Jim,

""When the engine is cold (and the temperature switch is open), power to the choke flows through the resistor, making the opening rate slower. Once the engine wams up (and the switch closes) full 12 volts is applied to the choke heater.""

That is a great idea. I am fighting this right now in the cooler 45-50 degree outside temps. If I set my choke at #3 (3 marks from the back), it is too rich to start. If I set it at 3 marks from the front, then it opens too quickly and with the carb set leaner now (14.2-14.4), it is a fight to keep it running long enough to get some temp into the motor.
I am going to test a couple more positions on the choke and maybe a larger primary squirter and see if I can get the startup a little easier in the cooler weather. If this does not work, then I might get with you on your change. I am hoping that I won't have this much cold startup problems once the outside temps go back up.

Thank you.

Good info I'm thinking of purchasing a kit soon. One question I have is these lc-1 and lm-1 kits are a single sensor correct/ which bank are you guys monitoring? Or Do you switch the sensor between banks or put the sensor in the H-pipe if so equiped?

Thanks
Gary

Gary,
I have a O2 bung welded into both of my header reducers. I am currently learning with one sensor in the drivers side reducer. My plan is once I get some tuning time with one sensor, I would like to buy a second gauge for the passenger side just so I can watch both sides. Is it overkill for the second sensor? Maybe, but I would not know for sure until I install it or move my existing sensor to the other side.

On a cold start with the choke on in park, my a/f was in the low 13's during the summer. When fall rolled around and the temps were not far above freezing, that a/f went to the low 14's. I would warm it for 30 seconds, kick it down and go. During that initial part of cold driving where my choke was still closed, I found my a/f didn't really change as the choke opened. However if I tried a cold start with the choke wired open, it would want to run very lean like 16-17:1. I was running a thermoquad at the time with the stock choke with the electric heating element disconnected. Headers, aluminum heads and a stock cast iron intake and I found it took a bit longer than necessary for the choke to open, especially compared to the stock heads w/ manifolds and a functioning exhaust heat crossover in the intake. Next time I would just do a manual choke instead.

Quote:

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Good info I'm thinking of purchasing a kit soon. One question I have is these lc-1 and lm-1 kits are a single sensor correct/ which bank are you guys monitoring? Or Do you switch the sensor between banks or put the sensor in the H-pipe if so equiped?

Thanks
Gary

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I just picked one bank and installed it. I jet both sides of the carb the same so I don't really see a reason to run two o2 sensors. Another thing I read was running an engine with an unpowered wideband o2 sensor can ruin it because soot/carbon can build up on it and without it being powered, it's heater isn't running to burn that stuff off.

If I go to two o2 sensors, they would both be permanently wired in.
My only thinking of running two was to be able to see if there was any issues with one side or the other.

Thanks

I've read that argument before, but IMO any issues that would cause an a/f variance from one bank to another is something I would notice without an a/f gauge. Unless a jet gets plugged or something it would have to be a mechanical failure of some kind to make one side get out of whack with another. I could see where having one o2 sensor per cylinder could be advantageous if you were hardcore tuning, but I'm skeptical as to the idea that one o2 sensor per bank would supply you with any new information over just a single o2 sensor.

Good point!!

I guess the idea of monitoring both banks stem from when I used to run a Six pack and the outboard carbs required stagered jetting but now I'm running a 750 holley on an M1 single plane so the jetting should be the same side to side.
I will probobly do as your doing Y07 install a bung on both sides, tune to one, then swap the sensor to see if there is any diff.
I've heard of guys installing two sensors with a switch to one gauge but as you stated the unpowered sensor may foul out.

Thanks,
Gary

i picked up this balkamp exhaust analizer a few years ago at a pawn shop for $15. handy as heck for carb tuning......

12's: Right after cold startup
13's: during the warmup (before actual running temp)
13.8-14.5: N idle (actual running temp)
Hi 13's: in D with foot on brake (example: stop light)
??.?: Stop light to light accel?
14.5: Cruise
12.5-12.9: WOT
-------------------------------------------------------------------------

I have read a few articles lately that show that 14.7 is a good goal for a steady cruising ratio. I have also read where this is too lean and it should be in the upper 13's. What ratio are you running at a steady 45-70mph or so.

Thanks

14.7 is the goal for cars with cat converters. Since we're not running those you can go leaner than that as long as your car will tolerate it without detonating, surging, etc. I tried running mine at 14.7 for a while, then went to 16 and I didn't get any difference in driveability or throttle response. With the thermoquad's easy to adjust primary metering rod tree, the cruise a/f ratio was very easy to tinker with.

I will aim for 14.7 as a target and see how it reacts. If all is well, then I will aim for the 15's and see what happens.
Thanks for the reply.

With a 4 barrel carb, would it be easier to disconnect the secondary side until I get the primary jetting/squirter/cam, pv/pvcr's, and primary WOT done?

Am I going to have any issues just running the primary side at WOT or do I need to test WOT with all four barrels?

Thanks

Do WOT with all 4 barrels. Would be pointless to try and tune the front 2 barrels for WOT considering you will never actually run it like that in the real world.

Daytona,

I can see it both ways.
I could tune the primary WOT only (once the main jets are tuned for cruise, then tweak the pvcr's and pv (2 door vs 4 door) to try and obtain the WOT number) and then hook up the secondaries and then finish the WOT tune on the secondary side, or I can leave it on 4 barrels and tune the secondary to suit. I was just curious which way would be best.

Thanks for the reply.

Get the primaries sorted for cruising first then figure out what jets in the back once the front is done.

Are you guys still seeing the 6-10 jet size difference (Holley style carb) from front to back after tuning with the 02 kits?

I think that I have my choke setup about right and after repairing my font squirter threads, I got the car started back up with minimal problems during warmup. I was able to get the neutral idle to 13.8-14.2 which I am comfortable with in 70 degree temps. One more cold startup test and I should be ready to test drive it and check the jetting.

Thanks again.

I think that I have my cold startup problem cured with the Holley Choke Delay Kit. This choke delay allowed my much leaner idle circuit to richen up long enough to get some heat in the motor.

After the engine reached running temp, I leaned out the N reading a little bit more and now I am at 13.8 on the O2 gauge in low 40's outside temps. I will lean this out some more as I drive the car, but for now I am comfortable with that reading. I noticed something that confuses me and I am looking for an answer. In N, the car was showing 13.8 on the gauge, then I dropped the car into D (with my foot on the brake) and the rpms dropped down to 850rpms (which is typical), but the O2 gauge LEANED OUT to 14.2. I was guessing that the 13.8 reading was going to go richer once I dropeed it into D with the extra load, but I was surprised to see it go lean to 14.2. Why did it do this? Is this typical?
EDIT: Am I idling in N on the transition circuit and when I put it in D, it is idling on the idle circuit?

I am just trying to understand the readings a little more before I get it out on the street and start tuning the other circuits.

Thanks allot.

To tune my auto trans car's Holley I warmed it up and put it in D with the E-brake on and tuned for a mix of best vacuum and idle quality. A stock cam will like 14:1 afr for idle, a wilder cam will want a richer mix all the way down to the high 12s because of reversion.

Don't tune the idle in N tune it in D. If it has to be 1500rpm in N just to idle at 750rpm in D look for more initial timing or a higher stall converter.