Something I noticed is that if I am cruising with just a little acceleration I can maintain somewhere in the 18-20 AF ratio and I'll get some detonation as well of course. I get that in all gears (T5). My question is, what circuit in the carb is involved in cruising? Because that's the circuit I'm having problems with I would think.
How are you measuring your A/F ratio? I don't think gas will even burn at 18 parts of air to 1 part gas.... It sounds like you are describing manifold vacuum not A/F ratio.
there is a bung installed in the collector of the right header. we have an innovative AF gauge hooked up to an O2 sensor.
The proper cruising range is 14.2 - 14.7, Power and idle is 12.8 to 13.5 or so. If you are running a blower you better fix that lean condition FAST or you will be building a new engine.
the idle circuit has a big part in cruise mixture but it sounds like you have a vacuum leak somewhere for it to be doing it with 2 different carbs. i would check for leaks first then start playin with mixtures
so idle screws affect cruising? ok that's good to know. I'm off next 2 days. i'll go over all the vacuum lines today or tomorrow. that's a good suggestion. I did check over the carb with bryant and he did recommend some changes to the plumbing.
it effects the mixture till abou 2000-2500 rpm at cruise and contributes all the way through redline. this might help http://www.junkyardgenius.com/holley/tune01.html
At cruise the power valve is closed, vacuum is slightly higher than at idle. The secondary spring only controls when the secondary throttle plates open and they are controlled by venturi vacuum NOT manifold vacuum. At cruise the venturi vacuum is very low and the secondaries should be closed.
This is all true in an ideal world but to know for sure the conditions that control these functions are correct more info would be needed. What is manifold vacuum at cruise speed, what size power valve is in the carb, are the secondary butteflies opening due to malfunctioning, are the secondary butterflys opened too much and allowing too much of the idle tranfer slots to be exposed, is timing set correctly, how good is the valve train and valve springs. This is not a new freshly built motor and I believe he has already been told that his valve springs are weak from previous dyno session so throw therory out the door and use factual information. With all this being said non of these would cause a lean condition but could be inplay at cruise speed
the valve spring theory went out the window when mo put the holley on. with the edelbrock the motor would not rev much past 3000 rpm. with the holley it would easly go past 5000. we looked at the edelbrock the other week and there is secondary lock out lever that the choke controles and it looks like it never unlocked the secondarys.
