I tuned my Edelbrock 1406

[Rick Crunelle]

I know that a lot of people swap in the Edelbrock 1406 on the 60's Lincolns, so I thought I'd share what tuning worked best for me.

I know that every engine is unique, and even slight changes in all sorts of variables will cause different tuning needs, so I'll tell you what I've got and you can compare to your situation: It is a rebuilt 430 with the original stock internals, but the cam was reground by my builder to include just a little more overlap. Stock pistons means stock high-compression. I'm in Los Angeles, so near sea level, and the best gas we have is 91 octane that is cut with some crap to improve our smog situation. I've got the ingnitor ignition and a Flamethrower coil. A non-stock air filter housing that draws cool outside air from the cowl vents, and a K&N filter. I've got the base timing set to 9 degrees BTDC (any more and I get pinging). Everything else is stock. So that gives you an idea of what I've got.

I installed a wide-band O2 sensor so that I could dial in the carb, and here is what I found. The 1406 is supposed to be slightly leaner than the 1405 for economy... but mine was still running rich. An idea of approximately what the mix should be is: 15:1 for cruising, 14:1 for part-throttle acceleration, and 12.5:1 at WOT. The stock 1406 was giving me 13.5:1 at cruise, 13:1 under acceleration, and 10.5:1 at WOT. All too rich. So I played around with different rods, jets, and springs per the manual and here is what I found works best for me. If you pull up the calibration chart for the 1406 in the manual, I've found that number 8 works best for me. That is a jet and rod swap. I also changed the power mode staging springs to the pink ones from spring kit #1464. And finally, I went 2 stages leaner on the secondary jets. What I ended up with is 15:1 cruising, 13.7:1 acceleration, and 12:1 WOT. Note: the numbers actually fluctuate a few tenths in either direction, so my numbers are the rough average. My Acceleration and WOT sometime go richer (like 11:1) but eventually even back out. Also, I've got a slight lean condition when I first go from cruise to acceleration. It doesn't stay lean for long, so I'm going to put some miles on it and check the plugs. If I think it continues to be a problem, I will try moving the accelerator pump rod to the hole closest to the carb (it's in the middle hole now). That should give me a bigger shot of gas and hopefully clear up that initial temporary lean condition. One more note... I don't have a chassis dyno, so all tuning was done in real-world driving.

I hope that helps anyone with tuning questions. If after I put on some miles it appears to be too lean, I'll report back with changes.

[burnski]

awesome! Did you move the wideband O2 sensor from side-to-side to see if there is a difference left vs right?

[Dan Szwarc]

I know nothing of this wide and o2 sensor and would like more details on how to install it and what is needed to use it, pretty please.

[Rick Crunelle]

Pat - Unfortunately... no. I've got a bung welded into the passenger side pipe about 12" from the collector. I guess ideally I would check both sides (at the same time), but this is what I've got.

Dan - I've seen you around this forum for a long time... and you seem to know a thing or two about cars... and I've been drinking all weekend (so my judgement may be a little skewed), but I'm not sure if you are actually serious... If you are, no offense intended... let me know and I'll give you my backyard mechanic explanation...

[elcad70]

It's great to see this process detailed so well. The use of a wideband O² sensor to analyse air fuel ratios and adjust a carburettor seems to be a perfect way of obtaining maximum performance with a minimum amount of fuel. I would be very interested to see pictures of the plugs when you pull them just to see if they are the perfect brownish color.

[Dan Szwarc]

I figured the o2 sensor involved a bung on the exhaust pipe, but what sensor is used and what device is used to get a reading? Is it just a voltage or resistance converted to a ratio?

I know our classic's, and I know all the theory, but I am not so familiar with the specifics of modern hacks as I tend to be a bit of a a stocker and a purist. However, I am open to learning.

[Rick Crunelle]

Got it Dan... So you can pick up an O2 sensor (similar in shape to a spark plug) and an air/fuel gauge from any variety of manufacturers (mine is from AEM). If I'm not mistaken, the O2 sensor wire plugs are universal so any plug should work with any guage, but don't quote me on that. It also usually comes with a bung. So you drill a hole in the exhaust pipe near the collector, weld the bung on, screw the sensor in, then wire up the guage. One keyed 12v hot, a ground, then the plug that goes to the sensor. I was running it temporarily, so I just ran the wires out of the hood and through the wing window, then had the gauge next to me on the seat. It is as simple as that. When you are done, you can either leave the sensor in the exhaust pipe and tuck the plug up so it doesn't drag in the street, or you can unscrew it and screw a cap into the bung on the pipe.

The gauge reads the a/f ratio and gives you exact numbers. It tends to bounce around since the ratio is constantly changing, but it is typically only a couple of tenths in either direction, so you can get a pretty good idea where you are at.

Also, there are two types of O2 sensors... wide-band and narrow-band. My wide-band reads from 10:1 up to 17:1. Narrow-band read a much narrower range (I think only right around 14.7:1) and are of no use. The wide-band O2 sensor is a useful tool when tuning a carb, and if you don't permanently mount it, you can use it to tune multiple cars. Pat asked if I checked both sides, because ideally you would want to make sure that both sides are close. I didn't go the extra mile for this. If the carb is running properly, both sides should read the same. I'll check the plugs on both sides just to be sure.

