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 Old Hutcho
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| posted on July 1st, 2013 at 09:43 AM |
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Main jet?
Can anybody tell me at what revs the main jet kicks in on a stock 1600TP engine with a ICT34 carb? I dont need guesses folks, I need to know as
precisely as possible. Surely that is documented somewhere in the VW lieterature?
regards
Old Hutcho
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 matberry
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| posted on July 1st, 2013 at 09:56 AM |
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It's as much throttle possition as it is rpm, so no actual figure. Air speed through carb is totally rpm based, jets though are actuated by vacuum
which varies with throttle position. At 3000 rpm with your foot off the gas, as you apply throttle the main will begin to work at a lower rpm than in
a similar situation but at 1000 rpm. Get a gas anyliser and DIY or go to a specialist....beware tho, I've seen crazy jetting come out of some
specialised dyno tuners !!!
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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Old Hutcho
Officially Full-On Dubber
Posts: 281
Threads: 54
Registered: January 1st, 2004
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Location: Bomaderry NSW. 2541
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Mood: NSW Blues supporter to the end!
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| posted on July 1st, 2013 at 11:04 AM |
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I appreciate your reply. I have a PICT carb, not the mumbo jumbo I typed above. I also now have a gas analyser which measures through a lambda
sensor (oxygen) and I am doing it on a hard stand, not in the real world on the road. The instructions are telling me to go to 2500 rpm and measure
there. I did that and I got good readings, however, in the real world it feels doughy and I am thinking about a smaller main jet. Problem is I dont
know where to look for the point the main jet kicks in. Once I get it right on the apron, I will put it on the road and see what its like in the real
world of driving. Motor is a 1776 stocker.
regards
Old Hutcho
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matberry
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| posted on July 1st, 2013 at 12:17 PM |
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doughy sounds rich, lean will be crisp BUT too lean gets hot, then way lean is back-fire through the carb. If the engine is still relatively stock,
heads and cam, no jet changes will be necessary. I hear so often that a different engine combo needs rejetting....bollocks.
The carb is a metering device, it adds fuel to the air stream. It should be always around 14:1 Air:Fuel (I actually aim richer for increased cooling
like 13.5:1) A bigger engine draws more air....so more air travels thru the carb, but this doesn't mean the jets need to be inlarged, as the carb is
purely adding fuel tu the volume of air that goes thru it.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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68AutoBug
A.k.a.: Lee Noonan
Aircooled Master
Beetle Restorer - Experience over 138% - YIKES --
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| posted on July 1st, 2013 at 12:43 PM |
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| Quote: | Originally
posted by Old Hutcho
Can anybody tell me at what revs the main jet kicks in on a stock 1600TP engine with a ICT34 carb? I dont need guesses folks, I need to know as
precisely as possible. Surely that is documented somewhere in the VW lieterature?
regards
Old Hutcho
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Hi
SOLEX 34 PICT 3 ?
I have many VW manuals and none of them give that info..
some of the books give great drawings of the carbies working in each application and how they work.. etc including 34 PICT 3 etc
but I don't think they CAN actually tell You at what revs etc as the distributor has a large bearing on it too, especially where vacuum advance is
used..
I;ve been fiddling with a new BROSOL [Brasillian solex] H30/31 carby for months now .. and You can vary the way the carby works by the
adjustments..
Its slowly getting better to drive, and doesn't stop or have a huge flat spot anymore.. accelerator pump is working great but its not accelerating
up hills as good as it should. so more adjustment..
Mat knows all about it.. lol wish he lived closer.. lol
Best of Luck
LEE
- [size=4]Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY--- [/size]
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13bwagon
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| posted on July 1st, 2013 at 06:47 PM |
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 don't we all ! he is dreamy 
BUY A REAL BUG A PRE S BUG...
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