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

[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

[Rustinmotion]

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

Are you sticking to a single barrel for originality or to save money? I’d go for the progressive twin barrel 32/36 but you need a new manifold

[fishyboy]

Hi rustinmotion,
I'm trying to find a compromise between originality and safety, making changes that can be easily reversed by any new owner. The two previous owner car has only done only 17,000 miles from new, still in its original paint and underseal, original fuses, never welded, all original trim etc etc. When I got the car it still had the original plug leads, distributor cap and air filter.
Phil

[Willsapples]

Hi Phil,
On my 121 it was a straight swap. Just had to file a small semicircular shape in the side of the airfilter where it slides over the carb air intake. It's described on the SKANDIX website where the carb is displayed. My 121 is an automatic so it's important that the engine doesn't stall and ticks over reliably which the Weber has done for 10,000 miles now. I did a roadtrip to Sweden back in June this year which included a lot of motorway driving. It kept up with traffic without a problem.
I see you are in Andover. I'm in north Hampshire so could meet up with you.
I haven't been very active on the forum so can't pm messages but you can Whatsapp me on 07910 962222
Cheers,
Will

[Derek UK]

The Dutch company BCCP does a Weber 34ICH conversion. It may also be the one that Scandix sells. The 34ICH comes in three choke sizes, 25mm,27mm and 29mm. The 29mm is supplied for 2.2l Land Rovers and is a common conversion and available from various sellers in the UK. The 27mm is used on the 1.5l Saab96 V4. 25mm has been used on 1.2l Vauxhall Corsa.
Take up Will's offer. The conversion isn't cheap but is correctly jetted and a simple conversion.

[Rustinmotion]

The progressive twin barrel correctly jetted with manifold is around £700 plus vat so not cheap but other than re fitting the existing air filter is plug and play
I have run cars with Webber DCOE for over 30 years and a car with twin SU for two years and my own personal experience is the SU is much more finicky to get just right
Seems like the requirement is to stay as close to original as possible so a single barrel carb is what’s required here

[grumpydad]

Hi
I dont understand you could get a second hand inlet manifold and SU for less
and it would be much easer to tune

I did that swap on a austin A35 used stuff from a morris minor
it made a great diffrence

[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.