Twin Plug 1883 Advance Curve & Ignition System Advice Needed

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Ernesto Cabrera
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#61 Post by Ernesto Cabrera »

45/34 venturi not bad for the rpm you're running. Not sure what the programing capabilities of the 123, but from your post, it seem that you need more advance at the bottom provided you can get to the max advance by 3000 rpm.
 

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GregVandenbussche
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#62 Post by GregVandenbussche »

Hi Ernesto, tried with little more advance (10-12 at 1000rpm) no change, need to try 170 air jets, that's what was working on my 36 with the 1.6
Bt5 Super - used to be fjord green, was painted brass, then brown... sadness

M Penta
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#63 Post by M Penta »

Sounds like some dream engines to me...

Very informative post from the incredibly knowledgeable posters here. I hope that someday I will need to refer to this for an 1883 build.

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GregVandenbussche
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#64 Post by GregVandenbussche »

did 1600 miles in 3 days on it, still have the hesitation on acceleration, something strange though is the hesitation is not present if there is load on the engine, only on acceleration on flat... got a pair of drla 40 that need to be rebuild so working on that now.
Bt5 Super - used to be fjord green, was painted brass, then brown... sadness

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GregVandenbussche
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#65 Post by GregVandenbussche »

by the way, torque is pretty amazing, bring down the rpm overall, and the 5 speed gearbox matted to it are perfect match!
Bt5 Super - used to be fjord green, was painted brass, then brown... sadness

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GregVandenbussche
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#66 Post by GregVandenbussche »

Got some time/mileage on the engine, and switched to 40mm dellortos with 32mm venturi per John W advice since i still couldn't get rid of the hesitation, replaced all ignition wire with 8.5mm one, new cooler spark plug (running 10.5:1 compression) got the car to run pretty well, hesitation moved over 3000 rpm with the use of 9164.1 emulsion tube, 0.3cc per two stroke of accelerator pump. i was going up hill pretty quickly and suddenly the engine started pinging pretty bad, so stopped on the side, car idle good, start right up but will ping really badly under load, checked the following:
- fuel pressure seems good at around 2.5/3 psi
- Checked timing are correct (10 idle, 25@3000)
- replaced fuel filter (was before the pump, so moved the new one by the transmission)
- tested other coils with 0 difference
- ran with and without MSD box, same (maybe a little worst without the MSD)
- checked all wires connection/resistances

I'm starting to think it comes from the 123 ignition module or lower plugs being too cold (denso equivalent to 8 NGK) 123 connect fine so it doesn't really make sense, engine rev freely when the car has no load, will ping/hesitate at any rpm over 2000 with super loud exhaust backfires (gas seems to not burn and end up in hot exhaust), never had a problem on this car that frustrating before :P
Bt5 Super - used to be fjord green, was painted brass, then brown... sadness

philippe VIGNAU
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#67 Post by philippe VIGNAU »

GregVandenbussche wrote:Resurrecting this thread;
Built a 10.5:1 1883, Wilhoit WR68 cam,, running a 123 programmable with twin cap and driving a simple msd with two coils: John advised 10deg static and 26 deg max all in at 3000, however I'm having hesitation around 2500-3000...anyway, trying to figure it out and was wondering if anyone ended up with a specific curve they are happy with?

hi
i am building about same engine ith Wilhoit components 'camshaft, big valves set, scat cran and carillo
i need now an ignition
hat is your experience with one MSD box to feed 2 coils?
some says that losses in volts is oo important , some says that it can cause heat and destroy the MSD...
in other hands others people use 1 box only and it works...
what is your experience about that
thanks philippe

Mark Schumacher
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#68 Post by Mark Schumacher »

Greg
I posted on this thread early on.
Interested in where you got a twin cap/rotor for the programmable 123 distributor
Mark

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GregVandenbussche
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#69 Post by GregVandenbussche »

Hi Philippe, Mark,

Philippe, you can contact me in french if it is easier.

I got the distributor from 123 Ignition Conversion, (not 123ignition alone), it is from netherlands, i have a few feedback after a few month, not really good one:
- first, its pretty expensive, it is basically a added flange on a regular 123ignition bluetooth with one added (wrong) transistor to divide the signal to two "individual" coils. Cap is nissan dual plug cap from 200SX or datsun 510 california.
- The added transistor burned after the first 20min drive using the two coils provided since the way it is wired runs the two coils in parallel anyway creating a 0.6ohm resistance which is too low for that transistor, the car ran better running two bosch blue coils in parallel from the single 123ignition signal once the transistor removed.(running the coils in parallel divide the resistance by 2, two 3ohm coils in parallel = 1.5ohm)
-precision: the distributor rotor angle was off by 20 degree distributor (40 degree crank), too advanced creating the hesitation i was talking about when the car reached the full advance since the spark jumped to the contact for the next cylinder which was closer (from 4 to 1 for example) , i had to modify the rotor mount to get it to run properly.
-I am running the car with one MSD 6AL box running both 1.5ohm coils in parallel, no problems, the spark is way stronger than just a regular 1.5ohm on pertronix on my other engine, the MSD send over 400v to the coils. Regarding people who say it will cause heat, the MSD can run a coil as low as 0.2 ohm, way low, the MSD is not a "smart" component, it can't sense the coils, it just send whatever voltage to whatever coil, two coils in parallel are the same as one, just half the resistance, so in theory half the spark but no side effect for me, box is cold, coil are normal temperature.

To troubleshoot it, i modified a nissan distributor with mechanical advance and inactivated vacuum (since it's reversed), it's a lot of work, but give 25 degree at 3000rpm with 10 static: perfect, except too much advance for the starting, i keep it as a spare for long trips.

Other advice: check your second spark plug seat, sometime they aren't machined all the way through the fins (i had one seat per head that way)

The 1883 with the 5 speed is really fun/comfortable!
Bt5 Super - used to be fjord green, was painted brass, then brown... sadness

Dave Erickson
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#70 Post by Dave Erickson »

GregVandenbussche wrote: ... it is basically a added flange on a regular 123ignition
... Cap is nissan dual plug cap from 200SX or datsun 510 california.
-precision: the distributor rotor angle was off by 20 degree distributor (40 degree crank), too advanced creating the hesitation i was talking about when the car reached the full advance since the spark jumped to the contact for the next cylinder which was closer (from 4 to 1 for example) , i had to modify the rotor mount to get it to run properly.
Greg, it sounds like the added flange was not in the correct position. I've seen a lot of articles on the web about doing this mod to a regular distributor, since building a dual spark engine is a project I plan on undertaking at some point. Wasn't it possible to rotate the flange on the 123 Ignition distributor, rather than modify the rotor mount?

Mark Schumacher
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Re: Twin Plug 1883 Advance Curve & Ignition System Advice Ne

#71 Post by Mark Schumacher »

Thank you for the info on the distributor. Sounds like the product is not fully developed. I remain pleased with my Computronix dual plug set up. Since my post early on this thread I worked with them on the electronics to raise the heat tolerance. I recently completed a weekend of lots of abusive track sessions in high heat with no issues.

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