A/F (Air-Fuel) Gauge - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ebry710 · 10-06-2010, 10:50 PM

In going through the agony of determining a carburetor for my SBC 350. One thing clear, an A/F gauge gives you another set of eyes that is missing with a vacuum gauge.

Is there a better brand? Type?

Where do they install?

'72customdeluxe · 10-06-2010, 11:16 PM

Innovate lc-1 is popular, i want to go with the lm-2 for data logging capabilities. You have a bung welded in one or both pipes, then route the wiring to the gauge in a visible spot. Need a power wire aswell

ebry710 · 10-06-2010, 11:42 PM

I have a C-20 with separate dual exhaust. Does this require two gauges? or do you add a switch? or does the gauge handle the twin feeds?

'72customdeluxe · 10-07-2010, 12:41 AM

it should be pretty even side to side. if not, there's not too much you can do about it anyway as both banks draw from both sides of the manifold. You might install a bung in both sides to check for a dangerously lean condition. You can get a setup with twin feeds, costs more and is more complicated however

ebry710 · 10-07-2010, 12:45 AM

Quote:

Originally Posted by '72customdeluxe

it should be pretty even side to side. if not, there's not too much you can do about it anyway as both banks draw from both sides of the manifold. You might install a bung in both sides to check for a dangerously lean condition. You can get a setup with twin feeds, costs more and is more complicated however

Thanks, it just seems a no-brainer to be able to see what is happening every time you turn a screw or punch a peddle. Set-up for this device is the key.

'72customdeluxe · 10-07-2010, 12:58 AM

make sure of no misfires or air leaks. Misfire will show up as lean (unburned o2) and of course raw air in the exhaust is bad

dwcsr · 10-07-2010, 01:31 AM

I made a cheap setup with single wire oxygen sensors and cheap summit gages. welded a bung in each collector and wired it up. It takes longer to warm up the sensor with a single wire but 10 minutes isn't bad given the cost savings. It really helped in tuning my BBC.

AusTx68 · 10-07-2010, 06:15 AM

I never thought to add a AFR gauge but you guys have sparked my interest. I imagine the ratio changes depending on driving conditions. What is the preferred range?

dznucks · 10-07-2010, 07:00 AM

I installed an AEM A/F gauge and a vacuum gauge. I have a bung on both sides, but this isnt nessecary. The a/f gauge really helps you tune a carb.
When i first installed it i was running an edlebrock and I was able to get it to run as good as it was going to get. Not satisfied, I pulled the Demon and the Holley off the shelf that never ran right. I managed to get both of those to run much better than the edelbrock.

Below is a video I took awhile back when i was having trouble with the edlebrock. notice it keeps spiking lean at idle.

http://www.youtube.com/watch?v=fdfOosJRAtg

**Tom Vogel** · 10-07-2010, 09:03 AM

You might also want to look at FAST... thats what I went with. I used their dual setup.... there is a bung in both collectors.

**Hart_Rod** · 10-07-2010, 11:15 AM

Quote:

Originally Posted by Tom Vogel

You might also want to look at FAST... thats what I went with. I used their dual setup.... there is a bung in both collectors.

Do you have a part number and any pics of how you mounted the gauge?

**robnolimit** · 10-07-2010, 03:25 PM

I have used the Auto-meter AFR guages many times, also the Innovative. One O2 sensor is fine, Check out Motorstate for good pricing.

**Tom Vogel** · 10-08-2010, 09:02 AM

Sorry... no pics yet. Part number is 170402 for the FAST unit. I have the FAST mounting unit as well, it is number 170493.

