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wcfvw69
Samba Purist
Joined: June 10, 2004
Posts: 13682
Location: Arizona
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 Posted: Mon Aug 04, 2025 8:24 pm Post subject: Re: Dual carbs giving me a fit |
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| skills@eurocarsplus wrote: |
The SVDA may be an issue here, as these don't usually make enough vacuum to properly use the advance, that is why you see many run a 019/010
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Exactly Don. None of the Weber dual 40's or 44's provide enough ported vacuum to work a SVDA vacuum canister. Ported vacuum is created with the throttle plate opens. Those SVDA and DVDA canisters need 200mm hg of ported vacuum to fully advance. Unless those Webers have been modified for the correct ported vacuum, your SVDA is only advancing with the mechanical advance side of the distributor.
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SGKent 
Samba Member
Joined: October 30, 2007
Posts: 42691
Location: at the beach
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| Posted: Tue Aug 05, 2025 9:13 am Post subject: Re: Dual carbs giving me a fit |
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In this scenario, my vote is that a mechanical advance distributor, curved for the carbs, engine and load would offer the best performance and ease of installation. Mileage might suffer a tiny amount compared to a proper SVDA but the lack of a proper vacuum signal and curve limits SVDA solutions. Those things said, I do not believe the cause of the carbon fouling that opened this thread is timing. I believe it is in the jetting and set up of the carbs, and the lack of experience the OP has with this.
There is no singular "kit" or jetting that is purely bolt on. John at AirCooled was very good at putting together quality bolt on carb kits but his company is gone now. Making matters worse, displacements, C/R, heads, cams and exhaust combinations are all over the place. Each needs its own tuning. I've added all that I can on this and frankly I think I am wasting my time in this thread, it is better to let the OP struggle his way thru it. Good day.
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MrVWGuy
Samba Member
Joined: February 21, 2010
Posts: 651
Location: North of Pittsburgh PA
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| Posted: Wed Aug 06, 2025 10:27 am Post subject: Re: Dual carbs giving me a fit |
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| timvw7476 wrote: |
Back in the day you could just strip an electric pump off a Honda Civic, one rated to support a Civic 70hp engine with the old CVCC Keihin carb, and it would work perfectly feeding dual tiny Webers for a Type IV engine rated at 68hp.
Problem is there aren't any old Civics from 1982 sittiing in the yards. You might have to buy an adjustable fuel regulator to get to 2 3/4 psi to your carbs.
Or find a delivery pump that actually announces it s max pressure production is under >3< . |
FYI what you can do is get Carter P90091 electric fuel pump (Amazon has it for $48.00) and it maintains 2.5 PSI and comes with a metal fuel filter & mounting bracket. If your bus was originally fuel injected it will mount in the original fuel pump location and you can even use the existing wiring as well. We run this on my wife's 76 Westy that was converted to Dual Weber 40 IDFs and it works great.
https://www.amazon.com/dp/B07BBDSZP1?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1
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borninabus
Samba R&D Dept.
Joined: May 18, 2006
Posts: 4739
Location: Arizona Highways
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| Posted: Wed Aug 06, 2025 11:49 am Post subject: Re: Dual carbs giving me a fit |
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just an FYI that the above listed carter pump has 3/8" fittings in & out.
stretching 7mm fuel lines to 9+mm is not something i would recommend doing.
i'm sure people do it all the time. YMMV
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MrVWGuy
Samba Member
Joined: February 21, 2010
Posts: 651
Location: North of Pittsburgh PA
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| Posted: Wed Aug 06, 2025 3:38 pm Post subject: Re: Dual carbs giving me a fit |
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| borninabus wrote: |
just an FYI that the above listed carter pump has 3/8" fittings in & out.
stretching 7mm fuel lines to 9+mm is not something i would recommend doing.
i'm sure people do it all the time. YMMV |
Not exactly. If you look at the specifications on Carter’s website you will see that while the inlet outside diameter is 9.5 mm (3/8”) the outlet outside diameter is 5/16” which is not too far off from the factory barbs on fuel pumps and carburetors.
It’s also the same size as the inlet barb of the Weber IDF as well.
https://carterengineered.com/electric-fuel-pump-p90091
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timvw7476
Samba Member
Joined: June 03, 2013
Posts: 2493
Location: seattle
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| Posted: Wed Aug 06, 2025 5:38 pm Post subject: Re: Dual carbs giving me a fit |
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| MrVWGuy wrote: |
| borninabus wrote: |
just an FYI that the above listed carter pump has 3/8" fittings in & out.
stretching 7mm fuel lines to 9+mm is not something i would recommend doing.
i'm sure people do it all the time. YMMV |
Not exactly. If you look at the specifications on Carter’s website you will see that while the inlet outside diameter is 9.5 mm (3/8”) the outlet outside diameter is 5/16” which is not too far off from the factory barbs on fuel pumps and carburetors.
It’s also the same size as the inlet barb of the Weber IDF as well.
https://carterengineered.com/electric-fuel-pump-p90091 |
Looks like the perfect answer. No need for regulator, constant volume/low pressure. And nothing you'll find in the wrecking/recycling yards is going to generate under 3psi! Good retrofit. |
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