Amazon: Swopping a Zenith 36VN to a Weber 34 - Any views?

[Othen]

Originally Posted by fishyboy

Hi all,
Given the rather leaky nature of the Zenith 36VN on my 1966 131 (https://www.volvoforums.org.uk/showthread.php?t=336115 and https://www.volvoforums.org.uk/showthread.php?t=312839) I am thinking about replacing it with a Weber 34 (https://www.skandix.de/en/spare-part...4-kit/1022670/), which seems to be a straight swap for the B18A engine.

Only minor modification is required to the rubber seal with the Volvo air filter and the actual filter (https://www.skandix.de/en/documents/...er-34/3000188/).

Has anyone any experience of making this swap. I found only one reference on the forum (Willsapples - https://www.volvoforums.org.uk/showthread.php?t=334485) but was rather hoping other users might have made this swap.

One question I have is that the Weber 34 has a 34mm throat size (where it joins the manifold) whereas the VN36VN is 36mm. Presumably this difference of 2mm should not cause any issues.

Phil

There has been some interesting discussion here Phil... here is my tuppence worth. I've just read your other thread, and my course of action would have been exactly as you have done: to get the original Zenith 36VN working properly. You seem to have achieved that (well done), but you still describe the issue as a 'ticking time bomb' - so you still aren't happy with it.

If that were my situation I certainly wouldn't start fitting other 50-60 year old Volvo carburettors, manifolds, controls and exhaust parts - the chances are that some of them wouldn't work properly and lead to an even more complex problem with non-standard parts on your Amazon. In that case the best solution (in my humble opinion) would be to fit a modern direct replacement (the Weber 34 you suggest, and a correspondent (Willsapples) in the discussion above confirms is a good fit and has worked well for the 10,000 miles). I notice the cost would be around £300, which seems expensive (to me, but then I'm a tightwad), but as it is a direct replacement there will be no further integration costs.

So, if it were me I'd stick with the original Zenith (now that you have fixed it), but if you aren't happy with it I'd go for the modern replacement (Weber 34) that a member of this excellent forum has confirmed is a direct swap. I certainly would not countenance fitting a twin choke carburettor in the hope of squeezing a few more horsepower from motor - that would be an expensive mistake.

I should add that I do not have any direct experience of this issue: my Amazon has the B18D motor with twin SU carburettors (which are easy to adjust and work very well - just as Mr Volvo intended 60 years ago).

Alan

[fishyboy]

Hi all,
I ordered the Weber 34 from Skandix (https://www.skandix.de/en/spare-part...4-kit/1022670/) on the 13th December and it arrived today. 16 days from Germany to my door over the Xmas period was pretty good. The costs worked out £239+£33 shipping, and I paid an additional £10 import duty(!), £52 VAT and a £12 "clearance fee' bringing the total cost to £311.

Hopefully, I'll get it installed over the next few days and report back.

Phil

[Derek UK]

34 ICH. What is the number in the circle moulded in the casting on the opposite side of the carb as pictured? I suspect that you won't want to do this but it would be good to have a list of all of the jets fitted to this carb.

[fishyboy]

Originally Posted by Derek UK

34 ICH. What is the number in the circle moulded in the casting on the opposite side of the carb as pictured? I suspect that you won't want to do this but it would be good to have a list of all of the jets fitted to this carb.

Hi Derek - Could you explain why I wouldn't want to do this?
Phil

[Derek UK]

Most people don't usually disassemble their new parts before fitting them! My comment based on the possibility of correctly jetting the readily available 34ICH carbs to suit the Amazon. For example, I have a couple of 29 34's and a 27 34. New but bought at reasonable autojumble prices. The 29 is usually used for bigger engines, Land Rover and Vauxhalls about 2.2l. That would make it too big for B18 and most wouldn't want it on a B20 with the old B18a manifold. If yours is a 27, knowing the jetting would mean it could be converted for the same application as yours although the original type B18a Zenith manifold with single exhaust outlet isn't the best choice. Changing to the later twin out exhaust type with semi side draught Stromberg gives a useful boost to power but that's not the route you are taking.

[fishyboy]

Hi Derek
Thanks for the information. The Weber 34ICH carb from Skandix is a 29mm venturi and I am guessing (I'll ask Skandix directly next week) it comes in the the standard settings (165 main jet, 50 idle jet etc) which is supposed to be 'most suitable for engines in the range 1700 to 2250cc"! Will ("Willsapples") mentioned earlier in the thread that his 34ICH worked straight out of the box so I'm hoping for the same.
Phil

[fishyboy]

hi all,
Added the Weber 34ICH last weekend and managed to get out for a drive yesterday. Both the car and carb performed admirably. No leaks, good acceleration and top speed. I had to make a couple of small adjustments to the air filter and rubber seal at the top of the carb body. Only required a small adjustment to the fuel mixture resulting in nice plug colours. All -n-all I am really satisfied with this upgrade.
Phil