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Deanaha
Samba Member
Joined: October 01, 2018
Posts: 25
Location: TX
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 Posted: Fri May 21, 2021 5:40 pm Post subject: DualCarb versus FI? |
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| My 1971 411 was originally a FI car, then the previous owner took that out and installed dual Solex carburetors. I have the original FI set up, but should I re-install FI or keep dual Carb? It currently runs poorly, can not keep them balanced. I am not an expert by any means but would love for this car to run smoother. |
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MarcVoss
Samba Member
Joined: July 21, 2019
Posts: 67
Location: DE, Munich
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| Posted: Fri May 21, 2021 8:55 pm Post subject: Re: DualCarb versus FI? |
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| Deanaha wrote: |
| My 1971 411 was originally a FI car, then the previous owner took that out and installed dual Solex carburetors. I have the original FI set up, but should I re-install FI or keep dual Carb? It currently runs poorly, can not keep them balanced. I am not an expert by any means but would love for this car to run smoother. |
Do you know, why the FI have been deinstalled?
To set it up again and check all components you have to be become an expert or you have to know one. There are many issues for a poor running FI engine, thats in many cases the reason, why people remove it.
Of course, if the FI is working like new, you will love it, but you will have to keep a second set of parts and / or all tools to check the components in case of problems.
Mine 411 was also running poor when I got it 2 years ago and it took some time to fix all. Finally, with a rebuild engine it is running so much better, but it has also been an investment. And I had to do all work myself, because there hadn‘t been any expert for FI around me. Maybe in the States the FI ist more common, but you have also to find somebody for help.
Good luck.
_________________
Best Regards from Germany, the origin country of Volkswagen.
Marc |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Fri May 21, 2021 10:10 pm Post subject: Re: DualCarb versus FI? |
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| MarcVoss wrote: |
| Deanaha wrote: |
| My 1971 411 was originally a FI car, then the previous owner took that out and installed dual Solex carburetors. I have the original FI set up, but should I re-install FI or keep dual Carb? It currently runs poorly, can not keep them balanced. I am not an expert by any means but would love for this car to run smoother. |
Do you know, why the FI have been deinstalled?
To set it up again and check all components you have to be become an expert or you have to know one. There are many issues for a poor running FI engine, thats in many cases the reason, why people remove it.
Of course, if the FI is working like new, you will love it, but you will have to keep a second set of parts and / or all tools to check the components in case of problems.
Mine 411 was also running poor when I got it 2 years ago and it took some time to fix all. Finally, with a rebuild engine it is running so much better, but it has also been an investment. And I had to do all work myself, because there hadn‘t been any expert for FI around me. Maybe in the States the FI ist more common, but you have also to find somebody for help.
Good luck. |
I tend to agree. While I love D-jet....between just learning to tune it (even if all of the components and wiring were brad new)....which is a BIG challenge.....and having to learn all of it PLUS work around old components, having to build a new wiring harness....and finding spares......I tell people that if you do not already have D-jet experience.........you MAY be better off going twin carbs....NEVER go single center mount carb.
The factory twin solexes ran very well. But...they have there own tuning issues....and with age like any carb, you get corrosion and worn throttle shafts that make them run poorly.
All of that said....the twin solex 411's had lower output...but mainly because they had lower compression. I beleive that was a sign of the times.
If yours were originally fuel injected and still has the domed high compression pistons.....using any good twin carb set up properly adjusted ....will run as well as the fuel injection with just about as much hp. Ray |
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Lars S
Samba Member
Joined: October 04, 2007
Posts: 786
Location: Sweden
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| Posted: Sat May 22, 2021 4:53 am Post subject: Re: DualCarb versus FI? |
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I agree with Marc and Ray, the FI you have on the shelf is likely to not function properly if you put it on....a big chance is that at least some of the injectors are stuck or leaking from its body and also there should be some reason(s) why the PO wanted to skip it.
I would look into the aftermarket FIs that are around nowdays if I had to skip the D-jet on my cars, they are not to expensive, fully tunable and some parts from the old D-jet can often be reused (throttle body, injectors etc).
I would not go to carbs in first hand but I know, you are in another situation than me since you already have a car with carbs.
Lars S
_________________
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 |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Sat May 22, 2021 7:47 am Post subject: Re: DualCarb versus FI? |
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| Lars S wrote: |
I agree with Marc and Ray, the FI you have on the shelf is likely to not function properly if you put it on....a big chance is that at least some of the injectors are stuck or leaking from its body and also there should be some reason(s) why the PO wanted to skip it.
I would look into the aftermarket FIs that are around nowdays if I had to skip the D-jet on my cars, they are not to expensive, fully tunable and some parts from the old D-jet can often be reused (throttle body, injectors etc).
I would not go to carbs in first hand but I know, you are in another situation than me since you already have a car with carbs.
Lars S |
Oh yes!......totally agree! I am always for injection over carbs. I jist stayed 8n the carb frame of mind because you have twin carbs and have the manifolds which is a big start.
As Lars is saying....if you have the stock injection runners, plenum and TB.....which are perfectly sized and well designed.....it is pretty easy to go aftermarket injection. Ray |
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Deanaha
Samba Member
Joined: October 01, 2018
Posts: 25
Location: TX
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| Posted: Sat May 22, 2021 6:37 pm Post subject: Re: DualCarb versus FI? |
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| Thank you all for the advice. I will have to find someone to get either option done. The mechanics around here are antiFI. The previous owner told me he had carbs installed because his buddy raced VWs and so that was what the "buddy" told him he needed. I will look over what parts I have to see what is missing. Are Solex good carbs? I know it will need duals just not sure if what I have is right for this car. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Sun May 23, 2021 12:25 pm Post subject: Re: DualCarb versus FI? |
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| Deanaha wrote: |
| Thank you all for the advice. I will have to find someone to get either option done. The mechanics around here are antiFI. The previous owner told me he had carbs installed because his buddy raced VWs and so that was what the "buddy" told him he needed. I will look over what parts I have to see what is missing. Are Solex good carbs? I know it will need duals just not sure if what I have is right for this car. |
Yes....solex carbs are ...stock. Yes they are good. Nothing high performance or low performance. They can be a little finicky. I cannot remember if the 411/412 twin solexes had the central idling circuit for the left hand carburetor. They are well made and dependable. However at this age they will need to be completely gone through...probably.
For injection....the stock manifolds/runners, center manifold and throttle body are totally good and can have aftermarket injection added to them pretty easily these days. Ray |
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big bus mike
Samba Member
Joined: June 16, 2004
Posts: 2230
Location: ABQ
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| Posted: Thu May 27, 2021 8:44 pm Post subject: Re: DualCarb versus FI? |
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Do you know if the engine is healthy? If the engine has low compression no amount of tuning or swapping fuel systems will help.
Perform a compression test (or have one performed) as step one. If the engine checks out as healthy, proceed with either having your carburetors rebuilt and setup correctly by someone who knows what they're doing, or convert it back to fuel injection. |
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