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

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 !!!

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

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.

don't we all ! he is dreamy