10-06-2010, 10:50 PM	#1
ebry710 Registered User Join Date: Sep 2010 Location: Santa Rosa, Ca Posts: 131	A/F (Air-Fuel) Gauge In going through the agony of determining a carburetor for my SBC 350. One thing clear, an A/F gauge gives you another set of eyes that is missing with a vacuum gauge. Is there a better brand? Type? Where do they install? __________________ 1971 Chevy C-20 Flatbed SBC350/Turbo 350 "Torque Is Controlled Power"

10-06-2010, 11:16 PM	#2
'72customdeluxe Registered User Join Date: Jan 2008 Location: Tejas Posts: 691	Re: A/F (Air-Fuel) Gauge Innovate lc-1 is popular, i want to go with the lm-2 for data logging capabilities. You have a bung welded in one or both pipes, then route the wiring to the gauge in a visible spot. Need a power wire aswell __________________ '72 cheyenne super step, '05 long bed gmc

10-06-2010, 11:42 PM	#3
ebry710 Registered User Join Date: Sep 2010 Location: Santa Rosa, Ca Posts: 131	Re: A/F (Air-Fuel) Gauge I have a C-20 with separate dual exhaust. Does this require two gauges? or do you add a switch? or does the gauge handle the twin feeds? __________________ 1971 Chevy C-20 Flatbed SBC350/Turbo 350 "Torque Is Controlled Power"

10-07-2010, 12:41 AM	#4
'72customdeluxe Registered User Join Date: Jan 2008 Location: Tejas Posts: 691	Re: A/F (Air-Fuel) Gauge it should be pretty even side to side. if not, there's not too much you can do about it anyway as both banks draw from both sides of the manifold. You might install a bung in both sides to check for a dangerously lean condition. You can get a setup with twin feeds, costs more and is more complicated however __________________ '72 cheyenne super step, '05 long bed gmc Last edited by '72customdeluxe; 10-07-2010 at 12:41 AM.

10-07-2010, 12:58 AM	#6
'72customdeluxe Registered User Join Date: Jan 2008 Location: Tejas Posts: 691	Re: A/F (Air-Fuel) Gauge make sure of no misfires or air leaks. Misfire will show up as lean (unburned o2) and of course raw air in the exhaust is bad __________________ '72 cheyenne super step, '05 long bed gmc

10-07-2010, 01:31 AM	#7
dwcsr Hollister Road Co. Join Date: Apr 2005 Location: Houston Posts: 6,131	Re: A/F (Air-Fuel) Gauge I made a cheap setup with single wire oxygen sensors and cheap summit gages. welded a bung in each collector and wired it up. It takes longer to warm up the sensor with a single wire but 10 minutes isn't bad given the cost savings. It really helped in tuning my BBC.

10-07-2010, 06:15 AM	#8
AusTx68 Registered User Join Date: Nov 2008 Location: Italy Posts: 1,278	Re: A/F (Air-Fuel) Gauge I never thought to add a AFR gauge but you guys have sparked my interest. I imagine the ratio changes depending on driving conditions. What is the preferred range? __________________ '68 C-10 SWB 383 Stroker (Sold 3/2/2013) '87 R2500 LWB 454 TBI converted to Carb

10-07-2010, 09:03 AM	#10
Tom Vogel 2WD Jimmy Join Date: Mar 2005 Location: Davis County, Utah Posts: 2,565	Re: A/F (Air-Fuel) Gauge You might also want to look at FAST... thats what I went with. I used their dual setup.... there is a bung in both collectors.

10-07-2010, 03:25 PM	#12
robnolimit Senior Member Join Date: Jul 2010 Location: Dandridge, Tn. USA Posts: 2,226	Re: A/F (Air-Fuel) Gauge I have used the Auto-meter AFR guages many times, also the Innovative. One O2 sensor is fine, Check out Motorstate for good pricing.

10-08-2010, 09:02 AM	#13
Tom Vogel 2WD Jimmy Join Date: Mar 2005 Location: Davis County, Utah Posts: 2,565	Re: A/F (Air-Fuel) Gauge Sorry... no pics yet. Part number is 170402 for the FAST unit. I have the FAST mounting unit as well, it is number 170493.



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