Lancia Beta VX Weber 40 DCNF jetting/choke

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Megaera
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Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Megaera » Fri May 22, 2015 7:34 am

Hello

I am new to this forum and this is my first post.

I have recently purchased 2 x (!) Beta Coupe VXs - both 1985 (B). Both vehicles are in very good overall order - one with 36,675 miles and the other on 56,259.

My question is regarding a new Weber 40 DCNF (18950.060) which I would like to fit to one vehicle initially and - if all goes well - repeat the process with the second.

I intend to fit the carb directly onto the stock manifold? Would there be any issues doing this?

The current spec of the carb - as listed on the company site - is as follows :

32mm Venturi
4.5 Auxillary
125 Main jet
220 Air Corrector
F24 Emulsion tube
50 Idle
45 Pump jet
175 Needle valve
100 pump spill

These are all the details I have.

The cars are both 100% stock. I would not intend making any other modifications, other than fitting customs headers 4-1 with 2.5" pipe - as per recommendations by GC. Not at this point, anyway!

I would merely like to gain an improvement over the current 36 DCA and eliminate/reduce any back pressure the current manifold/exhaust system incurs.

I would be grateful for any advice regarding the jetting etc and general set up

Thanks in advance!
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Guy Croft
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Guy Croft » Fri May 22, 2015 11:51 am

Fits OK, cannot remember how well it marries to the intake duct but easy to find out.

32mm Venturi -OK
4.5 Auxillary -OK
125 Main jet - GO 145 BUT ROLLING ROAD PROVE TO BE SURE..
220 Air Corrector - GO 180 (+ AS ABOVE)
F24 Emulsion tube - OK
50 Idle - OK
45 Pump jet - GO 50
175 Needle valve - GO 210
100 pump spill - OK

G
Guy Croft, owner

Megaera
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Megaera » Fri May 22, 2015 1:07 pm

Thank you very much for your reply.

I shall carry out all of the above and report back
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Guy Croft
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Guy Croft » Fri May 22, 2015 2:40 pm

this is one on a GC engine done last year


MT VX_carb overhaul & fitment (8).JPG
MT VX_carb overhaul & fitment (8).JPG (127.42 KiB) Viewed 2137 times
MT VX_carb overhaul & fitment (7).JPG
MT VX_carb overhaul & fitment (7).JPG (117.88 KiB) Viewed 2137 times
..
Guy Croft, owner

Megaera
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Megaera » Sat May 23, 2015 8:22 pm

Thank you for posting the photos.

I have ordered the correct jets etc as per your advice - hopefully they will arrive soon.

I do have another very basic question -

Would you advise using the stock air filter and housing - or should I use a pancake/mesh type? I was considering that option - but was concerned that the air drawn into this type of filter would not be as cool as the air from the standard filter, with the intake further away from the engine.

I feel the answer is glaringly obvious and I am being a little ignorant here.........apologies!

Thanks
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Guy Croft » Sat May 23, 2015 9:56 pm

Ignorant? No. This forum is strictly non-judgemental!

it is actually a VERY pertinent question.

A suck-thru carburetted engine like yours is very susceptible to a phenomenon called 'carburettor icing', something few really understand.

In actuality it is quite simple to explain.

Air passing thru the dual venturis of a carburettor, drawing emulsified gasoline thru the main jet/emulsion tube assembly causes a drop in temperature of the gasoline. It's called, describing it loosely, 'latent heat of evaporation'.

In conditions of high humidity (your mobile phone can tell you the daily humidity - in the UK - most of the year it is 75% humidity or higher - being an island..) and low temperature ( the critical level is 12 deg C..) the combination of evaporation of the gasoline lowers the temperature in the carburettor so much that the moisture in the air freezes and blocks all the drillings in the carb. Literally, ice forms in and on the carburettor.

Cold, dense air gives more power. The inlet manifold on the VX is water heated (or to put it more correctly - coolant heated - for you MUST use minimum 33%OE Fiat Paraflu in the cooling system to keep the galleries clean and ensure effective heat dispersion..) precisely to inhibit that icing phenomenon and also to aid warm up of the intake system... if not coolant heated it takes ages and ages to warm up, wasting fuel with lots of associated popping and banging because the fuel is not atomising effectively,. not until the intake manifold and carb warm up to engine temperature anyhow..

But it does not stop there. Cold air - best power. But if you induct direct from atmosphere with a sealed intake system, in the autumn and winter, early spring months - the carb will ice up all the time. Carb icing is really bad news, It damages the piston rings very quickly because the engine sucks in raw gasoline - and if your engine grinds to a halt you can pin it on carb icing. I have personal exp of this so I know...

With the VX the problem of carb icing is made worse by the VERY high velocity of the air thru the carburettor. This accentuates the icing problem.

