The Ford Barn

Flathead Fever · 03-02-2026, 12:07 AM

Thae cars with stock 02 sensors have them mounted as close to the engine as possible, so they do not cool down at idle. Also, they need to be mounted before the exhaust reaches the catalytic convertor, because it changes the exhausts reading so then it would be no good for checking the A/F reading. We're not concerned with smog, just that the A/F mixture is correct at idle and cruising. The exhaust has to heat the sensor to a certain temperature for it to work. When I was smog tech and I was watching the O2 reading I'd let it idle for a bit and I could see the readings stop producing rich lean readings. The sensor had gotten too cold to produce a signal. Later they came up with electrically heated O2 sensors that will maintain the temperature if the engine idles for too long. I've been retired from being a mechanic now for 16-years and some of this info is getting a little not as fresh as it once was since I don't do it every day like I used to. What I would do is weld an O2 bung into exhaust as close to the engine as possible to keep it hot when it was running. They sell the O2 sensor bungs for this. Then when you're not using it you can remove the sensor and out a plug in it. Just whatever you do, do not coat the treads of the O2 sensor with a lead ant seize, lead with will wipe out a O2 sensor immediately. The fumes coat the pours in the sensor, and it stops producing a voltage. That's the main reason they did away with leaded fuel. I tried it once on an old engine for fun and sure enough and the sensor "immediately" stopped producing a voltage.

One other thing we were required to have by the State of CA for smog testing was a propane bottle with an adjustable nozzle. They wanted the mixtures adjusted so that they were 50 rpm below the ideal ratio, on the lean side. Some engines would barely idle set like that. We do not want our flatheads adjusted that lean, if anything we want them adjusted slightly rich, we don't need to smog them. Still the propane bottle is an excellent way of tuning the idle mixture. If they are too lean and you run the propane bottle over the carbs the idle will go up, if it's too rich the idle will go down, if it's just right the idle won't change. You don't need all this stuff to adjust your engine; people did it long before these tools came along but it's still kind of fun to test your A/F with them. The propane bottle is also an excellent for searching for vacuum leaks. The problem is getting all these tools for one project and then having them set in your garage for another 20-years until you need them again.

Ziggster · 03-02-2026, 03:42 PM

Quote:

Originally Posted by 69a

I have a 49 F1 with a stock flat .100 over and Edelbrock heads. stock cam. I have 2 deuce on it now but only running on 1 carb. I am going to get the other carb functioning. Running Holley 94's. I was wondering what jets and what power valves most found that work? Do you set both carbs. the same jetting and power valves? I am 2300 feet elevation.

The question has been asked, what distributor are you running.
You cannot use the original Fordomatic distributor if you are using multiple carburetors.
This is because the venturi vacuum is the only way the advance system works. It has no mechanical advance. If you are using 2 X 2 carburetors you have reduced the signal to the distributor by around 50%. There are several different solutions to this, but you need to let us know what distributor you have at the moment.

I forgot the OP mentioned an 8BA. I recall reading that the stk Load-O-Matic distributors were no good for dual carb setups, but never connected the two. I guess we’re still awaiting to hear what distributor the OP is using

Bored&Stroked · 03-02-2026, 07:32 PM

Modern O2 sensors tend to me mounted 2' - 3' back from the block and they are heated to burn off any excess carbon, etc..

1952henry · 03-03-2026, 09:47 AM

286Merc, gone now, did a whole write up about using a stock LOM distributor with dual Holleys. It is possible, he actually did it. The gist of his essay, everything has to be matching in the carbs. I know there is another fella who will attest to the possibility through his experience. Cant recall his name.

Sid · 03-03-2026, 11:23 AM

The load-o-matic distributor wasn't a great distributor even in it's day. Then when you start making changes to intakes and carbs. it makes things even worst. I have not upgraded my distributor as of yet but this motor runs fantastic. great throttle response no hesitation and the exhaust don't make you cry. Only thing I can think of is maybe running the linkage progressive makes it think it is still a 2 barrel. Normally I would have done them direct but the flathead don't need that much fuel around town. We mostly put multiple carbs. on a flathead for dress up. After all you aren't going to win many races with 100 horse power. I do have the throttle blades completely closed on the front carb. Vintage Auto Garage in San Ramon Calif. offers a modified 8BA distributor with points and centrifugal and mechanical advance so it can be 6 volt or 12 volt and uses 57 Chevy points and is about $400.00. Down the line I may go this route.

