Autolite 2100 jetting for ethanol blend

[oldiron]

I finally got around to removing that horrible edelbrock 600 monstrosity off my engine, sourced a 2 bbl intake, and built an awesome little 2bbl carb. The Bronco has really come alive with the 2100, better starts, idle,throttle response, acceleration, etc.etc.
I used 48f main jets in the build... if my math is right I should be in great shape. Anyone have any experience experimenting with different jet sizes to compensate for E/10. I don't want a lean condition/ long road trip problem.
Greg

 

[Broncobowsher]

With all the small variables possible, I would recommend just investing in a wide band O2 in the exhaust and tune off that. You get what you need, not what someone else needs.

 

[jckkys]

Originally the 2100s with 1.08" venturis, had 46-47 jets. The 48s should be able to compensate for the ethanol. So I think you're in good shape.

 

[73azbronco]

Not much difference jet wise for the fuel, but seals, now thats the problem.

 

[Joe473]

I finally got around to removing that horrible edelbrock 600 monstrosity off my engine, sourced a 2 bbl intake, and built an awesome little 2bbl carb. The Bronco has really come alive with the 2100, better starts, idle,throttle response, acceleration, etc.etc.

I used 48f main jets in the build... if my math is right I should be in great shape. Anyone have any experience experimenting with different jet sizes to compensate for E/10. I don't want a lean condition/ long road trip problem.

Greg

Read the plugs, is the engine stock cam, compression, exhaust? If cam is not stock take idle vacuum reading for getting power valve right as well.

Sent from my SM-G960U using Tapatalk

 

[blubuckaroo]

Just make sure your 2100 isn't actually a 2150. Many 2150s were jetted for the EGR system.

 

[oldiron]

Definitely a 2100. Thanks for the replies guys. I'd love to run nothing but 100% gasoline, but it's getting harder to come by around here, and I want to use this one as a daily driver/road trip vehicle, so readily available fuel is a must.
Greg

 

[WheelHorse]

Install a wideband...light cruising low 15's and I mean light and low rpm.

Down the highway, 14.2

WOT 12.2

I played with jetting up and down and I can't remember what I have, but I live by the wideband. My spark plug looks as good as an injected plug.

 

[jckkys]

When you depend on an A/F meter you are also depending on someone's idea of what is ideal for your engine. I prefer to let the engine performance parameters determine what is ideal. Long established carburetor tuning procedures establish the best A/F ratio for your engine, not a one size fits all formula. Some give better MPGs with lean mixtures that cause other engines to over heat. The combination of jet size and power valve channel restriction orifice size are what produce maximum full throttle power. A stopwatch and speedometer are the best instruments to tune this. If 48f jets work for your engine, there's no need to waist money on a wide band or other A/F meter.

 

[Broncobowsher]

A stopwatch and speedometer will tune full throttle. Wide band will tune part throttle and economy.

 

[jckkys]

An A/F gauge is a helpful tool. It isn't the be all and end all of carburetor tuning and I see little reason to modify the exhaust to install a bung for an oxygen sensor and buy an expensive wide-band A/F gauge. The 2100s sold on EB 289-302s were calibrated for a specific engine size in specific vehicle with a specific transmission. Heavier vehicles need a richer mixture so do automatic transmissions. Marine engines need an even richer mixture. The recommended ratios of the A/F gauges don't take these or many other factors in consideration.

 

[vintage bronco]

Generally 2 sizes larger than stock is how I set them up to compensate for the poor gas.

 

[broncnaz]

Yes there is some science to getting jetting its best and it is or can be different for similar engines/vehicles. Bottom line is math really wont do the work. An A/F ratio gauge is really helpful and reading the spark plugs is a must then determining how your vehicle responds to changes and if it suits you and your driving style.
Usually jets that are 1 size bigger or smaller will really not make much of a change. Stock jetting on these old carbs was pretty much a coverall. they mass produced the engines and put them in different vehicles the carbs were jetted to bolt on and run thats about it. Yes some carbs were jetted differently for different vehicles but it was still a coverall nobody at the factory tuned each carb to each engine other than maybe idle mixture and idle speed. So even the factory setting could be lean or rich at the time but with todays fuels they should all be leaner and may need even more jetting.
Also keep in mind they are trying to if they havent already to get E15 as the new standard year round fuel. So leaner again,.

 

[chrlsful]

all good.
"...take idle vacuum reading ..." I like it for more than just idle,
A/F helps.
plugs, but I like a 'plug chop' best.
recurve dizzy as cherry on top (ign is a major factor, carb is 2ndary).
Testing under different conditions: cruse, load (like a hill), WOT, watch'n distance, different octane...

Have fun w/it - I feel like a lill scientist...

Happy 4th !