CARBURETION and your Large/Small port 16V 4AG
02-16-2007, 09:17 PM
Post: #1
CARBURETION and your Large/Small port 16V 4AG
IGNITION OPTIONS FOR CARBED 4AGE ENTHUSIASTS

I saw that there is still quite a bit of a hurdle in getting proper spark & timing in carbed 4AGE's so I thought I'd add some info directly related to this area of interest.

1. Use the stock blue top 4AGE distributor locked out at the timing of your choosing.
2. Use the stock blue top 4AGE distributor w/ the MSD 6A/L w/ MSD p/n 8980/8981 timing curve "computer" - to use the stock tach you will need to use MSD's p/n 8920 tach/fuel adapter NOT the 8910EIS (fuel injected w/ 6AL) or 8910. the 8920 is for the magnetic pick-up leads that are used from the Blue Top Distributor. If using an aftermarket Tach then the 8920 is not necessary.


note* - the 8980 is a fixed timing curve. this means you would set your distributor timing at your intended idle timing. the 8980 will advance your timing and max out at 20 degrees full advance e.g. if your idle is set at 10 degrees just under 1k your full advance will be 30 at 3k.

note** - the 8981 is a "programmable" timing curve unit. it's still based on the same design of the 8980 BUT you get to dictate when timing advance starts and ends in your rpm range.


3. Use the 4K distributor from a starlet. It will need to be adapted to mount up to the 4AGE head. You will also need the gear from a 4AGE distributor to replace the 4K's in order for it to spin off of the 4AGE exhaust cam.
4. IDS w/ megasquirt and crank tooth wheel and sensor. electromotive and other companies can provide you with good IDS setups.


other suggestions are welcome. i added this post in order to facilitate searches for other members who are interested.

originally posted on Club4ag.com
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02-16-2007, 09:26 PM
Post: #2
CARBURETION and your Large/Small port 16V 4AG
CARBED 4AGE GROCERY LIST ESSENTIALS

This is not an exhaustive list in that I will not include ALL the options for specific components as then that would then nullify this post as being entitled "essentials". I leave the customizations to the individual(s)

1. Carb(s): dual sidedraughts, dual down draughts, single down draft 4 barrel/ 2 barrel
2. Intake Manifold for mounting your carb(s) of choice to the 4AGE head
3. HVLP (high-volume low-pressure) Electric Fuel Pump:

Webers - no more than 4 lbs of delivery
Mikuni's no more than 3.5 lbs of delivery
recommendations: carter 4070 or holley's red low pressure electric fuel pump
i highly advise against a mechanical fuel pump

4. Adjustable Low Pressure FPR (fuel pressure regulator) and FP Gauge (liquid filled, low increment recommended)
5. Throttle Linkage
6. Appropriate means of plugging the fuel injector ports (e.g. freeze plugs, injector port plugs from tweakit
- i recommend using the fuel injector port on no.4 for your vacuum assited brake booster if your manifold doesn't have an available vacuum port. you can also tap it and outfit it w/ a barbed brass fitting. you decide
7. Corrective Fuel & Air Jets or a vendor that you can easily obtain them from
8. For spark please see above in the "IGNITION OPTIONS FOR CARBED 4AGE ENTHUSIASTS" post.


originally posted on Club4ag.com

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02-16-2007, 10:07 PM
Post: #3
CARBURETION and your Large/Small port 16V 4AG
dr.occa Wrote:[b]3. Use the 4K distributor from a starlet. It will need to be adapted to mount up to the 4AGE head. You will also need the gear from a 4AGE distributor to replace the 4K's in order for it to spin off of the 4AGE exhaust cam.

you have a how to for this?

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02-16-2007, 10:09 PM
Post: #4
CARBURETION and your Large/Small port 16V 4AG
1. sidedraughts
2. options are ready
3. what about Facet ?
4. not obligatory
5. important !
6. all ports in one "buffer" rail for good vac. signal. This allows use of MAP (vac) based iginition too (like stock MAP ECU).
7. Delorto & Weber have wide support
8. simple copper-electrode sparks will work, better change them often

Add to the 1-st posting:
5. MjLj Evil
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02-17-2007, 12:21 AM
Post: #5
CARBURETION and your Large/Small port 16V 4AG
AEsuperG Wrote:
dr.occa Wrote:[b]3. Use the 4K distributor from a starlet. It will need to be adapted to mount up to the 4AGE head. You will also need the gear from a 4AGE distributor to replace the 4K's in order for it to spin off of the 4AGE exhaust cam.

you have a how to for this?

you can either see about securing one from Japan, have a machine shop fab one up for you or DIY. here are some pics to give you an idea:

