Wideband Results

[King_vw61]

stop adjusting your pump to cover up another problem.

You are lean on main jets

read what I wrote. Drive it without using the pump jet, very slow on the pedal so it does not squirt at all. IT is only for when you stab the gas to compensate for all the air coming into the engine. thats it.
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1961 Ragtop, Autocraft 2783cc for street/strip 10k miles and counting...230.84 HP to the wheels thru Muffler 13.4 to 1 on E85
https://www.instagram.com/king_vw61/?hl=en

[boxer74]

[VdanielW]

[boxer74]

[NJ John]

Anyone use a Autometer a/f gauge? Thinking about buying one. Just over $200 on Amazon with no bad reviews. AEM gets trashed on Amazon.
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1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[King_vw61]

Autometer owns innovate and they have been doing afr and data logging for a while. When I send in my Lm2 it goes to Autometer and comes back in one of their boxes. Good service.
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1961 Ragtop, Autocraft 2783cc for street/strip 10k miles and counting...230.84 HP to the wheels thru Muffler 13.4 to 1 on E85
https://www.instagram.com/king_vw61/?hl=en

[Zed999]

[MikeyM73]

Hey guys,

After reading through all of this over eons, I think things may have just fully "clicked". Please correct me if I misspeak - the air corrector jets control the timing of when the main circuit starts to add fuel in the overall delivery as the carbs are transitioning from idle to main, through the Progression circuit. Is that correct?

In reading Johns (AC) posts over the years (and way early on in this one), I recall him saying to start with the largest jet you have then increase air corrector jet size until transition is smooth, then down jet the mains until you get a good reading or, for those who don't have an AF meter, lean pop/miss then upjet until you get good plug readings and CHTs.

Is that about right from a rough perspective? If so, it becomes completely logical to me why different weight vehicles with similar setups would need to have completely different jetting - this I already knew based on the basics but just solidifies it since mains would have to come in a little earlier to move a heavier vehicle.

Thanks,
Mikey
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'73 Pop-top Westy, found sitting in a field for 10+ years, cleaned up, rebuilt furniture, reloved. Original 1.7 block/fully polished crank, 93mm 1.8L balanced AA pistons & cylinders, new 1.8L balanced rods, HAM 42/36 heads, Scat C25 cam & lubalobe lifters, Dual HPMX40s, R2C filters w/ Outerwears pre-filters, functioning thermostat & flaps, Pertronix Flamethrower III, 4-1 exhaust w/ Cherry Bomb 2" turbo muffler & OEM heater boxes, averages about 19-22ish on the highway.

[boxer74]

[MikeyM73]

Man, that's awesome. Thanks very much.

For the longest time i, too, like the OP have been chasing a very small flat spot through the progression circuit. Clatter's offered to help but I haven't been able to make it down to his place yet. I've gone through many variations of idle and main jets, air correctors from 170 all the way to 210s and was, to be honest, a bit concerned to go any more just due to leaning out the mains. But every time I've gone up on AC jets, it gets better and better.

I'm currently running 135 mains, 210 airs with 28 vents, 52 idles ( I think I need to go to 50s or a hair below), timing is 10* @ idle, 28 all in with a Pertronix FF3. Plug readings look good so far, CHTs are in check, vacuum advance is capped and I'm hard-set to 28* full mechanical because I can't pull much ported vacuum with this C25. Still, performance and drivability are very good, mileage is about 18-22ish on the highway depending on driving conditions. I bet if I go with 215 or 220 airs that would get me just about perfect. If it leans out those 135s a hair on the freeway, I bet I'd probably get a bit better mileage and, according to what I've read here, cooler temps. We'll give it a shot and see what happens.

Thanks again, great thread.

Mikey.
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'73 Pop-top Westy, found sitting in a field for 10+ years, cleaned up, rebuilt furniture, reloved. Original 1.7 block/fully polished crank, 93mm 1.8L balanced AA pistons & cylinders, new 1.8L balanced rods, HAM 42/36 heads, Scat C25 cam & lubalobe lifters, Dual HPMX40s, R2C filters w/ Outerwears pre-filters, functioning thermostat & flaps, Pertronix Flamethrower III, 4-1 exhaust w/ Cherry Bomb 2" turbo muffler & OEM heater boxes, averages about 19-22ish on the highway.

