wide band AFR
- Thread starter Brian
- Start date
Talkwrench
Well-known member
I'm not expert , but I'd say your a bit rich on cruise and tad lean on power.. jet and P/valve accordingly and try W setting.
If "under load" means wide open throttle and if the timing is not slow the main jets might need reduced and PV might then need slightly upsized.
The average best power at WOT of all the Flathead engines I have tested the A/F ratio was 13.2. However, there can be differing readings from meter to meter.
The average best power at WOT of all the Flathead engines I have tested the A/F ratio was 13.2. However, there can be differing readings from meter to meter.
Lawrie
Well-known member
Brian, we set up the 33 and Model a with the 97.s on with the A/f meter.my boy is away working at the moment but can find out what we settled on,I know both go very well,but both only have the one carb.
we used an inovate one,we have a real deadly one on the dragster(racepak) and that is great with a logger onto an SD card,makes tuning real easy.
Lawrie
we used an inovate one,we have a real deadly one on the dragster(racepak) and that is great with a logger onto an SD card,makes tuning real easy.
Lawrie
Bent-8
Junior Member
Brian,
I've run EFI on my flathead for several years now. I can tell you that you likely can run quite lean during cruise with no problems. I run around 15:1. I target 12:8 under full throttle, which seems to work best for my set up. It likes to idle at around 14:1 or so.
Of course, tuning is dependent on your particulars (engine specs, car weight, transmission, gearing, ect). All these factors play a role in your tuning. I'm running a mild cam, electronic ignition, and 5 speed trans in a light weight rpu.
Something else to consider, tuning is much easier with EFI. I make tuning changes while driving and can feel the immediate effects. This makes it much easier to determine what the engine wants, something you can't do with carbs. But, tuning a carb is still the same. Make a change and see what it does. JWL was right on in his post above:
At least you have a wideband. Its absolutely the best tool to use for tuning. No more guessing. It will tell you if your changes work. I don't know if you have the ability with your wideband, but if you do, datalogs are your friend.
I've run EFI on my flathead for several years now. I can tell you that you likely can run quite lean during cruise with no problems. I run around 15:1. I target 12:8 under full throttle, which seems to work best for my set up. It likes to idle at around 14:1 or so.
Of course, tuning is dependent on your particulars (engine specs, car weight, transmission, gearing, ect). All these factors play a role in your tuning. I'm running a mild cam, electronic ignition, and 5 speed trans in a light weight rpu.
Something else to consider, tuning is much easier with EFI. I make tuning changes while driving and can feel the immediate effects. This makes it much easier to determine what the engine wants, something you can't do with carbs. But, tuning a carb is still the same. Make a change and see what it does. JWL was right on in his post above:
At least you have a wideband. Its absolutely the best tool to use for tuning. No more guessing. It will tell you if your changes work. I don't know if you have the ability with your wideband, but if you do, datalogs are your friend.
john in illinois
Well-known member
If you have JWL's book, he has a section on 2 97s on a stock flathead. He points out that at higher the rpms the mixture becomes leaner and that you have to make sure you are rich enough for your max rpm.
I drove at 40 50 60and 70 and recorded A/F readings at steady throttle. This does not involve the power valve for my set up -high gear rear end. I was getting detonation due to lean mixture and jetting by this method eliminated that.
John
I drove at 40 50 60and 70 and recorded A/F readings at steady throttle. This does not involve the power valve for my set up -high gear rear end. I was getting detonation due to lean mixture and jetting by this method eliminated that.
John
scicala
Well-known member
Using a vacuum gauge along with the AFR meter is the best way to indicate part throttle cruises and what load you are at. Need to know warm idle vacuum to establish the level of the load. With a stock camshaft I would say when cruising at steady state flat ground you would not quite want the power valve enrichment at about 13" hg.
Sal
Sal