Tuning with jets, Power valves and an O2 guage

[Kern Dog]

Pretty cool stuff. I've never been one to embrace new technology. Hell, I'm still using AOL for my email. I do drive an 07 Ram since I need a reliable work truck.
Months ago when I was neck deep in trying to tune the car after a cam swap, I installed an AEM Wideband Air/Fuel guage. The cam swap was done in an effort to stop the detonation I was having. The engine still knocked so the guage was put in to see if I had something else out of whack. I played with different jets and power valves to get the Air/Fuel ratio into a safe area. I stopped with the tuning after realizing that nothing I was doing was curing the detonation problem.
I finally realized that after awhile that the detonation problem stemmed from this basic issue: Too high of a compression ratio for the available fuel. I went with thicker head gaskets to lower the compression to a streetable level and since they were off the car, I had the heads ported. Now with it all back together, the detonation is gone and I am back to tuning with the guage.
Up until now, I tuned my cars by the smell of the exhaust, the color of the spark plugs, the way the car ran and whether or not the engine stalled when I put my hands over the carb throat. This guage beats them all by a mile. Right after starting the car after the head gasket swap, I started tuning. The guage read I was running in the 11.0 ratio at WOT which most would call Pig rich. There was no black smoke and no smell. based on my old ways, I would have thought that I was running an ideal mixture. I've reduced the primary jets, adjusted the idle mixture screws, adjusted the timing and changed to a Rev-N-Nator ignition box. The numbers are getting closer to the goals of 14.7 at cruise speeds and 13.0 at WOT. I've read several threads about carburetor tuning and many say that it is quite possible that I may never reach the goals exactly. Some say that if you get the idle reading clean, the transition to part throttle can go rich. Its just the nature of the carburetor. I'll keep digging and hopefully get close. Already the car feels more responsive after leaning it out some. It runs stronger than ever. Since it isn't knocking at WOT, I'm able to run more advance in the distributor. If you have considered buying one of these Air/Fuel guage kits, I'd say as long as you can afford it, do it. I got 12.8 mpg on a road trip last year with the carb running 12.5 to 13.0 at cruise and 11.0 to 11.8 at WOT. Not that I built this car to sip gas, but to me it makes sense to optimize the tune and waste as little fuel as possible.

 

[62 Dart Convertible]

Subscribed. Thanks for sharing the info Greg. I am considering going the same route to jet my carbs as ideally as possible too. Is it a AEM 30-4100 you are using? Like this - (for around $200, great value!)


Did you weld the bung into the exhaust for the sensor or are you using a temporary tail pipe mount?

While I'm asking so many questions, here's some more. What was your CR before and after, and how thick are your new head gaskets?
(I'm at 11:1, and even 98 octane with octane booster ain't cutting it. :angry9

 

[WAYNES WORLD]

I swear by using the air fuel meters and have been using them for years. Guess I got tired of getting burned while pulling plugs to read. I have 3 meters, all older units but worl well. I build a lot of carbs for people and tune them in. I tell everyone the only way I'll even mess with it if they don't mind getting a bung installed. I don't care for the unit that slips into the tailpipe. I've gotten some funny readings using them.
Your goal of 14.7 may lead to some lean spots depending on engine temp and weather. Also your timming my become an issue at that a/f ratio. I try to get around 14.2 - 14.5 cruise. You can also lean out the primaries and make changes to the squirter size and accel pump cams. That way you can get the cruise nice and lean without having a light throttle stumble. After I get the carb dialed in I go back and see what the engine likes in timming.
Happy tuning!
Wayne

 

[HT413]

Great thread, subscribed. I have ZERO tuning experience so I've been thinking about going the o2 route so I can do it myself.

 

[440fish]

I was having trouble with a terrible off idle bog on the 800 Edelbrock that came on my 69 Super Bee. The local speed shop here recommended that for my application i swap out to a Quick Fuel 780 and if i purchased it from him he would offer to dial in the air/ fuel for a few bucks.

All i can say is what a great investment. While the Q/F was much better right out of the box than the Eddy the guys ended up going down 3 jet sizes after monitoring with the A/F monitor. Car is very crisp and noticeably less exhaust fumes. The fact that the monitor reads real time at all throttle settings and under sudden heavy loads is something that just cant be done by seat of the pants / plug checks.

Plus once you have the bung installed if there are any future modifications made to the engine it will be easy to fine tune.

 

[440ronnie67]

Great thread Gregory! I have also been tossing around a couple of ideas with tuning. the GTECH looks to be a winner because it has available 02 sensors and has data logging, braking , 1/4 mile times ect, not sure if its worth the price or not but I may go with that route.

 

[Moparmatt72]

The AEM is a great unit, had one on my neon srt4 helped tune it also if you want a knock sensor not sure it there is a place to put one. Normal gas will be fine but i have needed to take out the 02 sensor and clean it when using race gas. Ill be buying these one per bank to help tune. Good luck

 

[HEMI-ITIS]

Depending on your HP level and how you drive your car,DATA is very important!! When I researched O/2 sensors and data loggers,I found the race pak always came to the top of the mud.When you get into higher HP levels,the data becomes much more important.A wrong jet change at the track can be catastrophic.I've been using the *** dyno and it's cost me THOUSANDS:black_eye:

 

[Mr B Body]

When we were tuning on my brother's RR, we found out very quickly that many carbs will not allow you to get the best AFR readings. If the carb does not have adjustable air bleeds, then most people are wasting there time trying to improve the AFR. you can get close, but not dial it all of the way in. We switched over to Holley HP carbs (not the Ultra HP) and with a few hours of dyno time (less than $200 here in IN), made vast improvements in idle, part throttle and WOT performance (we had all ready tuned the engine like we always had and the engine made 470 RWHP, after tuning we were at 495 RWHP, with nothing but jet and air bleed changes). Like many of you, we were doing the plug reading, carb adjustments, etc. It took much more time and the results were not as good as just a little dyno time with AFR readings. The drivability of my brother's 495 rwhp RR was vastly improved. Anyone could drive it now. It idles nice in traffic, has no bad habits.