[King_vw61]

I'm finding that on E85 it's a bit tricky. I went down on air to bring the mains in sooner. I had 210, 205, 200's and always had issues cruising on the freeway. was always 9 afr.

I went to 180 airs and it is bringing in the mains sooner, I now run a 205 main with 180 airs. It has never ran better.

The afr is closer to 11 and for me that's good.I have little to no port velocity at low Rpm's

2783cc on E85 (30 to 35% more fuel, but its 106 octane)
51.5 Ida's
78 idles with 110 holders
205 mains
180 airs
70 pump jets
5.0 aux vents
48 vents
13.4 to 1


Idle at 30 degree then at 1300 drops to 18 to start the curve up to 31 total.(MSD Power grid)
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1961 Ragtop, Autocraft 2783cc for street/strip 10k miles and counting...230.84 HP to the wheels thru Muffler 13.4 to 1 on E85
https://www.instagram.com/king_vw61/?hl=en

[MikeyM73]

Dann dude, your motor is a FAR cry from mine! On the WAY more badass side. Would love to have something like that in my bus detuned a bit for the weight factor but still. But same principal on the carbs, right? Where are you finding the 1/2 size jets? I normally go through Pierce Manifolds out of Gilroy CA and they only list the full steps.

Thanks,
Mikey
_________________
'73 Pop-top Westy, found sitting in a field for 10+ years, cleaned up, rebuilt furniture, reloved. Original 1.7 block/fully polished crank, 93mm 1.8L balanced AA pistons & cylinders, new 1.8L balanced rods, HAM 42/36 heads, Scat C25 cam & lubalobe lifters, Dual HPMX40s, R2C filters w/ Outerwears pre-filters, functioning thermostat & flaps, Pertronix Flamethrower III, 4-1 exhaust w/ Cherry Bomb 2" turbo muffler & OEM heater boxes, averages about 19-22ish on the highway.

[King_vw61]

I ream them and use pin gauges to make sure they are all the same.
_________________
1961 Ragtop, Autocraft 2783cc for street/strip 10k miles and counting...230.84 HP to the wheels thru Muffler 13.4 to 1 on E85
https://www.instagram.com/king_vw61/?hl=en

[MikeyM73]

Ahh.. I have none of that but who knows.. maybe in time .

Thanks,
Mikey
_________________
'73 Pop-top Westy, found sitting in a field for 10+ years, cleaned up, rebuilt furniture, reloved. Original 1.7 block/fully polished crank, 93mm 1.8L balanced AA pistons & cylinders, new 1.8L balanced rods, HAM 42/36 heads, Scat C25 cam & lubalobe lifters, Dual HPMX40s, R2C filters w/ Outerwears pre-filters, functioning thermostat & flaps, Pertronix Flamethrower III, 4-1 exhaust w/ Cherry Bomb 2" turbo muffler & OEM heater boxes, averages about 19-22ish on the highway.

[boxer74]

I have a question about tuning for lean cruise. I currently have only a CB Magnaspark II mechanical advance distributor. I realize this will limit me to around 13:1 and no benefit to MPG from tuning for lean cruise. My idles are 47.5.

If I were to lock out my distributor and add the CB Black Box which includes manifold vacuum advance, would I run leaner at cruise in progression simply due to the additional advance, or would I have to jet further lean on the idle jet?
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74 Super
84 Westy

[jimmyhoffa]

You would almost certainly need to back down the idle jet sizing a tad. I tried that route, EXACTLY like you describe. I had a Magnaspark without a black box, with 12.5:1 or 13:1 jetting everywhere. I got a black box, and played with a combination of idle jet sizing, float height, and air corrector jet sizing to get the transition into and out of lean cruise just how I wanted it. Both worked, but I settled back on centrifugal distributor and "standard" jetting since it's an off-road car.

I also did the exact same experiment with my Mexican EFI engine running MicroSquirt. Same results, just easier because you type your jetting into a spreadsheet and press 'SEND' with the engine still running. Lean cruise really can be a nice cool burn with the timing right and essentially as little fuel as will maintain combustion. Good luck!
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1974 Chenowth 2RL #1244 Street Legal
My other car isn't ridiculous.

[Lingwendil]

[boxer74]

[boxer74]

[sled]