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anessen

Weber carb conversion - 1.3 Polo Mk2

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anessen

Hi!

I've been meaning to get around to fixing the carb on my old Mk2, and I'm playing with the idea of doing a weber conversion. I am at the stage of working out how feasible this is in terms of parts availability. I know that there used to be whole conversions available but, of course, now there aren't... right? Although it does look like there has been a new run of the carbs themselves being produced.

 

I know that the names (DMTR/DMTL) just tell you what side the throttle is on. What do the numbers mean? Guessing venturi size, but what is appropriate for a 1.3 litre engine?

 

I can find an adaptor plate on webcon for £43, but I don't know about any of the rest of the kit (choke cable, air box mounting, studs, etc). What's a good way to go about this?

 

Sorry if I'm asking stuff that's already been answered, there's a couple of old (10 year old) threads, but it looks like things have changed a bit.

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Adim_GTI

The one you want is a Weber 32/34 DMTL carb, easy to come by and there are still firms offering the full conversion kit. You could try cobbling one together, but for the price they sell for you'd robably be best buying a complete kit
I've recently renewed my carb setup (see my build thread)

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dvderlm
21 hours ago, anessen said:

I know that the names (DMTR/DMTL) just tell you what side the throttle is on. What do the numbers mean? Guessing venturi size, but what is appropriate for a 1.3 litre engine?

32 or 34 refers to the barrel size. Inside each barrel is a venturi which the most restrictive part - it has to be because the faster air through the restriction creates low pressure that sucks fuel and air from the carb well through the carb jet stacks

(air corrector + emulsion tube + fuel jet). 

There are auxiliary venturis inside this restriction which assist this process - Bernoulli principle. 

 

The actual size of venturi is to be found in an oval on side of carb - behind choke mechanism usually. 

The 32/34DMTL with 24/25 venturis is well suited to the 1.3 Polo engine. 

This carb also has an enrichment mechanism that allows lower fuel consumption most of the time which others do not, giving economy and performance.

 

As standard Pierburg 2e3 uses 19 and 23mm venturis on 1.3 Polo.

The (discontinued) Weber 30/32DMTR replacement kit 18870975 for 1.3 Golf has only 22/22 venturis and is very responsive, with a fraction less top-end (<2bhp difference) to the 32/34DMTL..

http://www.webcononline.co.uk/library/wcimg/FittingInstructions/FL0234.pdf

 

There are 34DMTR variants with larger venturis from other cars (Citroen Lancia) which can be made to work and are worth considering if you are going to aim for high revs with longer duration or higher lift cam, or head porting, or bigger valves.

 

 

 

 

 

Edited by dvderlm
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anessen

Awesome and awesome.

 

Gonna go for a DMTL set up. I was thrown by the warning that the jets might need to be played about with but as long as I can get the car going reasonably well, I can fiddle with it.

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dvderlm

http://www.redlineweber.com/html/Tech/carburetor_set_up_and_lean_best_.htm

 

will get it right for most driving conditions, then you can pick a main jet size to match your engine (cam, compression, intake and exhaust flow).

For example fitting high flow air filter versus standard paper element often means upping the main jet by 5 from Weber specs.. 

 

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