Inducting from underhood with a simple filter on top of the carb is a total disaster. AVOID like the plague on any installation of any kind!!

Survey the temperature up there at the level of the filter after a quick run and you will see the WHOLE intake SYSTEM is at engine temperature - or higher! 80-85-90 deg C..!

75 deg C is optimal for power and reliability and all GC engines are built with this in mind and EVERY owner briefed INTENSIVELY about it, though that said, unless the engine is installed by one of an handful of GC approved installers (John Brown Restorations in Sussex, Ian Nixon in Middlesbrough, Mario Grech Xerri in London), the chances of an engine actually ever running this way are pretty slim. Mostly I get asked, "my engine is running at 90 deg C is that OK?".... no it is not.

Why not?

Because air intake temperatures like that - even well below that - tend, in laymans' terms, to cause pre-ignition, or worse detonation, plus all the problems associated with them.. esp blown head gasket..

So what to do. Remember I am writing for the benefit of all Sara albeit that your question was a simple one.

You use a dual intake system. if you can retain the standard VX system that is 'switchable' (manually or automatically, I do not recall as I never see stuff like that) that inducts from the underhood region in the cold months but from a cool region exposed to the forward airstream in the warmer months - that is ideal.

Most of my GC VX installations require some fairly involved alterations to the intake system architecture. It may be that the original VX airbox/system is ideal for your application and should be retained. Of course you can change the filter element for a K&N or similar if you wish. The original Lancia element would have been perfectly suitable but I doubt Fiat now sell them and an aftermarket alternative (copy) is unlikey to be as good..

I hope this reply makes sense,

G
Guy Croft, owner

Megaera
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Megaera » Sun May 24, 2015 10:36 am

What a superb reply - thank you so much.

What was an area of muddled confusion, I now understand far better, thanks to the clarity and detail of your post.

I have tried - and failed - to source an original Lancia filter. According to their respective sites, neither Pipercross nor ITG have the VX listed.

I did consider some type of cold air induction system - but based on your reply, I will persevere with trying to source a suitable filter.

Would you consider the K&N restricts flow too much?

Again, many thanks for the time you have taken in explaining the basics to me.
GC_122

Guy Croft
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Guy Croft » Sun May 24, 2015 10:54 am

K&N are the best in the world..

G
Guy Croft, owner

Megaera
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Megaera » Thu Jun 25, 2015 12:56 pm

Finally, I am starting on my VX and have a couple of further queries regarding the 40 DCNF

I would appreciate any advice on what to do regarding the vacuum advance, as there is no provision on the 40 DCNF for the pipe. Having Googled this, I have read a few opinions - but nothing definitive?

Also, what should I do with the pipe at the base of the 36 DCA which goes to the scavenge pump?

I was intending to re-route and block off the various coolant pipes (base of the carb and the auto choke) and I have concerns over the aesthetics when finished. It would be very helpful to hear how others have done this?

All help appreciated

Thanks
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Guy Croft
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Guy Croft » Fri Jun 26, 2015 12:01 pm

Are you going to change to the DCNF?

Please post some photos of the things you refer to so that readers other than GC can understand what you are referring to..

thanks,

GC
Guy Croft, owner

Megaera
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Megaera » Wed Jul 01, 2015 11:47 am

Apologies for the lack of an accompanying photo. I have attached one showing the 40 DCNF (left) and my current 36 DCA (right)

After a bit more research, I have decided to leave the current set up regarding the coolant pipes into the manifold, as I fear altering this may cause starting issues.

However, I am still unsure as to the problem with vacuum advance. I have been advised to :

a) Drill the carb in "roughly the same place as the 36DCA" and utilise the pipe from the 36DCA (circled in photo). Not an option, I feel?
b) Drill the manifold, using a screw-in take-off from an old Fiat manifold. I am concerned that this is a constant vacuum, rather than timed?
c) Change/re-curve the distributor
d) Block off the vacuum at the distributor and have no vacuum advance. I have been advised that the addition of vacuum advance was merely an economy measure and is not necessary. A degree or so advance on the timing is all that is required…..

So, I have been offered many conflicting views and would, therefore, be very grateful for advice on the correct approach here.

Thank you
Attachments
40DCNF.jpg
40DCNF.jpg (139 KiB) Viewed 1882 times
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Guy Croft
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Guy Croft » Wed Jul 01, 2015 1:35 pm

Thanks!

Ignore the vacuum advance, you do not need it. No alterations to the distributor or timing are needed.

G
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Megaera
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Re: Lancia Beta VX Weber 40 DCNF jetting/choke

Post by Megaera » Wed Jul 01, 2015 7:25 pm

Brilliant....thanks. Just what I needed, a straight, simple answer!
GC_122

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