Twin carb to single carb conversion on type 2

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mhsmuts
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Twin carb to single carb conversion on type 2

Post by mhsmuts » Tue May 14, 2019 7:11 am

Hi guys, do any of you have experience in converting the twin carbs on a type2/4 motor to a single carb?

Does it add value, what does it cost and is it easy enough to do?

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Re: Twin carb to single carb conversion on type 2

Post by retrovan » Tue May 14, 2019 10:25 am

If I may ask, why would you want to do this.??

Is your carbs not working, or can you not get them balanced.??

There is a number of guys here that can help with info should you need it.

You may find you would need to fit a box over your engine cover to hide this single carb.

Or you would have to make an exorbitant manifold system to have the carb below the engine lid.

But always wiling to help, give us more info, and we will offer suggestions.

Herman
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Re: Twin carb to single carb conversion on type 2

Post by Dawie » Tue May 14, 2019 12:03 pm

Once saw a type 4 variant with vertical box-effort stuck on top of hole cut into middle of engine lid. Underneath was single carb conversion + aircleaner, sticking up like a sore thumb into rear luggage compartment.

Do you plan to add manifold heating like the factory did on their single carb version of type127 industrial engine?
Image
Image
Do'nt assume anything- (While doing fault-finding).
"Things should be as simple as possible, BUT NO SIMPLER THAN THAT."
"If something can go wrong, it will go wrong" (Murphy's law).

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Re: Twin carb to single carb conversion on type 2

Post by Dawie » Tue May 14, 2019 12:10 pm

Factory had two versions of type 4 (type 127) industrial engine. The low power version was single carb and higher performance had twin carbs.
Image

Downgrading to singlecarb would destroy the value of a typ4 variant (in my humble opinion).
Do'nt assume anything- (While doing fault-finding).
"Things should be as simple as possible, BUT NO SIMPLER THAN THAT."
"If something can go wrong, it will go wrong" (Murphy's law).

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Re: Twin carb to single carb conversion on type 2

Post by mhsmuts » Tue May 14, 2019 5:33 pm

retrovan wrote:If I may ask, why would you want to do this.??

Is your carbs not working, or can you not get them balanced.??

There is a number of guys here that can help with info should you need it.

You may find you would need to fit a box over your engine cover to hide this single carb.

Or you would have to make an exorbitant manifold system to have the carb below the engine lid.

But always wiling to help, give us more info, and we will offer suggestions.

Herman
I have been warned that I have a challenge coming to get the two carbs set and that a single carb conversion is better. I got mine to start without exhaust but have since spent effort sorting out other work on it. (E.g. fitted an Empi exhaust, electronic ignition etc) The advice has raised some caution so I thought id investigate it in the mean time.

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Re: Twin carb to single carb conversion on type 2

Post by mhsmuts » Tue May 14, 2019 5:40 pm

Dawie wrote:Once saw a type 4 variant with vertical box-effort stuck on top of hole cut into middle of engine lid. Underneath was single carb conversion + aircleaner, sticking up like a sore thumb into rear luggage compartment.

Do you plan to add manifold heating like the factory did on their single carb version of type127 industrial engine?
Image
Image
I see what you are saying Dawie. Although setting will be simplified, the sacrifices for physical fitment and performance doesnt make sense


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Re: Twin carb to single carb conversion on type 2

Post by Dawie » Tue May 14, 2019 6:35 pm

34PDSIT carbs from a type 4 car are not the same as the kombi versions of the same carb. Car versions are simpler/ less complicated to set up. Those 411/412 carbs were spared the emission-required "third carb" afterthought system which became part of left kombi-carb.
Do'nt assume anything- (While doing fault-finding).
"Things should be as simple as possible, BUT NO SIMPLER THAN THAT."
"If something can go wrong, it will go wrong" (Murphy's law).

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Re: Twin carb to single carb conversion on type 2

Post by sean » Tue May 14, 2019 7:22 pm

mhsmuts wrote:
Tue May 14, 2019 7:11 am
Hi guys, do any of you have experience in converting the twin carbs on a type2/4 motor to a single carb?

Does it add value, what does it cost and is it easy enough to do?

Sent from my SM-G950F using Tapatalk
Why on earth do you want to do this?

You would have to butcher your car to make it work, not to mention the extra noise levels, loss of boot space and fumes entering the cabin.
Oh yes, less power as well.

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Re: Twin carb to single carb conversion on type 2

Post by mhsmuts » Tue May 14, 2019 7:27 pm

sean wrote:
mhsmuts wrote:
Tue May 14, 2019 7:11 am
Hi guys, do any of you have experience in converting the twin carbs on a type2/4 motor to a single carb?

Does it add value, what does it cost and is it easy enough to do?

Sent from my SM-G950F using Tapatalk
Why on earth do you want to do this?

You would have to butcher your car to make it work, not to mention the extra noise levels, loss of boot space and fumes entering the cabin.
Oh yes, less power as well.
I don't want to do it, I was asking as some have recommended it. Had no intention to spend money to modify something that would be worse off - hence my question

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Re: Twin carb to single carb conversion on type 2

Post by Tony Z » Tue May 14, 2019 9:11 pm

this Is likely what others have spoken about. It works ok in a kombi but it isn’t great. It is simple though.

Image

Image

There are some low profile manifolds that you can get to help either Weber ict’s or idf’s fit below the engine cover, but I think you also need special air filters too. Check out csp and Dellorto.co.uk

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Re: Twin carb to single carb conversion on type 2

Post by retrovan » Tue May 14, 2019 10:00 pm

Twin carbs are not that hard to set,

Every body is scared of the boggy man but no one has seen him, the same for the carbs,

The guys do not do their homework, and fiddle not knowing what they do, and then :bn: happens.

