74 412 wagon question Fuel injection vs. carbs

[Big Mike Cbad]

Hello Samba experts, could use some help. Just bought a 74 412 wagon project in California. I knew it did not have the original engine in the car. Another engine was installed, but was not complete and not running. We are tearing it down and rebuilding it and appears we can save it. I have a few fuel injection parts but missing most of them. They threw in dual carbs with manifolds if I wanted to go that route. My Vin for the wagon 464 20451** shows its a late 74 car, the engine shows EC0148** and looks like its a very late 73 engine. Based on what I've seen online can't tell if it would be an L-jet or D-jet motor. Also, don't see how we could run carbs based on the pedal set up, no throttle cable, tunnel for the throttle cable, etc. I saw that they still made carburated 412's during that period. We are building a runner, not doing a high end resto like my T34 and Ghia vert so just want to get it running as cheaply as possible. Based on how much of the FI system I'm missing very concerned about going that direction. Any feedback on which FI system an EC motor should have and if its possible to do carbs on this car if we wanted would be really helpful. Really appreciate any expertise on this.
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1963 ghia convertible project

[Pepperbilly]

Hey Big Mike,

Looks like one of the dreaded California wagons with the low compression engine. These were all AFC fuel injection… Air Flow Controlled, L Jet. This has an automatic trans, correct? Too bad most of the injection parts are missing because that would be the way I’d go. I am no carb conversion expert, let Ray Greenwood chime in on this. It would be beneficial to know if anything has been done to the engine. Unless you are using the Solex carbs that were designed for the type 4, I am not sure you will be happy with the outcome.

Bill

[Big Mike Cbad]

Thanks for the note. Yes its an automatic, Engine is not original, but likely sourced close by in CA. We are doing a full engine rebuild as we speak, keeping it stock (flat pistons low compression). Since so much of the FI is missing and the electrical is a mess, would prefer to convert to carbs to save some major heartache and make it a driver. Would love some feedback from someone that's done the conversion successfully since the pedal set up looks so different than Type 1 and Type 3 VW's. I would assume its doable since there appears to have been carburated 412's during that same time period and I would assume the chassis are the same, but who knows. Also if its possible to source all the L-jet parts at a reasonable cost we are considering that as well, but I don't have the parts book showing everything we need for that era L-jet. It's really a cost and heartache issue which way we go. Type 4's are new territory so any advice would be welcome.
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1963 ghia convertible project

[raygreenwood]

[Big Mike Cbad]

Thanks for the background. I might not have dug deep enough on my car to confirm, but don't see how the carbs would work with the current pedal system and if there is a throttle cable tube (plumbing) to run a throttle cable from the pedals to the engine compartment to even do it. If I can get a parts book with the L-jet information for my car I can see if I can source the parts to go FI, but since so much of the FI is missing, no clue on the parts needed to do the L-jet on it. If anyone has the exploded view of the fi system for a 73 or 74 wagon with corresponding part numbers for the L-jet that would help. We are just rebuilding the long block currently, so have some time to decide what I'm doing. Thanks for the feedback and if any Samba folks have access to the info on the parts that would be awesome!
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1963 ghia convertible project

[raygreenwood]

[Big Mike Cbad]

Thanks Ray, that is super helpful. I'm going to do a deeper dive on the car and locate the cable tunnel. Hoping I can also get the info on the L-Jet (exploded view with part numbers) so I can do some hunting for parts and decide the best route to go based on cost and heartache. Appreciate the help.
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1963 ghia convertible project

[Lars S]

Just curious, has anyone thrown in an aftermarket EFI in a stock 411/412 ?
Could it be an alternative to searching for old (and mostly) worn components?

Lars S
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Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[raygreenwood]

[Wildthings]

The L-jet is essentially the same as the bus L-jet, using all the same parts excepting the wiring harness which is vehicle specific do to placement of the ECU. I was able to install an entire bus L-jet into my 411 sedan without much problem though.

[Big Mike Cbad]

Thank you that is very helpful to know. I think we are going to try to do the FI set up, just hoping I can track down all the parts I need for it.
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1963 ghia convertible project

[wonkipop]

californian air resources board emission certification for the 74 L jets.
(bus, 412 and 914 1..

lists all the main super important part #s etc.

all three share the same ECU and the same AFM.

the dizzys are different. (914 has the double advance/retard vac can - i know from photos that 412s only had the advance can).

