thumbs up to Affordable Injection.

[lcwizard]

probably 7, no more than 10. Optimum situation is peak cylinder pressures about 15 degrees after top center to get the best leverage from the crank journals. Too much advance and you may not get there at full burn. You will also likely have overheating issues with too much advance.
Advancing a spark can give you more top end power but at the cost of low end power. Even if your 2F could run at 6000 rpm, I'd still think 10-12 degrees max would
work best. Since most 2F motors are low RPM there's no reason I can see to bringing it over ten unless you've changed out to some other cam that might
need it or the stock cam is installed improperly.
If the AFI system has spark control ( mine didn't) there could be some programing that wants more advance at idle then pulls it back when you accelerate .
Generally, a system like that would, like a stock GM TBI, have a distributor disconnect for the computer advance, to set initial timing. There's black on tan wire in
a GM TBI that gets disconnected to set initial timing. Once it's set about 6~7 degrees, when you reconnect, the computer will jump the advance a little and control the
advance curve throughout the operating range. The stock systems use a knock sensor as a precaution against bad gas or too much initial timing to control pinging
and save your pistons from early retirement

 

[White Stripe]

The ecu programmer sets a initial advance setting. Let's say it's 26 degrees as stated. You install the efi, then go through the operation of setting your base timing to 26 degrees. Then the ecu has a reference at which to advance or retard timing. If you set it to 10 degrees initial advance, the ecu assumes the initial timing is 26. That's 16 degrees less than 26. The consequences would be for example your driving down the road at 55mph, 40kpa manifold pressure, 2400rpm. In that scenario the ecu commands I'm guessing 35 degrees of advance. But since you set initial advance to 10 degrees then you get 35-16=19. So you get 19 degrees of advance because you set the initial timing at 10. So basically your entire timing curve will be off by 16 degrees of retard from where the timing curve was actually programmed to be if that makes sense.

 

[lcwizard]

The ecu programmer sets a initial advance setting. Let's say it's 26 degrees as stated. You install the efi, then go through the operation of setting your base timing to 26 degrees. Then the ecu has a reference at which to advance or retard timing. If you set it to 10 degrees initial advance, the ecu assumes the initial timing is 26. That's 16 degrees less than 26. The consequences would be for example your driving down the road at 55mph, 40kpa manifold pressure, 2400rpm. In that scenario the ecu commands I'm guessing 35 degrees of advance. But since you set initial advance to 10 degrees then you get 35-16=19. So you get 19 degrees of advance because you set the initial timing at 10. So basically your entire timing curve will be off by 16 degrees of retard from where the timing curve was actually programmed to be if that makes sense.

Wouldn't it be odd to set an initial advance of 26 when the motor has a low lift, low duration cam? Setting it at 26 then figuring in another 15-20 degrees of mechanical\vacuum advance , you'd be stressing the motor. I'm assuming AFI doesn't control spark, but they might. If it doesn't control the spark, what it assumes
as a set timing would be irrevevant other than leaning or richening a mixture for the burn. That would just confuse the O2 sensor.
I've always tried to keep total advance between 35 and 40,depending on compression. At 26 initial, if that number is with vaccuum advance disconnected, I would think it would struggle turning over to start.
I can't say I've ever had a motor that needed more than 12 degrees initial

 

[wngrog]

I had some clown Jeep mechanic turn the timing up to 30* on a 2F because they did not know about the switched 12 power to the Aisin carb just so it would idle.

The (also) clown owner took it on the interstate and it got so hot the dissy side it the motor was glowing red

 

[White Stripe]

Wouldn't it be odd to set an initial advance of 26 when the motor has a low lift, low duration cam? Setting it at 26 then figuring in another 15-20 degrees of mechanical\vacuum advance , you'd be stressing the motor. I'm assuming AFI doesn't control spark, but they might. If it doesn't control the spark, what it assumes
as a set timing would be irrevevant other than leaning or richening a mixture for the burn. That would just confuse the O2 sensor.
I've always tried to keep total advance between 35 and 40,depending on compression. At 26 initial, if that number is with vaccuum advance disconnected, I would think it would struggle turning over to start.
I can't say I've ever had a motor that needed more than 12 degrees initial

My above comments were only for tbi with ecu controlled spark avance, not vacuum advance. Im pretty sure afi has spark control and a distributor they supply.

 

[JG2625]

Yes
Basically you set timing to 6 or 7 degrees and when you plug in the computer it advances timing to 26 degrees at 800RPMs and 35 degrees at 2000rpms. My issue is on the first start of the day. It runs rough and has a very erratic idle and will also ping under load. It only does this for a minute or two max then will settle down to the right idle RPMs and run great. Just don’t understand why it’s doing this

 

[White Stripe]

Yes
Basically you set timing to 6 or 7 degrees and when you plug in the computer it advances timing to 26 degrees at 800RPMs and 35 degrees at 2000rpms. My issue is on the first start of the day. It runs rough and has a very erratic idle and will also ping under load. It only does this for a minute or two max then will settle down to the right idle RPMs and run great. Just don’t understand why it’s doing this

I'm not sure about the timing setting. That's something you have to take up with AFI and could be dependent on they're tune. As far as rough start I would think a manifold gasket could be the culprit. With all pre obd2 efi I recommend installing a wideband gauge as well.

