Weber 34 DAT carb poor idle and second choke

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937carrera
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Weber 34 DAT carb poor idle and second choke

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Last weekend I took my DF/DG out for the first time this year, it had been started every month or two and allowed to get some heat in, but not used on the road. During this time she had run out of fuel (evaporation ?)

Amusingly after reading so many threads on here of people with idle issues with the Pierburg carb I was having problems with my Weber not idling, and more significantly it would lose power when using full throttle. This became worse after going round a corner and I concluded some dirt had got into the carbs, blocking the idle circuit and jet for the second throttle. Quite a brave guess considering I'm not great with carbs and knew nothing about the design of the carb, except it was twin choke. :)

At one point max speed was 55mph.....which converts to about 32 bhp, not much better than an early 1200cc split window T2, but it did improve allowing 70 mph or about 58hp, but still no real second choke

Today I whipped the carb off, largely to make it easier to disassemble if necessary. The water pipes were left in place and three screws removed to allow the warm up mechanism to be removed. I decided to remove both jets and clean them if they were blocked.

This was the main jet

Image

Atfer a bit of carb cleaner, 2000 grit wet 'n dry lubricated with WD40, some soft fine wire, brake cleaner and an airline it cleaned up to this. You can see that this is a 145 jet, though it said 165 on the bottom as well. It drops in just to the left of the top of the jet in the picture

Image

I then removed the other jet which was nowhere near as bad, repeated the cleaning method and noted that this was marked as a 195 jet, though it had 117 marked on the bottom. I'm assuming this is for the second choke but ran out of time to study more closely as I needed to reassemble and move the van.

I went out on a test drive, it now idles smoothly and the second choke is working. I'll need to take her on a run to make sure she's 100% but there was certainly greater induction roar and a push in the back..... well for a DF/DG T25 engine anyway.

Posting this for comment and in case it can help other Weber owners. I now know I could have removed the jets without removing the carb.
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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