The Official 356Talk Forum

I was searching for the cause of backing on my car and thought that maybe the left carb was leaking. I replaced the gasket above the floats then decided to check the idle jets. I noticed they didn't have o rings on them but my kit did so I added them. Suddenly the engine was reving low. I had to lean the mix screws in much more than the right side to get Max rpm.

I took them off and the rpms jumped higher??

Should I have them on both sides or not on?

Sorry forgot to say that with o rings on the mix screws were not responsive but with o rings o the engine responded to tuning

The diagram I have for the Weber 44 IDF shows 4 O-rings for the idle jets and 4 O-rings plus O-ring cups for the mixture screws.

Mike

Use the "o" rings, as without they might be sucking air causing the higher RPM. Or perhaps more fuel.
When I got my car it had 2 "O" rings on one jet and drove me nuts trying to set the idle.

The idle jet o-rings often stick to the carb body and sometimes fall off as the jets are removed. So sometimes they come out with the jet holders, sometimes they stick to the carb body, and if you aren't careful you can end up with either zero or two o-rings on 1 jet holder. They need to be there, 1 per jet holder.

+ 1 Cliff.

Could you tell the dimensions of these O-rings, please.
Inside diameter + thickness. These are metric.
Perhaps these are missing in my carbs and the reason
for the strange running problems.

C J Murray wrote: ↑Sun May 19, 2019 6:00 pm The idle jet o-rings often stick to the carb body and sometimes fall off as the jets are removed. So sometimes they come out with the jet holders, sometimes they stick to the carb body, and if you aren't careful you can end up with either zero or two o-rings on 1 jet holder. They need to be there, 1 per jet holder.

I think two is answer. As when I put them back in without my new old rings before get to the where the jet holder could be screwed there was resistance. Like it was pushing through a rubber gasket. It's very difficult to look at this area when the carbs are on the car (it's also a pain to get the idle jet out/in) but I might have a look with my mirror.

Juha I will measure them for you when I back at home but will not be until this weekend.

However, this is set with them in

https://www.ebay.co.uk/itm/Weber-40-IDF ... SwIwhWSf0M

I would agree, no o rings vacuum leak,. leaner higher idle