When it is running it idles fine...with the choke pulled out. Push the choke in and it stalls. With the choke out I can rev it up and then push the choke in slowly but it soon stalls. Does this sound like typical dirty carb to you?

 

Yes, dirty carb. There is a drain plug on the side of the carb bowl, take it out and the jet is through that hole. You can use a high pressure air gun with a small nozzle that fits in there and blow it out and/or torch tip cleaners to clean out that jet and reassemble.

 

I did what you recommended but I still have carb issues. I took it apart and the gasket between the two body halves what stuck all around and was pretty much destroyed separating the body halves. I ordered a new gasket today.

When I opened the carb the float bowl was dry as a bone. Is it possible for and engine to run without gas being in the bowl? Maybe it just evaporated, but I have never opened a carb and found it totally dry inside. Just wondering. There was dried residue caking the inside of the bowl. That should have held a little moisture also.

Anyway, part will be here in a week. Thanks for your help.

 

It has to be getting fuel from somewhere. Check the crankcase, it may be full of gas.

 

So I cleaned out my carb. Put in a new main body gasket. Made it run a little better. It will rev better and idle better. But with no choke it dies. With full choke it runs but smokes. With mid choke it dies. Engine also "hunts" very moldly, a slight increase and decrease in rpms. Doesn't seem to matter if I leave the air cleaner out or put it in. Does this sound like starving for gas? I will now check fuel supply the take carb off again and reclean it...after I go buy a new can if carb spray.
Heres a bad thing...The casting inside the carb that contains the threads for the main jet is cracked. The jet still screws in snuggly and I think the crack does not extend past the threads. I don't know if I did this or if it was previously cracked. Would it be possible the seal the crack with JBWeld? Is this likely whats causing the problem or likely not?

 

sounds like it still has a fuel issue jb weld does not really hold up long term in fuel might look for another carb.

 

Agreed, I would source another carb. I think the knockoff carbs are cheap on ebay and amazon.