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is cruise not always cruise? #964565 04/02/11 05:05 PM 04/02/11 05:05 PM
Joined: Jul 2006 Posts: 4,179 California mickm OP master
mickm OP master Joined: Jul 2006 Posts: 4,179 California	i have been using the LM-1 to dial the mixture in, and am seeing in the mid to high 12's for cruise at roughly 40mph. i took it out to the highway, and am seeing 14's at 65-70. i thought that the mixture at cruise should be roughly the same at most speeds where the engine is cruising at an even rpm. is this not so? or is something else going on?

Re: is cruise not always cruise? [Re: mickm] #964566 04/02/11 10:33 PM 04/02/11 10:33 PM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	I assume you have a carb? "cruise" is generally determined by vacuum level not rpm. They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: is cruise not always cruise? [Re: Supercuda] #964567 04/02/11 10:44 PM 04/02/11 10:44 PM
Joined: Jan 2007 Posts: 7,664 IN A ahy master
ahy master A Joined: Jan 2007 Posts: 7,664 IN	At light load meaning fairly high vacuum or "cruise" you would want the AF to be consistant and around stoiciometric (14.7). Some engines can take even a little leaner. Your lower AF at slow speed suggests carb adjustments are in order. Even at higher speed, it looks a little rich.

Re: is cruise not always cruise? [Re: ahy] #964568 04/02/11 11:41 PM 04/02/11 11:41 PM
Joined: Jul 2006 Posts: 4,179 California mickm OP master
mickm OP master Joined: Jul 2006 Posts: 4,179 California	yes, 2 4's. it is a little on the rich side. that is what i thought though, vacuum determines the mixture. just not sure why i'm seeing different values at different speeds. probably need to take a vacuum gauge and see what i'm reading at those speeds, see if anything is different there. but i'm not sure other than leaning it out slightly what other adjustments would be needed...

Re: is cruise not always cruise? [Re: mickm] #964569 04/03/11 03:44 AM 04/03/11 03:44 AM
Joined: Aug 2003 Posts: 43,349 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,349 Bend,OR USA	Real light throttle in steady state(constant RPM) cruise the higher the AFR the cleaner the motor will run. I like to see 14.2 to 15.3 at light throttle cruise with my six paks and single four barrel motors at or above 2000 RPM Is this a street hemi 2x4 stock intake or a tunnel ram 2x4 or single plane 2x4 intake? It makes a difference Also are you using a dual wide ban with sensors in both sides or a single sensor on one side?If single have you switch it form one side to the other an if so does it read the same on both sides or different? Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: is cruise not always cruise? [Re: mickm] #964570 04/03/11 09:00 AM 04/03/11 09:00 AM
Joined: Jan 2003 Posts: 1,022 Andrews,In. U.S.of A. 6 67_Satellite super stock
67_Satellite super stock 6 Joined: Jan 2003 Posts: 1,022 Andrews,In. U.S.of A.	I have the LM-2 and have noticed the same thing.I figured as long as it was "reasonable" at lower speed cruise,and it was where I wanted it (high 14's)at highway speeds,I would just run it that way. You could lean up the idle circuit and juggle main jet/air bleed combos around and probably get it better,but after how much experimentation? What is the idle mix like? At the lower cruise speed the idle circuit will make up a greater percentage of the total fuel flow.If it were richer than needed and the main jet was a little below ideal,it could account for the situation you have,leaning out as the speed increases.

Re: is cruise not always cruise? [Re: mickm] #964571 04/03/11 11:53 AM 04/03/11 11:53 AM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	Quote: that is what i thought though, vacuum determines the mixture. just not sure why i'm seeing different values at different speeds. Vacuum is generally load related, more load is less vacuum. More RPM is usually more road speed, especially at cruise, so less vacuum. As was mention, the idle mixture affects almost all aspects of you AFR, except at WOT. If it's too rich and you crutch the upper end of cruise with the PV then the mid range cruise (between idle and PV opening) will be off. I always set my idle mixture first and any change to it requires going back over the other adjustments. They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: is cruise not always cruise? [Re: Cab_Burge] #964572 04/03/11 01:46 PM 04/03/11 01:46 PM
Joined: Jul 2006 Posts: 4,179 California mickm OP master
mickm OP master Joined: Jul 2006 Posts: 4,179 California	Quote: Real light throttle in steady state(constant RPM) cruise the higher the AFR the cleaner the motor will run. I like to see 14.2 to 15.3 at light throttle cruise with my six paks and single four barrel motors at or above 2000 RPM Is this a street hemi 2x4 stock intake or a tunnel ram 2x4 or single plane 2x4 intake? It makes a difference Also are you using a dual wide ban with sensors in both sides or a single sensor on one side?If single have you switch it form one side to the other an if so does it read the same on both sides or different? it is the stage V manifold, with 2X4 edelbrocks. unfortunately i only have a bung in one side, time to put one in the other methinks. sounds like a good idea to get a better reading.

Re: is cruise not always cruise? [Re: Supercuda] #964573 04/03/11 01:49 PM 04/03/11 01:49 PM
Joined: Jul 2006 Posts: 4,179 California mickm OP master
mickm OP master Joined: Jul 2006 Posts: 4,179 California	idle is a little rich, in the 13's. i could take care of that. i wasn't aware that the idle circuit had that much influence on the cruise circuit. i thought that once into cruise it was pretty much off the idle circuit. and yes, even though i know that, i didn't take into account that vacuum is a function of load. i will play with the idle circuit a bit and see what that does. thanks for the suggestions...

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