Hello, I bought a main body and collection of parts for a Kingston L4 carb on an online auction site. I have all the parts I need to make this a complete carburetor (it will become my spare), but the main body has the remains of the original float needle seat stuck in it. The larger diameter top part that had the screwdriver slots is broken off, leaving the smaller diameter barrel part with the threads stuck (and I mean stuck!) in the main body.
Soaking with penetrating oil and using a screw extractor hasn't budged it. I have a cheap tabletop drill press, I may try drilling as much of the brass away as I can, maybe I can weaken the remains of the seat enough that it will let go of the cast iron without messing up the threads.
Another thought, since the seat is brass and the main body is cast iron, can I soak it in carb cleaner for a few days until the brass is dissolved away? Any other ideas?
As I said, this is a spare carb, so I have plenty of time to play with this and get it right.
Here are a couple of pics, first, of all the parts. I was impressed with the heft of the flapper valve, I expected it to be flimsy sheet metal, but it is a hefty brass casting.
Here's a closeup of the main body with the remains of the brass seat stuck in it. Notice also that one of the float pin bosses appears to have snapped off at some point and built back up with braze. This could torpedo my carb cleaner soak plan, since the cleaner would probably also eat this braze repair along with the remains of the brass seat.
If I decide I'm in over my head with this, is there someone I can send the main body to that could either repair it or take it as a core in trade (with a fee, of course) for a better main body?
Forget the screw extractor. That's gonna bust. Tap a flat blade screwdriver into the barrel (one with sharp edges) and try that first.
If youre gonna try to drill it, regrind the bit for brass or its gonna bust whichll make bad matters worse.
You can also invest in a set of left hand drills or, if youre feeling generous about getting yourself a nice birthday present, a "jewelers" torch for the acetylene outfit. Mine has an assortment of tips from a 0 to a 00000. Get in there and melt the brass out. Brass will melt wayyy before cast iron. Follow up cleaning with a bottom tap if you can find the correct size. You can also try to silver solder (!) an allen wrench in the barrel. Id put a tap in there first to have something shiny clean to solder to.
As a last resort, Id MIC the threads on a new seat and drill to the appropriate size, then "peel" the remains out. Don't worry about trying to true up the "barrel" portion as that will fall off after the drilling. Theres already a perfect centering hole in the jet. Make a bracket (fixture) from angle iron for the drill press and don't try it by hand. But what do I know... I was a lowly machinist at a power plant for 30 years...
Some more info...
Just some stuff to read... Become your own exspurt!
Great tips, thanks! I've had pretty good success on other jobs in the past with the "drill undersize and peel the remains out" approach, I think I'll try that next.
The pics were gone from the link you sent me, but I found others on another site. For the benefit of others, here's a stock drill bit, designed for cutting steel:
Here's the bit with the sharp edge ground flat so that it won't grab in brass:
I'll let you know how it goes.
LH drill bit after heating it cherry red and allowing it to cool completely. Or get a better carb to start with.
As Royce says, Heat it then quinch. Lots of times they will come out with your finger. KB
I think the thread is 3/8-24 and I believe a GM quadrajet needle and seat will fit.
Royce is correct about the heat and cool.
If it were mine,
I would put it in a bag and soak it with pentrant and put it in the freezer over night,then try again in the morning.
If you check about takeing the fuel bowels apart by doing a search here it will help you understand what I am saying better.
The brass shrinks in the cold much more than the cast.
This loosens it and lets the oil in.
Success! The drill and peel method worked fine, no need for heat or cold. I cleaned up all the threads in the casting, now I just need to clean up the casting itself to get it ready for paint.