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Author Topic: Weber 32 DAT : new needle seat is cross drilled ...  (Read 133 times)
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Modano
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« on: August 29, 2021, 06:51:10 PM »

Hi
I'm learning (at a slow pace) basic ajustements and behaviours of the 32 DAT 3/251 I have on my 1300, which was sitting for 10 years almost.
When I got it back, the mixture was so rich that spark plugs were wet and I had a decent amount of gas in oil.
Funny fact, this carb was brand new, I installed it a year before I put my car to "sleep", hence a 3/251 while the original was a 3/250. It must have run 1000 kms at most.

So I read a lot here, on Pat Braden's and Haynes book, plus standard Lancia specs, (By the way, I've always been fascinated by carburetors and how engineers handled so cleverly all the challenges involved with mechanical only systems).
Of course it had this brownish deposits so I started with a very gentle cleaning (no full overhaul, I want to do step by step).

The first problem of this carb flooding was a damaged float. I could replace it, this was instantly better. I even had a too poor mixture as the plugs were totally dry.
Then I tried to ajust the 7 and 43 mm level (float level and max movement). Got mixed results depending of how I did the adjustement. mostly a bit rich, not as responsive as I remember. I'm pretty sure inside pipes are a bit dirty - or worse - clogged. Ultrasonic cleaning may be mandatory later on...

Anyway, one step at a time : I noticed that the needle is a little marked on the conical size, and not as smooth as it should (well I guess). The old carb had a 150 mm needle while the spec is 175, so I could not take this one. I ordered a service kit on ebay in order to change, later on the pump valve, and the power valve.

I checked thoroughly these two when I ordered....but I missed that the 175 needle (an RCA) is cross drilled Sad

I couldn't find much details about this technique...I found that 250 are cross drilled, and I guess this increases the fuel flow when the needle is opened, but in my totally newbie mind, I would suggest this may lead to a richer mixture.

So, is this a problem ? Shall I check the proper part (DAT's needle are pretty standard : Weber 79507, so no problems to find them), without the drill ?


* needles.jpeg (122.77 KB, 640x480 - viewed 69 times.)
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hutch6610
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« Reply #1 on: August 30, 2021, 12:13:10 AM »

Quote
I found that 250 are cross drilled, and I guess this increases the fuel flow when the needle is opened, but in my totally newbie mind, I would suggest this may lead to a richer mixture.

If you mean that little hole on the side in the picture then don't worry about it. It would lead to filling the bowl up a little faster and not making it rich so it should be alright so long as the float level is set correctly. Too high it will run richer and too low and it will be lean (you know that already)
As for the response the accelerator pump jet may be partially blocked, it should give a "clean squirt" of fuel into the barrel on opening the throttle, you may have not noticed it before as it was running too rich with the faulty valve/float.
Now you have it about right mixture wise you get a flat spot on opening the throttle, is that what you mean by response?



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Modano
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« Reply #2 on: September 04, 2021, 10:29:05 PM »

Hi
thanks a lot.
Yes I was wondering about this hole on the side Smiley
No problem then.
I'll close this topic and maybe open another one on where I'm headed with the 32 DAT Smiley

I'll also receive some documentations I'll share
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