The Ford Barn

Frank Miller · 12-06-2012, 09:22 AM

This was brought up on another thread and I asked a few questions but thought this deserved its own. Ron said he was running in the 15s and 16s for AF mixture and from what I have read it seems that would be a bit lean seeing as the stoichiometric number is 14.7 parts air to 1 part fuel. Timing was alos mentioned and I was wondering how you can tell when it is best to make a timing change or a mixture change? And last can anyone make recommendations as to what brand meter works best and what is needed?

flatjack9 · 12-06-2012, 10:03 AM

15 and 16 is not uncommon for part throttle mixtures. Not good for power.

51 MERC-CT · 12-06-2012, 10:29 AM

Speaking AF meters, anyone know what sort of readings you should get at idle?

Richard in Florida · 12-06-2012, 11:20 AM

Quote:

Originally Posted by flatjack9

15 and 16 is not uncommon for part throttle mixtures. Not good for power.

This is an important distinction. The carburetor Ol' Ron was talking about is on my engine, in a 3300 lb '53 Victoria. We're seeing 15s and 16s in easy steady cruise, but when you call for more power the A/F drops to the 12s and 13s as it should.

Old Henry · 12-06-2012, 11:31 AM

Hey. How 'bout telling a dummy what an AF meter is.

Frank Miller · 12-06-2012, 11:47 AM

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Sorry Henry. Air/Fuel mixture.

Butch11443 · 12-06-2012, 01:32 PM

I get the same readings as Richard running 2 94's. I also have a vacuum gauge which reads 13-15 at cruising speeds, 20 at idle.
Butch

Rowdy · 12-06-2012, 01:55 PM

It sounds like you guys are running alittle lean of stokeometric, which if memory serves me right is 17:1. I thought that with the bad reputation of flatheads overheating abit rich might be helpful. Say 17.5:1. I sure won't claim to be correct with todays modern fuels which change things abit. Just some random thoughts. Rod

Jack E/NJ · 12-06-2012, 02:09 PM

Butch>>>I also have a vacuum gauge which reads 13-15 at cruising speeds, 20 at idle.>>>

Out of curiosity, what units are marked on your guage? PSI, KPa, bar, etc.? Thanks.

Jack E/NJ

Rowdy · 12-06-2012, 02:12 PM

I took the time to refresh my memory and it all seems better now. Rod

Frank Miller · 12-06-2012, 03:14 PM

Rowdy number represents the air so the higher it is the leaner it is. Exact mixture is 14.7:1. Under power you want it lower and like others said art part throttle cruising you want it a little higher.

Rowdy · 12-06-2012, 03:23 PM

Like I said I had to refresh my memory as it has been 20 years since tech school, but books are still on the shelf and have to read from time to time. Rod

12-06-2012, 09:22 AM	#1
Frank Miller Senior Member Join Date: May 2010 Location: Auburn, MA Posts: 2,106	Tuning with AF meter This was brought up on another thread and I asked a few questions but thought this deserved its own. Ron said he was running in the 15s and 16s for AF mixture and from what I have read it seems that would be a bit lean seeing as the stoichiometric number is 14.7 parts air to 1 part fuel. Timing was alos mentioned and I was wondering how you can tell when it is best to make a timing change or a mixture change? And last can anyone make recommendations as to what brand meter works best and what is needed? __________________ “The technique of infamy is to start two lies at once and get people arguing heatedly over which is true.” ~ Ezra Pound

12-06-2012, 10:03 AM	#2
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,600	Re: Tuning with AF meter 15 and 16 is not uncommon for part throttle mixtures. Not good for power.

12-06-2012, 10:29 AM	#3
51 MERC-CT Senior Member Join Date: May 2010 Location: East Hartford, Ct Posts: 5,898	Re: Tuning with AF meter Speaking AF meters, anyone know what sort of readings you should get at idle? __________________ DON'T RECALL DOING SOMETHING FOR MYSELF BASED ON SOMEONE ELSE'S LIKES OR DISLIKES

12-06-2012, 11:31 AM	#5
Old Henry Senior Member Join Date: Oct 2010 Location: Orem, Utah Posts: 5,762	Re: Tuning with AF meter Hey. How 'bout telling a dummy what an AF meter is. __________________ Prof. Henry (The Roaming Gnome) "It is good to have an end to journey toward; but it is the journey that matters, in the end.” *Ursula K. Le Guin in The Left Hand of Darkness

12-06-2012, 11:47 AM	#6
Frank Miller Senior Member Join Date: May 2010 Location: Auburn, MA Posts: 2,106	Re: Tuning with AF meter Sponsored Links (Register now to hide all advertisements) Sorry Henry. Air/Fuel mixture. __________________ “The technique of infamy is to start two lies at once and get people arguing heatedly over which is true.” ~ Ezra Pound

12-06-2012, 01:32 PM	#7
Butch11443 Senior Member Join Date: May 2010 Location: Atlanta, Michigan Posts: 236	Re: Tuning with AF meter I get the same readings as Richard running 2 94's. I also have a vacuum gauge which reads 13-15 at cruising speeds, 20 at idle. Butch

12-06-2012, 01:55 PM	#8
Rowdy BANNED Join Date: May 2010 Location: Gothenburg Nebraska Just off I-80 Posts: 4,893	Re: Tuning with AF meter It sounds like you guys are running alittle lean of stokeometric, which if memory serves me right is 17:1. I thought that with the bad reputation of flatheads overheating abit rich might be helpful. Say 17.5:1. I sure won't claim to be correct with todays modern fuels which change things abit. Just some random thoughts. Rod __________________ Do the RIGHT thing - Support the H.A.M.B. Alliance!!!!

12-06-2012, 02:09 PM	#9
Jack E/NJ Senior Member Join Date: May 2010 Posts: 2,260	Re: Tuning with AF meter Butch>>>I also have a vacuum gauge which reads 13-15 at cruising speeds, 20 at idle.>>> Out of curiosity, what units are marked on your guage? PSI, KPa, bar, etc.? Thanks. Jack E/NJ

12-06-2012, 02:12 PM	#10
Rowdy BANNED Join Date: May 2010 Location: Gothenburg Nebraska Just off I-80 Posts: 4,893	Re: Tuning with AF meter I took the time to refresh my memory and it all seems better now. Rod __________________ Do the RIGHT thing - Support the H.A.M.B. Alliance!!!!

12-06-2012, 03:14 PM	#11
Frank Miller Senior Member Join Date: May 2010 Location: Auburn, MA Posts: 2,106	Re: Tuning with AF meter Rowdy number represents the air so the higher it is the leaner it is. Exact mixture is 14.7:1. Under power you want it lower and like others said art part throttle cruising you want it a little higher. __________________ “The technique of infamy is to start two lies at once and get people arguing heatedly over which is true.” ~ Ezra Pound

12-06-2012, 03:23 PM	#12
Rowdy BANNED Join Date: May 2010 Location: Gothenburg Nebraska Just off I-80 Posts: 4,893	Re: Tuning with AF meter Like I said I had to refresh my memory as it has been 20 years since tech school, but books are still on the shelf and have to read from time to time. Rod __________________ Do the RIGHT thing - Support the H.A.M.B. Alliance!!!!