Fuel injection to carb

[Josh8324]

Hi guys- I have a 75 super that I want to convert to carb. Any help with wiring and any/everything I’ll need to know. Thanks!

[Lost69Convertible]

Hi Josh. Welcome to TheSamba.

I’d like to ask about your reasons for converting from FI to carb?
If you want a stock engine that runs well, there are FI experts here that can help you repair and maintain what you have now.
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1956 Beetle Ragtop: My Father's car
1969 Beetle Convertible: My first car. I loved it, I lost it, and I never got over it.
1979 Super Beetle Convertible

[virusdoc]

[Josh8324]

I bought a kit from jbugs for a single carb. All of the components should be included but my concern is the wiring. I have a long background in auto body and have put many cars together over the years but my background is more on the lines of a small block Chevy. This is my first vw and the car is for my wife. In my head I’m thinking that this thing should be primitive and should only need a few wires to run it but figured I’d ask you all here first. Would I be able to put in a earlier harness to the motor?

[busdaddy]

I think you are making a huge mistake, but everyone has to learn the hard way. Don't butcher anything, or throw stuff out, you'll be looking for it later.

[virusdoc]

Busdaddy's cryptic reply is due to the fact that the Chinese 34PICT-3 clones sold with these kits are notorious for being low quality, and for the ones that can be made to work, significant cleaning, adjustment, and rejetting is often necessary to get there.

Most people who want a reliable center-mount carb experience purchase a rebuilt German carb from Tim at volkzbitz.com. I have done this, and I am quite happy with it. You'll also want a decent distributor, and for that there are a handful of vendors on the site that do good work refurbing German or Brazilian distributors. I personally have used Bill Fowler, the owner of Sparxwerks.com. You'll want an SVDA distributor like the 034. There are certainly clones available, but of varying quality.

This is all based on assuming you purchased this kit:

https://www.jbugs.com/product/111-CARB-KIT.html

From a wiring perspective, all that requires is 12V+ for the choke and throttle shutoff solenoid. Both can easily be jumpered off the + terminal of your existing coil.
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1976 Convertible Super Beetle, "June Bug".
Self-rebuilt 1904
1976 Campmobile 2.0L FI, "Kermit"

[virusdoc]

Oh, and do not under any circumstances try to skip installing the heat risers properly. If your exhaust is not drilled for them, your vehicle will run like absolute shit.
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1976 Convertible Super Beetle, "June Bug".
Self-rebuilt 1904
1976 Campmobile 2.0L FI, "Kermit"

[busdaddy]

[APPLEGREENVW]

A 4 into 1 header with the pre-heat tube, is the best exhaust setup for the FI to center carb conversions.
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Parts for sale https://www.thesamba.com/vw/classifieds/search.php?username=APPLEGREENVW

02/76 Beetle sedan

[APPLEGREENVW]

Someone needs to start a how to, FI to carb conversion sticky.
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Parts for sale https://www.thesamba.com/vw/classifieds/search.php?username=APPLEGREENVW

02/76 Beetle sedan

[plotch]

I have a 75 converted to carbs. the fuel injection harness has a jumper wire in it. I can get you the terminal numbers/wire colors if you wish.

[Rome]

For a stock-style 34 PICT-3 carburetor, you'll need only 1 wire approx. 12" long with 3 spade connectors. It comes off the "+" terminal on the coil, which should have the number 15 molded into the top. 15 is German industry standard for "ignition switched on". One spade goes to the idle cut-off valve on the left side of the carb. The longer length of wire is attached to/crimped into that middle spade connector and continues to the automatic choke on the upper right side of the carb. Wire can be approx. 18 ga.

All other wires for the original engine's fuel injection system should be looped together, tie-wrapped and pushed frontwards so that they are out of the way of the engine.

The responses for the intake manifold pre-heat are valid. The center mounted stock carb needs the pre-heat to prevent condensation forming on the outside of the manifold pipe under the carb. The 2 legs of the pre-heat attach to each side of a stock muffler or an aftermarket header, just like in APPLEGREEN's photo where you can see those small horizontal flanges. Problem is that the original muffler for fuel injected Beetles does not have those flanges because there was no need for warming up the manifold using engine heat.

If you want to use a stock-style muffler for your carbed engine, the muffler tips will contact the underside of the rear apron, because when such a muffler was used on a carbed engined Beetle (thru '74 model year), those Beetles had the 2 upward cutouts in the rear apron for the 2 muffler tips. So this is another reason for using a header, since the muffler portion lies below the apron and there is no interference/contact with the apron.

Your fuel injected engine utilized a high-pressure electric fuel pump up near the fuel tank. The engine case did not have the 2 mounting studs nor even the hole in the top of the case for the carbed engine's mechanical fuel pump and its Bakelite pedestal. So the usual method of providing the needed low fuel pressure that a carb needs is to buy an electric pump that has approx. 2.5 to 3 psi output, and mount it up front near the tank. The pump is usually activated by a single wire that gets current once the ignition switch is turned on. You mount the pump on a rubber isolated base/stud because its internal pulsations are transmitted thru the pump housing and the car body if not isolated.

Your fuel-injected fuel tank has a small nipple somewhere for the fuel injected excess fuel return circuit. That circuit is no longer used for a carbed engine so that the nipple should have its feed hose removed and a simple plug installed on the nipple.

[Rome]

My '77 Beetle was also originally fuel injected. The PO removed all the FI components but kept the original harness in the engine compartment. He installed dual carburetors onto the FI engine case and had a header similar to the one in APPLEGREEN's shot. I kept some type of dual carb setup on another carb-based engine for many years. 2 years ago I removed the dual carbs and went for a stock single carb setup temporarily. This is how the parts look mocked up out of the car. The air cleaner is an oil-bath unit from a '71, though earlier and later air cleaners will also fit onto the carb. Carb is a German-built Solex 34 PICT-3. Intake manifold is also original German with the small preheat pipes cleared out from the usual carbon buildup inside so that heat/air can actually freely pass thru. Painted with POR-15 high-heat grey manifold paint.

Here's the engine. You can see it does not have the mechanical fuel pump, though this particular engine was a carb-based engine so that it has the 2 mounting studs. I have a simple block-off plate over the fuel pump hole because there's a low-pressure electric pump up front that is mounted to the same rubber isolated base as the original FI high-pressure pump.

[EVfun]

I don't see a fuel pump control relay in that kit. Something like the KAE 3.300.400, that connects to both sides of the ignition coil and ground so it can shut the relay off if the engine quits running (like after an accident.) The other 2 contacts go to power and the fuel pump.

Already mentioned is that I see no way to connect a heat riser with the kit as the FI engine does not have the heat riser ports to connect to the heat riser pipes on the intake manifold. You would also be well served to get a stock air filter with a preheat connection to supply warm air to the carb in cool weather. The Bug engine is real good at icing up the carb.

Personally, I like the stock L-jetronic fuel injection. It is sensitive to bad plug connections, but that is easy to fix. You may have to repair or replace the air flow meter, or install new injectors too. Once fixed up it runs very smooth, better than any carb equipped Bug engine I've owned. If you have to pass a smog test it may be mandatory to keep the stock set up.
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