The Edelbrock carbs are great for tuning. If you follow the chart in the manual, and plan ahead and buy a variety of rods and jets, you can easily make changes on the side of the road. Changing the rods and/or springs seriously takes about one minute. If you need to change the jets, you are looking at 5 minutes. And unlike other brands of carburator, when you change the jets, you pull the top of the carb off, so you don't end up dumping gas all over a hot engine.

[Dan Szwarc]

By collector, I presume you mean the exhaust manifold. How close is not close enough? I can easily access mine about 12-18" from the connection and would really live to properly tune my 1406. I can even do the welding, now.

I'll do my research when I am a little more motivated and ready to tune, but I was not aware of this tuning method and I thank you for sharing this knowledge with us.

[Solid]

By collector, I presume you mean the exhaust manifold. How close is not close enough? I can easily access mine about 12-18" from the connection and would really live to properly tune my 1406. I can even do the welding, now.

I'll do my research when I am a little more motivated and ready to tune, but I was not aware of this tuning method and I thank you for sharing this knowledge with us.

The O2 sensor approach is how the EFI conversion systems self-tune. I'm kind of surprised I never thought of doing it to set up a carb, but the Lincoln is the first car I've ever had a reason to mess with a carb on, just didn't click I guess. I don't see why it would care at 12-18" back, that's roughly where you'd find one on a late 80's EFI car like a BMW 325. Exhaust temp should still be high enough and reasonably consistent, and the 60's Lincolns don't have thermal reactors or anything else intended to alter the exhaust chemistry. As long as your seal is good between the manifold and the downpipe you shouldn't have any mixing screwing up the measurements. You could always spend a few bucks more for a heated one if you need to plumb it further back and want to tune across the rev range.

Ideally you would have a wide band with a heating element to maintain sensor accuracy, and then once you get it to idle, the software in the EFI system starts using that as a feedback loop for tuning at idle and while driving around. Newer cars use multiple sensors - before and after the cat so you can check emissions control function without really doing much and the car will throw errors if there is a fault. On cars with dual banks of exhaust that are not co-mingled, there will be sensors on all exhaust paths (so for example, on my 996TT there are four O2 sensors).

Anyway, on a normally aspirated car this is a pretty workable mechanism to get up and running quickly and this kind of measurement and adjustment at different revs and load/demand will give you a good consistent tune that a carb will never ever match. A carburetor is a retrograde bell and EFI is a linear aer spike. If you are running forced induction you probably want to be able to positively control boost with a manual controller or computer control (since you just are not going to be fast enough when watching the gauge and trying to modulate boost with the throttle) and you might also deliberately set the initial target A/F ratio rich under boost - do both in order to avoid detonation. This was a huge pain in the ass in ye olden days when a wideband heated O2 sensor cost a hell of a lot more and you had to do computer controlled ignition timing and duty cycle tables for the fuel injectors by hand, like early mid-90's Electromotive systems.

[Dan Szwarc]

I am loving this. I have lots to learn and will be putting this in the sticky forum.

[Dan Szwarc]

What kind Of gage do I need to use one of these sensors? I'm about to start googling, but if you have a quick link for a mid-level sensor and a basic gage needed as a starter system.

Let me reword that: Is there a basic setup you can recommend for the beginner who would like to tune his carb in this manner? Amazon is great for all things Prime.

[Rick Crunelle]

I don't have enough experience to rate the various gauges, but there are several manufacturers. I'm using AEM and it has been very good to me. My only advice is to buy it as a kit (gauge and O2 sensor together), and to buy one with a digital readout. Seeing exact numbers is much easier than watching a needle bounce around. And finally, if you can't mount it in the pipe within a foot or so of the exhaust manifold, consider spending a little more and getting a heated sensor. The sensors need to warm up, so if you mount them close to the exhaust manifold, they use the heat from the exhaust to warm up.

One more word of caution... the 1406 worked pretty well right out of the box. If you are going to start leaning out your mixture simply because I did... be careful. You can damage your engine if you run too lean. The owners manual has instructions on tuning by feel, and it is it always better to err on the side of a little rich. If you start making changes without an O2 sensor, listen for missing, pinging, and keep an eye on your plugs.

[Conv61Canada]

This is very cool and should save quite a bit of gas down the road.

Just a note: Cars started with EFI and an O2 sensor (or two if they had dual exhaust). As emissions requirements ramped up, the HEGO (Heated Exhaust Gas Oxygen) sensor came into play. It is only required to reduce the time from start-up to proper sensing. It does nothing once the exhaust gas is hot.

When OBDII came along as a requirement across the board in 1996 most vehicles had a sensor as close to the engine as possible and another after the catalytic convertor which was called a "cat monitor". It would detect if the catalytic failed or not. This required 2 for inline and 4 for V/H engines.

Now, catalytic convertors have been proven out well enough to last for the duration of the vehicle's emissions requirements that the monitors are no longer required so most cars with Inline engines will have one O2 sensor and V (or H) engines will have two (one on each bank) similar to how they started off in the 80s.

[dan468]

Is it still running well? Do the secondaries contribute to the idle at all?

Thank you

[burnski]

for anyone interested, i saw these clamp on O2 bungs on TV the other day, made me think of this project. https://www.amazon.ca/AEM-30-2355-250-N ... B003ISI6TI