Start systematically, with the cleaning of the carbs, one at a time, and then follow the correct way to set them.

They have run the car perfectly for the last 40 years, I am sure you will get them to work another 40.

The forum will assist you when you get to that point, I am sure.

And if all else fails, you can fit a set of WEBER 34ICT carbs they work a treat.

good luck with your project,

enjoy

Herman
1952 Split Beetle 1835cc (Azure Blue)
1968 Fastback 2Lt.type4( Red)
1972 Low Light Bay Panel Van 2Lt type 4(White)
1975 Fleetline Panel Van 1914cc (Aqua Blue/White)
2019 MeFusco Beetle Truck

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Re: Twin carb to single carb conversion on type 2

Post by Dawie » Tue May 14, 2019 11:16 pm

How the 411/412 carbs differ from kombi versions:
Image
Left hand carb. All we have to do is use plain common sense. Adjust each side to be mechanically identical.
As in:
Throttle- stop screws: exactly identical degrees from closed. (If we want higher idle speed, adjust each side by say 25 degrees extra. So both sides always operate at the same amount of turns and degrees. (Use plain common sense to avoid choke system's idle cam from interfering with adjustment, like leaving ign on for short while to disable choke).

Idle mixture: Most 412 carbs, like type 3 carbs, have a little black "wheel" on idle screw. (Below idle cutoff valve in picture). There is a raised part. Like braille. So it can easily be adjusted by hand, and position can easily be felt even by a blind person. Also keep adjustment identical turns/degrees each side. I adjust mixture for highest idle speed when at operating temp. Then turn each screw in slightly, (richer), for a minor, barely noticeable, lower idle speed. This is to compensate for when engine is cold. Might need minor touch-up when very cold. Always keep both sides identical turns/degrees. (Kombi carbs have recessed screws).

Linkage... easy. Also adjust so that both carbs open at exactly the same time.

There is one MAJOR issue. Many/most people get confused between direction when turning screws. So they mess up the settings, sometimes without realizing.

In early days i tried syncronize by flow meter, but with these single-throat per side Solex carbs i get excellent results when simply keeping all adjustments "mechanically identical". And once adjusted, they stay that way.
The cold-idle cams (behind choke element), helps to slightly raise idle speed for first few minutes if engine is cold. (Hopefully they have not been fiddled with before). Adjustment, again, is plain common sense.
Do'nt assume anything- (While doing fault-finding).
"Things should be as simple as possible, BUT NO SIMPLER THAN THAT."
"If something can go wrong, it will go wrong" (Murphy's law).

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Re: Twin carb to single carb conversion on type 2

Post by 73type2 » Wed May 15, 2019 9:32 am

Thanks for the explanation, Dawie. I use the same approach in setting my Ponton 220S carbs. I'm not a trained mechanic but the manual is quite helpful and I manage to do most tasks on my cars. There is also YouTube.

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Re: Twin carb to single carb conversion on type 2

Post by mhsmuts » Wed May 15, 2019 10:23 pm

Dawie wrote:How the 411/412 carbs differ from kombi versions:
Image
Left hand carb. All we have to do is use plain common sense. Adjust each side to be mechanically identical.
As in:
Throttle- stop screws: exactly identical degrees from closed. (If we want higher idle speed, adjust each side by say 25 degrees extra. So both sides always operate at the same amount of turns and degrees. (Use plain common sense to avoid choke system's idle cam from interfering with adjustment, like leaving ign on for short while to disable choke).

Idle mixture: Most 412 carbs, like type 3 carbs, have a little black "wheel" on idle screw. (Below idle cutoff valve in picture). There is a raised part. Like braille. So it can easily be adjusted by hand, and position can easily be felt even by a blind person. Also keep adjustment identical turns/degrees each side. I adjust mixture for highest idle speed when at operating temp. Then turn each screw in slightly, (richer), for a minor, barely noticeable, lower idle speed. This is to compensate for when engine is cold. Might need minor touch-up when very cold. Always keep both sides identical turns/degrees. (Kombi carbs have recessed screws).

Linkage... easy. Also adjust so that both carbs open at exactly the same time.

There is one MAJOR issue. Many/most people get confused between direction when turning screws. So they mess up the settings, sometimes without realizing.

In early days i tried syncronize by flow meter, but with these single-throat per side Solex carbs i get excellent results when simply keeping all adjustments "mechanically identical". And once adjusted, they stay that way.
The cold-idle cams (behind choke element), helps to slightly raise idle speed for first few minutes if engine is cold. (Hopefully they have not been fiddled with before). Adjustment, again, is plain common sense.
Thanks Dawie. You are giving me hope!

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mhsmuts
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Re: Twin carb to single carb conversion on type 2

Post by mhsmuts » Wed May 15, 2019 10:24 pm

retrovan wrote:Twin carbs are not that hard to set,

Every body is scared of the boggy man but no one has seen him, the same for the carbs,

The guys do not do their homework, and fiddle not knowing what they do, and then :bn: happens.

Start systematically, with the cleaning of the carbs, one at a time, and then follow the correct way to set them.

They have run the car perfectly for the last 40 years, I am sure you will get them to work another 40.

The forum will assist you when you get to that point, I am sure.

And if all else fails, you can fit a set of WEBER 34ICT carbs they work a treat.

good luck with your project,

enjoy

Herman
Thanks Herman

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