Thursday, September 1, 2011

Rebuilding a Solex H 30/31 carb for the baja Part 2

Alright, on to part 2. Here we will build up the lower half of the carb and put everything together. Here is where we left off in part 1. The lower half is cleaned and ready. If you look down in the bowl in this picture, you will see where the drain plug goes in the side of the bowl. In the picture it's on the right hand side. The main jet will be installed down in the middle of the bowl with a screwdriver that will end up being placed in the drain hole. You will see in a few pictures what I mean.

 Remember I said to take lots of notes. Here are some of my notes on how the idle jet and main jet are installed. You can't take too many notes or pictures, even if you don't use them. Better safe than sorry.
 Here are the idle and power jets cleaned and ready to be installed. Don't mix these up when putting them in or your engine will run like crap. The idle jet goes in the hole that goes straight into the side of the carb and the power jet (the bigger numbered one) goes into the hole that goes into the carb diagonally.
 So in this picture the power jet is on the left side and the idle jet is on the right. You do not have to gorilla torque these in. In fact if you do your engine may not idle right.
Here is a picture looking down the float bowl drain. You can see I have installed the main jet in there already. This is the one I mentioned earlier in the post. Now I am running this carb on a 1600 dual port engine. Originally this carb came off a single port 1500. I wanted to run this carb because I had 2 choices. I have a 34 Pict 3 which is supposedly brand new. The guy I bought the motor from told me he could never get it to run right with this carb so I opted to go with the H30/31. This is a carb that has a very good reputation. I also have 2 009 distributors at my disposal and although the 009 is not my first choice, it is my cheapest option. I figured I would gamble with a 15 dollar rebuild kit on the carb over a 200 dollar distributor and a 34 Pict 3 that would probably still run like crap. Anyways back to why I am telling you this, because I am running this smaller carb on a bigger engine I read that you need to change the main jet to one that is at least 127.5 to 130. The main jet I had in it was a 120. Luckily I looked at the main jet in the 34 Pict 3 and it was a 127.5. Woo Hoo, so I put that one in and we will hope it runs good. I may need to go to the 130 because I am running a 009 but I will find that out when I get to tuning and driving it.
 OK Here is a picture looking at the left side of the carb. You can see the drain plug for the bowl with the main jet deep inside there, The upper large hole is the port for the bypass air screw, the small hole in the middle is the port for the CO adjusting screw and the lower large hole is where the bypass air cut-off valve goes. When you adjust your carb after your engine is warmed up, you will only be adjusting the CO adjusting screw and the bypass air screw.
 Everything is in except the bypass air cut off valve.
 I removed all the green gunk and installed this next.
The float will slide right down this slot and there is a small plastic piece that fits in above it.

 Make sure you put the plastic part in and make sure the curved part faces aft like this picture shows.
 Your rebuild kit will come with a few different bowl gaskets. It is VERY IMPORTANT to make sure you have the right one. Some look a lot alike so be sure you get it right. There may only be a small hole that is different but it's very important to have it right. Did I mention to make sure you get the right one!
 On goes the top now. Make sure the gasket is lined up and don't over torque it. This is a good time to make sure the inlet for the fuel line is in good and tight. There have been many VW engine fires started because the whole brass insert for the fuel line comes out of the top of the carb and fuel gets sprayed all over the hot engine. Some people even remove the fitting and tap threads into it and install a threaded fitting. Its a good idea. I just safety wire my fuel line clamp to a screw in the fuel bowl to make sure mine doesn't come out.
Here is the accelerator pump cover. It is a good idea to put a straight edge over it and make sure it is nice and even on all sides. If it's not get some sand paper and a granite block or other flat object and lightly sand it down. On my other bug, I rebuilt the carb and had fuel squirting out my accelerator pump every time I gave it some gas. I pulled it off and sanded down the cover and that fixed the problem. These tend to warp when they are over torqued.
 Put the spring in first on the carb side. Make sure the larger diameter is next to the carb.
 Install the accelerator pump diaphragm in the cover with the  metal post towards the cover. I don't think you can get this in backwards but you never know.
 Make sure everything is in nicely and install the screws. Use a light hand when tightening the screws. Install the rod and spring also with the correct bushing and safety clip on the throttle shaft.
I had to install an adapter plate on this carb because I am putting it on a dual port engine. The base of the carb is set up for a single port engine. The adapters are available at your local vw store or online and aren't very much money. To install it you need to remove the 2 studs from the base of the carb and then put the adapter on with 2 allen head screws. I used blue (medium strength) loctite on these screws. The adapter will only fit one way so it's a piece of cake to put on. Remember to install the gasket between the adapter and the carb.
 Back to the left side of the carb, I installed the return spring and the cut off valve. The cut off valve is powered by 12 volts and when you turn the car off it releases the plunger on the valve and cuts fuel to the engine. It helps prevent your engine from running on (dieseling). Don't worry if your valve looks like the plunger has been cut off. There are many of these that fail and they are fairly expensive, so instead of buying a new one, people cut them off and go on their way. In fact my other bugs plunger has been cut off and it runs just fine without it. As you can guess when they fail your car won't run. If you suspect yours has failed, just remove it from your car and hook 12 volts up to it and the plunger should retract in. If it doesn't buy a new one or cut the plunger off with a pair of side cutters, install it back in and be on your way.
 OK, everything is back together and I can't wait to give it a try. I just have to get some other things switched on the engine and install it in the bug and hopefully it will run like a champ.
 Here are the 2 engines. The upper one on the stand is the one going in. I have to exchange the exhaust, change the clutches out along with the front main seal of the engine. Inspect the gland nut, and maybe remove the intake manifold and clean out the pre-heat tube. The baja is going to be used throughout the winter so I want that working correctly. Stay tuned for more fun to come.
I have to shift gears and change the timing belt on my wife's Honda Odyssey tomorrow so I will blog about that next. I think I am on borrowed time with that one and if it were to break I would never live it down.


Anonymous said...

curious about an update! I have this carb and am considering whether or not to keep or get a 34-3

The Bug Boys said...

I have 2 bugs. 1 has the H30/31 carb I rebuilt here with an 009 Distributor. The other one has a 34pict3 with a SVDA distributor from I prefer the 34pict3with a SVDA distributor over the
H30/31 with the 009. Soooo, It depends on your distributor. If you are running an 009 keep the
H30/31. If you have a SVDA distributor, I would recommend the 34-3. The H30/31 ran ok with both distributors but a 34pict3 will not run for crap with a 009. Hope this helps.

Geoff said...

" I read that you need to change the main jet to one that is at least 127.5 to 130. The main jet I had in it was a 120. Luckily I looked at the main jet in the 34 Pict 3 and it was a 127.5. Woo Hoo, so I put that one in and we will hope it runs good. I may need to go to the 130 because I am running a 009 but I will find that out when I get to tuning and driving it. "

wondering what you ended up with. did the 127.5 worked for you or did you have to get the 130?

The Bug Boys said...

The 127.5 is working great. I am at 4200 feet here in Salt Lake City. Depending on your altitude it may be different but it is working great for me.

Unknown said...

Hey bro thanks for the tip on a bigger main jet! I have a Solex 30Pict3 running a 1976cc single port.It runs like a rape ape! Thanks from grimmkafer

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