probably the throttle bodies are different than the 914s. 914s have vac retard port and vac advance port on t/b either side of throttle plate. 914s had no EGR unlike the bus and the 412 which did. bus and 412 seemed to have slightly different EGR set ups and different dizzies. don't know enough about those but at least some of the parts are shared i common with 914. different intake hose between aircleaner and t/b than 914. but top half of air cleaner box is same, bottom half would be different depending on the 412 whether a variant or sedan. its possible that 914 intake hose is shared with sedan 412s as the air cleaner sat up higher in those similar to a 914. the decel valve is likely the same. pretty sure 412 has a decel. fuel pressure valve same. fuel injectors identical apart from hose on injector. 914 is curved up, 412 is flat. might have different fuel rails as a result. crankcase ventilation similar but 412 has no oil filler like 914.

you can get many of the 914 parts but some are evaporating.
for instance the dual relay that controls the fuel pump. unobtainium except for NOS and ridiculous scalper prices. but ratwell has a diagram to make one up yourself out of two relays. think the 412 has the same dual relay.

cht , cold start injector, csi control sensor, etc would be same as 914.

its a great little system L jet. but like D jet some of the parts are now all of a sudden drying up. some of the bits for the 412s might be harder to source than a 914 as less aftermarket repro interest. but what is shared can be found fairly easily.

only shared with a 74 914. the 75s changed and use a different ECU and AFM with other changes. but them that know what they are doing do seem to be able to mix and match in the combos that work,

[Big Mike Cbad]

Thank you so much for the background and parts list. This will be helpful in tracking down what we are missing once we get the long block done and are ready to get it running.
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1963 ghia convertible project

[raygreenwood]

Actually the 412 and 914's used the same TB casting. Some has slightly different drillings added.

There were 411 and 412 with D-jet and 412' with L-jet that used both single and double action advance cans. They were not "vehicle" specific....they were "location/delivery point" specific.

I have written a lot about the 411 and 412 advance cans over the years. There were a staggering range of advance cans used. There is no one "exact" advance can spec.

Add to this that there was a pretty good range of distributors used...again location, year and transmission specific....and each had several vacuum cans that may have been used....again...delivery location specific.

There were also advance cans that the dealer could and would swap in if it fixed minor running issues on a vehicle being used in a specific location or climate.

It was a performance tuning issue.

At some point in time, moving into the mid 70's...it appears that VW stopped this practice of changing what a car had on it to match the climate or altitude or temperature of a delivery location. This was probably due to emissions requirements.

Just from 1968 through the first month of 412 after August of 1972 there were six carbureted distributors and six fuel injection distributors even before getting into L-jet.
There were 6 different vacuum cans listed. Each fit roughly two distributors. It does not means they could not be used on others they were not slated for as a tuning practice.

Ray

[wonkipop]

[Wildthings]

The way I understand it, the retard can is there so you can have more intake air flow during decel and idle without having an overly high idle speed, thus helping to reduce emissions.

[wonkipop]

[wonkipop]

i had a look in the factory manual for the 914 which has a very thorough section on L jet which is hard to find for other VW models with it, but its all there for the 914 specific engines and the only thing that L jet needed for varying locations geographically was a barometric compensator. it could be fitted to cars that operated 1000 metres above sea level. or about 3,000 feet in imperial.

thats it - L jet only needs to know air density and air temp. (know thats a simplification - engine temp etc too, but in terms of the intake business its air temp and density that lets it know what the air coming in is doing).
air temp is measured by the sensor in the AFM which is just in front of the intake section into the flap chamber.

i am guessing that all the 412 original AFMs would be like the 914 and these early AFMs had non serviceable temp sensors. later rebuilt units would have had this updated.

the EFI wiring loom would be 6 pin from AFM to ECU as per 74 914s.
but it may be a different length as the ECU was in a different place in a 412.
but the plugs either end would be the same.

there is some way you can use a combo of 74 and 75. not sure i have this right but i think you can hook up a 74 AFM with a 74 six pin loom to a 75 ECU.
think thats right. not something i have ever had to do as i am still running my factory original set up. its lasted 50 years! military grade spec - testimony to Bosch and their over engineering. anyway if you had to there is a way to mix and match the AFM and the ECU but the combo only works one way.

there was no adjustment or different kinds of dizzys on the 914 L jets across the whole USA market. all the same dizzy. just whether the hose was hooked up or not. purely an emissions thing. to certify for california.

[raygreenwood]

And...bac2 t6 the wierdities of distributors for a second....and switching back to D-jet....then we have the 1.7L 914 cars that showed up with the advance can #917 stamped on the arm....with an adjusting screw to limit/adjust vacuum advance.

This also has shown up on a few of the 412 Two door with manual trans.....and I have no part number for this advance can after all these years. Its a double can...advance and retard....and advance is adjustable.

I have also used it to great effect on an L-jet injected 1.8L. Its usefulness is that if you are running higher than stock idle and/or higher than stock idle timing...just at the fringe of kicking in vacuum advance, it limits the total advance available so that you do not over advance. This was excellent for the higher compression engines.

Ray

[wonkipop]