vw motor for bug

[hopken92]

hi i have a 1978 conv bug champagane edt.? iwas just wondering about the motor is it the same 1600 fi or carbed and do they interchange thanks ken

[david58]

Welcome to the STF hopken92 I think we need to move your thread over to the newbie forum. There are some differences in the blocks, heads and intakes, but still are somewhat interchangeable I believe. Need a little help here doc I can't find my thread moving magic wand.

[hopken92]

i have complete fi motor and have chance to buy carbed motor any info would be great thanks

[david58]

i have complete fi motor and have chance to buy carbed motor any info would be great thanks

Are you wanting to put the carbed engine in with carbs or convert it to fuel injection?

[hopken92]

i want to put my fi system on a carbed motor, iam trying to put on pic it wont let me

[Bugfuel]

FI heads have a threaded boss for a temperature sensor, that is not there on a carbed head.
You would need to work around it or swap heads. I'm not sure the valve sizes are the same either. The crank, block, pistons and cylinders are all the same. I'm pretty sure.

[hopken92]

would the valve size diff still let it run normal looking for every day driver

[Marc]

FI Bug engines have the same size valves as the `66 1300cc singleport, 33x30. Carb'd 15/1600 engines and FI Type III use 35.5x32. I don't think there'd be any problem running the larger valves with the L-Jetronic FI, but as Jan pointed out you'd need to come up with a place to install the (vital for operation) cylinderhead temp sensor....without welding something on, the only place that comes to mind is in the casting web below #4 exhaust port - you might be able to drill/tap a hole there that could hold the sensor.
Besides the smaller valves, Bug FI motors also used larger exhaust valve stems (9mm vs 8mm) and their cases were cast from an alloy (AS21) which retains greater strength when hot. Both changes were made to support the hotter running resulting from leaner "emissions" calibration of the FI and hotter thermostat. I'm sure that many engines have been rebuilt using AS41 cases and/or Type III heads which worked OK, they just aren't the parts that the VW engineers considered necessary with L-Jet.
You'll basically need to strip the new engine down to longblock to transfer over all of the intake/exhaust bits and sheetmetal; some studs will need to be replaced with longer ones.
Personally I'd leave the engine carbureted and graft it into the car...not too complicated, just requires extensions to the overcylinder tin and some other minor sheetmetal tweaks, a different throttle cable and modification to the heaterbox linkage. The electric fuel pump must be disabled/bypassed and power withheld from the FI system. You'll have a mess of unused wiring to tether out of the way in the engine compartment, but that's preferable to removing the FI harness if you expect you (or the next owner) might ever go back to stock with a correct engine.

[crvc]

Years ago I had a 1971 Porsche 914 which came with a VW D-jetronic FI type-4 motor. I tried to keep it stock but it became increasingly difficult to keep it running as the electronic parts began to fail. My dad is an electronics expert--he taught electronics in the military-- and has owned bugs continuously for 50 years. He also had two 914s and couldn't keep the stock FI working. For me the end was the third time I found gas filling the crankcase. I stripped out the FI, went to a Weber carb and had better performance. The only trade-off was losing a few MPG.

kevin

[hopken92]

i think i will put the carbs in and tape off all the fi wires if any one has done this any tips would be great

[Marc]

Done it lots of times. My daily driver is a `77 with a `70 1600SP carb'ed engine.
You can run either the FI-style exhaust system or the carb'ed style (the FI version has no provision for intake manifold preheat so it's not a good choice for a single-carb setup, but that's no problem with duals). Which you choose determines what rear tin will be needed since the freshair hose holes are located differently. The linkage on carb'ed heater boxes needs minor alteration for the cables to hook up, while the FI muffler requires one longer stud at each rear exhaust port.
The whole FI wiring harness is independent of the main wiring, so almost no alterations are needed there. I've never been concerned with ease of reversibility so I've just removed the FI harness, series resistors, ECU, etc. completely and plugged the big hole in the firewall but for the sake of the future value of your convertible you might not want to get that radical. If you use a generator or externally-regulated alternator there are some minor modifications needed to accomodate the voltage regulator, and if you use the FI fan shroud the throttle cable guide tube needs to be relocated. There'll be no use for the fuel return line on the RH side of the tunnel, so it can be capped off at both ends (and at the tank), and the fuel supply line on the LH side needs to be stepped down to fit the smaller carb'ed fuel pump feed pipe. If you don't use the FI overcylinder tin there'll be a gap at each side of the engine compartment, simple enough to fabricate some extension panels to close that off. With some dual-carb linkage it's not even necessary to change the throttle cable, although you may need a longer one...for a single carb. a `74 cable is just right.