 

[lcwizard]

My above comments were only for tbi with ecu controlled spark avance, not vacuum advance. Im pretty sure afi has spark control and a distributor they supply.

that would make sense. The AFI I installed about 5 years ago didn't have spark control. . Nor did the previous Howell. I modified a 3FE distributor from a 62 rather than
buy a DUI ecm controlled HEI distributor to work with the GM takeoff system

 

[lcwizard]

Yes
Basically you set timing to 6 or 7 degrees and when you plug in the computer it advances timing to 26 degrees at 800RPMs and 35 degrees at 2000rpms. My issue is on the first start of the day. It runs rough and has a very erratic idle and will also ping under load. It only does this for a minute or two max then will settle down to the right idle RPMs and run great. Just don’t understand why it’s doing this

They go through a learning curve. Most system require you drive them a specific distance where they develop their running parameters. They should remember that
set off data and keep it for future starts. If all you've done is start it for a couple minutes and shut it down , you may try taking it out for a 15 minute run through the neighborhood

 

[White Stripe]

that would make sense. The AFI I installed about 5 years ago didn't have spark control. . Nor did the previous Howell. I modified a 3FE distributor from a 62 rather than
buy a DUI ecm controlled HEI distributor to work with the GM takeoff system

Yeah I haven't messed with a tbi ran with vacuum advance for a while. So I dont remember how to set it up for vacuum advance anymore. There is a company that will modify the tbi ecu so it is flashable and therefore much easier to fine tune by most tuners for around 400 bucks. Totally worth it in my opinion. I've programmed the chips in the stock gm ecu, it's a pain. Very slow and tedious process to change things. Although at that point the sniper might just make more sense...or LS swap.

 

[JG2625]

They go through a learning curve. Most system require you drive them a specific distance where they develop their running parameters. They should remember that
set off data and keep it for future starts. If all you've done is start it for a couple minutes and shut it down , you may try taking it out for a 15 minute run through the neighborhood

I have disconnected the battery to reset the computer and drove the 40 for about an hour and still have the same issue. I have a call into AFI to see if they can help me out.

 

[jembourbe]

I've been using TBI on my 2F with a Mega/Microsquirt ECU (running fuel-only) and a mechanical/centrifugal advance distributor (idle timing set on the BB) for about 20 years with zero issues. So simple. What do people get out of trying to make the GM brain work on a tractor engine, other than frustration?

Edit: maybe for gm engine conversion?

 

[lcwizard]

Yeah I haven't messed with a tbi ran with vacuum advance for a while. So I dont remember how to set it up for vacuum advance anymore. There is a company that will modify the tbi ecu so it is flashable and therefore much easier to fine tune by most tuners for around 400 bucks. Totally worth it in my opinion. I've programmed the chips in the stock gm ecu, it's a pain. Very slow and tedious process to change things. Although at that point the sniper might just make more sense...or LS swap.

basically , the old TBIs without a spark control module just set up like a carbureted truck. The mixture was modified only from input from IAC, TPS and O2.
The timing was whatever the distributor was built around. All the older Howells, AFI and others ran with the stock dizzy. Not the most efficient but it was still
preferable to a carb when you were upside down

 

[SteveH]

I have AFI with AFI's modified FJ62 electronic distributor. In the truck for 4.5 years now.

When I tried to advance the timing a few degrees advanced from the stock setting, the engine ran very poorly - virtually undrivable. I carefully followed AFI's instructions on how to advance the timing. I reset the timing to stock (BB on the pointer) and it ran fine. So, I decided that timing advance (for my 7000' elevation) was not an idea to pursue.

My AFI setup continues to run very well and I have excellent power, but my gas mileage is a dismal 9.5-10.5 at all times. But, I don't care....I just turn the key and go.

 

[lcwizard]

I have AFI with AFI's modified FJ62 electronic distributor. In the truck for 4.5 years now.

When I tried to advance the timing a few degrees advanced from the stock setting, the engine ran very poorly - virtually undrivable. I carefully followed AFI's instructions on how to advance the timing. I reset the timing to stock (BB on the pointer) and it ran fine. So, I decided that timing advance (for my 7000' elevation) was not an idea to pursue.

My AFI setup continues to run very well and I have excellent power, but my gas mileage is a dismal 9.5-10.5 at all times. But, I don't care....I just turn the key and go.

and some wonder why v-8 swaps are popular. I never got less than 12~13 and generally average 15+ with a stock GM 5.7 TBI in both a 55 and 60. I'm in the process of switching the TBI to a Vortec 5.7 that I'll test the Sniper system on. The GM TBI was only putting out a little past 200 hp. The vortec block with Sniper should get over 300.
I'm hoping for at least 12mpg with 35's and 4:88s.

My TBI on the 60, when it had the 2F, always ran about 14 mpgs on the street. It was a hybrid. A 4.3 tbi unit off a van, random ecu off ebay, Howell harness and an adapter from my old stock when I used to build tbi swaps. I ran 4:10s and 33's