 

[HEMI-ITIS]

Keep in mind that O/2 sensors are a tool.Some cars will want to be a little fatter while others will like lean.
At the track your MPH will sing the final tune.:yes:

 

[Kern Dog]

Subscribed. Thanks for sharing the info Greg. I am considering going the same route to jet my carbs as ideally as possible too. Is it a AEM 30-4100 you are using? Like this - (for around $200, great value!)
View attachment 166810

Did you weld the bung into the exhaust for the sensor or are you using a temporary tail pipe mount?

While I'm asking so many questions, here's some more. What was your CR before and after, and how thick are your new head gaskets?
(I'm at 11:1, and even 98 octane with octane booster ain't cutting it. :angry9

The guage kit is the one you have listed. It came with one bung. I had the muffler guy weld it in along with another one he supplied. So far I have only tried the Oxygen sensor in the RH side.
The engine is a 440/493. I thought the CR was 10.73 based on specs I had listed here. After pulling the heads, I wanted to verify that number. It appears that my Combustion chambers were 82ccs instead of 84, the pistons sat .012 in the hole instead of the .017 I thought. In short, I was at 11.22 with the Fel Pro head gaskets. Now with the .075 Cometic head gaskets, I am down to 10.07 to one. Many guys thought the engine would run like a slug because of the loss of quench & the 1 point less compression but that is definitely not the case.

 

[splicer]

I've had an Innovate Motorsport air/fuel monitor/data logger in my 64 Polara for 2 years now and love the thing........Have used it to find perfect jet size for the drag strip(big block strokers are thirsty..LOL) and used it to adjust air bleed for part throttle cruise when car is on the street...carb is a 950 HP with adjustable everything.......
At one point, before I learned to trust this meter, I had the jets about 6 sizes too big with no visible smoke, plug fowling or poor running...car was just slower in the 1/4....learned to read the graphs, dropped the jet size and picked right back up
As a tuning aid, they are invaluable....I just need to get better at interpreting the data...

Splicer

 

[coloradodave]

HEMI-ITIS: That's a great 'wheels up' picture of your 63. Mind if I pirate it for my desktop? Man that's cool...

 

[62 Dart Convertible]

The guage kit is the one you have listed. It came with one bung. I had the muffler guy weld it in along with another one he supplied. So far I have only tried the Oxygen sensor in the RH side.
The engine is a 440/493. I thought the CR was 10.73 based on specs I had listed here. After pulling the heads, I wanted to verify that number. It appears that my Combustion chambers were 82ccs instead of 84, the pistons sat .012 in the hole instead of the .017 I thought. In short, I was at 11.22 with the Fel Pro head gaskets. Now with the .075 Cometic head gaskets, I am down to 10.07 to one. Many guys thought the engine would run like a slug because of the loss of quench & the 1 point less compression but that is definitely not the case.

Thanks for the reply Greg, exactly what I needed to know! I am thinking now of going the same Cometic route, when I have the time and inclination to pull the heads.

It seems that AFR gets the big thumbs up!

 

[HEMI-ITIS]

HEMI-ITIS: That's a great 'wheels up' picture of your 63. Mind if I pirate it for my desktop? Man that's cool...

Sure Dave:santa:That's 5lbs of boost on pump gas:icon_weed:

 

[Meep-Meep]

Glad you are getting scientific with the beast. I have been using an LM1 tail pipe gizmo but will opt for welding a bung in the collector for more accurate data. You may want to try the left header as I heard that's the side that seems to give the best measurement, presumably with our firing order. For the most part the O2 sensor in the collector is good, but if you have an exotic intake manifold, or think you are chasing fuel distribution issues, then you will need a TC probe in each header collector.

The Race Pack is exactly the system to get fuel distribution data. Also keep in mind that inlet charge temps play a huge roll when it comes to fuel distribution. The fuel should be more of a vapor with as much of the mixture getting into each cylinder equally. Too cold or too hot will affect how the fuel is suspended in the air stream. My plan is to have a TC probe in the intake plenum so I can hopefully correlate mixture strength and temperature. I will try to add to this thread myself.

 

[Theslo1]

I used to work in a performance shop, so I've used a few different brands of wide band o2's, I prefer the AEM over some of the others, I've personally had them in two of my cars. Now I just have to learn how to tune a carb for blow through.

 

[HEMI-ITIS]

My cruzin buddy has a Fast set up with 2 o2's and that seemed to work well.

 

[bobtile]

I have a dual quad setup and was wondering if anyone knew what would need to be done to get both of them in tune. They seem like they are working well by the way the plugs work, but as stated earlier, that can be misleading.

 

[62 Dart Convertible]

I have a dual quad setup and was wondering if anyone knew what would need to be done to get both of them in tune. They seem like they are working well by the way the plugs work, but as stated earlier, that can be misleading.

I second that emotion, I'm in the same boat. Has anybody seen a guide on the order in which dual quads should be tuned? Mine is a factory dual inline set up with the progressive throttle linkage.