03-02-2026, 12:07 AM	#21
Flathead Fever Senior Member Join Date: May 2010 Location: Yucaipa, CA Posts: 1,492	Re: 2x2 on 8BA flathead Thae cars with stock 02 sensors have them mounted as close to the engine as possible, so they do not cool down at idle. Also, they need to be mounted before the exhaust reaches the catalytic convertor, because it changes the exhausts reading so then it would be no good for checking the A/F reading. We're not concerned with smog, just that the A/F mixture is correct at idle and cruising. The exhaust has to heat the sensor to a certain temperature for it to work. When I was smog tech and I was watching the O2 reading I'd let it idle for a bit and I could see the readings stop producing rich lean readings. The sensor had gotten too cold to produce a signal. Later they came up with electrically heated O2 sensors that will maintain the temperature if the engine idles for too long. I've been retired from being a mechanic now for 16-years and some of this info is getting a little not as fresh as it once was since I don't do it every day like I used to. What I would do is weld an O2 bung into exhaust as close to the engine as possible to keep it hot when it was running. They sell the O2 sensor bungs for this. Then when you're not using it you can remove the sensor and out a plug in it. Just whatever you do, do not coat the treads of the O2 sensor with a lead ant seize, lead with will wipe out a O2 sensor immediately. The fumes coat the pours in the sensor, and it stops producing a voltage. That's the main reason they did away with leaded fuel. I tried it once on an old engine for fun and sure enough and the sensor "immediately" stopped producing a voltage. One other thing we were required to have by the State of CA for smog testing was a propane bottle with an adjustable nozzle. They wanted the mixtures adjusted so that they were 50 rpm below the ideal ratio, on the lean side. Some engines would barely idle set like that. We do not want our flatheads adjusted that lean, if anything we want them adjusted slightly rich, we don't need to smog them. Still the propane bottle is an excellent way of tuning the idle mixture. If they are too lean and you run the propane bottle over the carbs the idle will go up, if it's too rich the idle will go down, if it's just right the idle won't change. You don't need all this stuff to adjust your engine; people did it long before these tools came along but it's still kind of fun to test your A/F with them. The propane bottle is also an excellent for searching for vacuum leaks. The problem is getting all these tools for one project and then having them set in your garage for another 20-years until you need them again.

03-02-2026, 07:32 PM	#23
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,906	Re: 2x2 on 8BA flathead Modern O2 sensors tend to me mounted 2' - 3' back from the block and they are heated to burn off any excess carbon, etc..

03-03-2026, 09:47 AM	#24
1952henry Senior Member Join Date: May 2010 Location: North Dakota Posts: 1,840	Re: 2x2 on 8BA flathead 286Merc, gone now, did a whole write up about using a stock LOM distributor with dual Holleys. It is possible, he actually did it. The gist of his essay, everything has to be matching in the carbs. I know there is another fella who will attest to the possibility through his experience. Cant recall his name. __________________ I dig coal, which provides motivation for EVs. Last edited by 1952henry; 03-03-2026 at 07:47 PM.

03-03-2026, 11:23 AM	#25
Sid Senior Member Join Date: May 2010 Location: Rathdrum Idaho Posts: 780	Re: 2x2 on 8BA flathead The load-o-matic distributor wasn't a great distributor even in it's day. Then when you start making changes to intakes and carbs. it makes things even worst. I have not upgraded my distributor as of yet but this motor runs fantastic. great throttle response no hesitation and the exhaust don't make you cry. Only thing I can think of is maybe running the linkage progressive makes it think it is still a 2 barrel. Normally I would have done them direct but the flathead don't need that much fuel around town. We mostly put multiple carbs. on a flathead for dress up. After all you aren't going to win many races with 100 horse power. I do have the throttle blades completely closed on the front carb. Vintage Auto Garage in San Ramon Calif. offers a modified 8BA distributor with points and centrifugal and mechanical advance so it can be 6 volt or 12 volt and uses 57 Chevy points and is about $400.00. Down the line I may go this route.