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[Image: AEU86 AE86 - CARBURETION and your Large/...rt 16V 4AG]
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02-17-2007, 12:50 AM
Post: #6
CARBURETION and your Large/Small port 16V 4AG
jamiemirror Wrote:...
4. not obligatory
...

i disagree. what sort of fuel pump do you plan on using? unless you've come across an electric fuel pump that consistently gives 4 to 4.5lbs of pressure un-regulated (and if you have, please provide the brand and
part number if you would be so kind Wink) the FPR is obligatory.

jamiemirror Wrote:6. all ports in one "buffer" rail for good vac. signal. This allows use of MAP (vac) based iginition too (like stock MAP ECU)...
this is overkill on vacuum for brake booster assisted braking. why would you attempt to use the efi ECU for anything when it will not properly manage the system any longer? what vacuum sensors will you be continuing to use? this doesn't make any sense. the single throttle body will be gone among other needed vacuum lines and sensors for the ecu to give proper timing & fuel management. when the ecu is no longer receiving important data from sensors it will retard timing if anything. the engine will not run properly w/o the data it's looking for.

Basically, once you've converted the 4AGE to carburetion, the ECU is just dead wait for you. The car no longer needs it.

jamiemirror Wrote:...8. simple copper-electrode sparks will work, better change them often...
so, how do you provide the necessary timing curve w/ said ignition? granted, here in the states an HEI ignition module (used by 90's model Chevy Novas) from a local auto-parts store ($16 USD) will do the trick but no timing curve.

jamiemirror Wrote:...Add to the 1-st posting:
5. MjLj Evil
ummmm, what is that?
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02-17-2007, 02:54 PM
Post: #7
CARBURETION and your Large/Small port 16V 4AG
You can still use the Stock ECU to control timing if you continue to provide it with a semi stable map and TPS signal, its not redundant.

If not, why bother with all this hard work for sorting a crap ignition curve when you cna just buy an ignition only management system?
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02-17-2007, 05:32 PM
Post: #8
CARBURETION and your Large/Small port 16V 4AG
BenR Wrote:You can still use the Stock ECU to control timing if you continue to provide it with a semi stable map and TPS signal, its not redundant.

If not, why bother with all this hard work for sorting a crap ignition curve when you cna just buy an ignition only management system?

And it wouldn't be more work to rig up a "semi stable map" signal along w/ jury rigging the TPS just to be able to use the efi ECU (which you won't be able to manipulate w/o extra work and extra money)? I'm not arguing that it isn't do-able. Anything can be rigged up. The information provided above is to facilitate not to convolute the process in converting to a carbureted platform. What I've outlined above is straight forward.

As for a "crap ignition curve" I would ask, how would it be "crap"? I guess it would be schite if compared to let's say a mega-jolt, haltech, electromotive, etc...stand alone system. But I would argue that they all would produce a turds worth of timing in unskilled hands and conversely. Maybe then, our japanese counter parts using the archaic kp distributor adapted to the 4AG haven't a clue that they're using "crap" to achieve only a "crap ignition curve".

Do this, go through what's been outlined above and show where failure would occur in the process drawn out. If there's an even quicker, affordable(a method accessible to all that wouldn't necessitate illegal activity) and easier option w/ an =/> effect produced then by-all-means please share.
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02-17-2007, 08:31 PM
Post: #9
CARBURETION and your Large/Small port 16V 4AG
dr.occa, MjLj=MegaJolt. Ignition only management "box". Fully mappable, needs MAP or TPS signal. Can be bought as kit or assembled device.
When you go ITB style - you can't use AFM (vane flap-based device). Using TPS, static advance or advance based on RPM only is practical mostly for circuit racing. So you can try to deliver good vac. signal to MAP sensor and use MAP/RPM igniotion maps (this is the MegaJolt task).
About fuel pumps - any carburated Honda or Subaru is good donor (for 2-nd hand pumps) but FACET brand pumps are available new too. Choose one having in mind your maximum power (and fuel consumption).
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02-17-2007, 11:56 PM
Post: #10
CARBURETION and your Large/Small port 16V 4AG
dr.occa Wrote:
jamiemirror Wrote:...
4. not obligatory
...

i disagree. what sort of fuel pump do you plan on using? unless you've come across an electric fuel pump that consistently gives 4 to 4.5lbs of pressure un-regulated (and if you have, please provide the brand and
part number if you would be so kind Wink) the FPR is obligatory.

Sorry, forgot the link:
http://stores.ebay.com/SU-AUTOPART_FUEL-...idZ2QQtZkm
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