Igniton req's for turbo apps ?

powerband

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I could use a discussion of ignition and distributor mods for turbo build requirements . Concern is ignition timing:

> there was some discussion of modding (DSII) for restricted advance.

> how does this coordinate with "turbo ignition retard" boxes like MSD-BTM (sic)

http://www.summitracing.com/parts/msd-6462

I understand basic distrib' functions and use DuraSpark with GM HEI trigger on a 250 .

there was some discussion of modding for restricted advance and other mods -

(Falcon Sedan Delivery ; re-curves for turbo app' ?)

thanks
 
Well since you have no responses, I will take a stab at it. The electronic box you posted looks awesome and I was considering this for my turbo build also. These boxes replace the duraspark module altogether so there should be no problems with that. You would run whatever centrifugal advance you would normally run, and the box does the retarding based on your settings via the knob on the dash when boost is detected. The price of this thing ultimately scared me away as I could not find one cheap enough on fleabay. For $400 I would rather try to tune up what I have first as I may get it to work well enough.

I am going to JB weld the advice slots and file them to give the approximate limit I am after. It will take some trial and error I am sure but I have done this before and it is not a big deal. Total cost is basically nothing and if it doesn't work, I am out only time and epoxy and will merely ask my wife for the MSD box for Xmas. Dont be too jealous. I'll get a tie. :cry:
 
Powerband -
I found this site helpful when tinkering with Duraspark distributors - http://www.reincarnation-automotive.com ... index.html

Obviously the above is geared toward N/A applications, not turbo, but it gives the mechanics on how to mod one (with pics, always nice)

The main thing is that generally, under boost, an engine will want less timing to prevent detonation. I'm sure you know this. An easy way to fix this problem is by limiting total timing. In order to keep the base timing at a sane place however, we mod the centrifugal advance to provide less advance.

This is less than ideal. It can provide a safe limit of timing, but it will give us less advance than optimal under certain circumstances (high rpm, low boost). To get more ideal timing for all operating conditions we'd like the full centrifugal advance that our engine would like N/A, but then as boost increases we'd like the timing to be reduced to prevent obvious disaster. This is where the box shines, reducing timing based on boost.

So in the end, I think the answer you were seeking is that you'd run an unmodified distributor (or one modified to match your engine w/o boost) with the box, or mod one for less timing w/o the box. You shouldn't see any difference between the two at max power (assuming the spark is up to the task in both cases) as the timing would be the same at that point, however you might see some drivability improvement or, more likely, a slight efficiency improvement (mpg).

Of course the most optimal ignition is a fully programmable one, but that adds a lot more work.

I hope this answer isn't too elementry for you, and it all makes sense in my head, but it is late for me so I hope I'm not talking gibberish right now ;) If so, I'm sure someone smarter will come along and correct me, g'night
 
I hope this answer isn't too elementry for you, and it all makes sense in my head, but it is late for me so I hope I'm not talking gibberish right now ;) If so, I'm sure someone smarter will come along and correct me, g'night

Speedbug,

that was a concise elementary explanation of basic system requirements that you articulated so I could follow ... , thanks .

interesting - then the "box" will overcome a non-turbo curve NA dist' ? - if that's correct . - I presume a "box" and simple dizzy mods would be most practical. Currently run a mod'd DS I dizzy with GM HEI trigger on a HP 250 , have a few DS II's ,'working block-up turbo build (this winter :chill: )... . "been surfing turbo forums and Mfg' literature,,, and mostly CI ...

have fun

<>
 
interesting - then the "box" will overcome a non-turbo curve NA dist' ?

The box you reference in your link states:

The dash-mounted control knob lets you easily adjust the amount of timing retard from 0-3 degrees per pound of boost pressure

Typically total timing on a NA wedge chamber engine with reasonable compression, cam and octane runs in the low to mid 30 degree range (32-35 degrees total timing). This is further verified when we consider that base timing is usually somewhere between 4 and 12 degrees for this engine and total advance on a 14L slot duraspark distributor is 28 degrees. This gives us a range of 32 to 40 degrees (of course other slot sizes would be a different range.

So, assuming you have a NA total timing of 34 degrees (reasonable with pump gas, tho if you're running low compression and high octane race gas I've seen engine use as much as 42 degrees total timing). Then with the 3 degrees max retard per pound (psi) of boost that the ignition box could give, then at 11.4 psi of boost you could dial the timing all the way back to 0 (TDC). This is ridiculous of course, but I think shows that, yes, the box can overcome a non-turbo curve distributor.

Not trying to sell boxes here, just trying to explain how they work. I'm planning to run mine "locked out" for the time being, while I decide what ignition system I what in the end.
 
Jack:
Cool little switch you posted a link to. Looks like it would give 2 fixed timing reductions at 2 fixed boost pressures (or maybe 3?, that last one isn't plumbed with the others). Is the timing retard built into the wiring pigtail there, or is it computer controlled and those are just the switches themselves?
 
Not trying to sell boxes here, just trying to explain how they work. I'm planning to run mine "locked out" for the time being, while I decide what ignition system I what in the end.

thanks ... not trying to buy boxes, non-ECM timing systems have a few simple variables, mostly mechanical to alter where possible...

"Locked Out" meaning no advance hooked up?

'lots of turbo stuff "NIB" on CL mostly from tuner apps' dreamers, maybe find a "box" ...

have fun
 
My 300 has a TFI distributor, and I'll run it w/o a computer controlling the advance for a while (Megasquirt w/o ignition control). While this is common on drag engines, I've done it on the street quite a bit and works fine as long as you can get enough advance in there and still start it ok. We'll see how this one does.
 
I'll run it w/o a computer controlling the advance for a while
... maybe a human controlling spark advance - like a spark advance control - right on the steering column !

8)


from "The Model A":
On the left side of the steering wheel, move the spark advance lever up to the retard position. The car has no automatic advance.

have fun
 
Yea, that'd be awome, lol! I can just imagine "ooh, its pinging a bit, now which way do I turn this knob? oops"
 
powerband":y5a92x5p said:
I'll run it w/o a computer controlling the advance for a while
... maybe a human controlling spark advance - like a spark advance control - right on the steering column !

8)


from "The Model A":
On the left side of the steering wheel, move the spark advance lever up to the retard position. The car has no automatic advance.

have fun

shouldn't be too hard, replace the vaccum canister with a cable :beer:
 
country fried 6":25uslzgi said:
powerband":25uslzgi said:
I'll run it w/o a computer controlling the advance for a while
... maybe a human controlling spark advance - like a spark advance control - right on the steering column ! 8)
from "The Model A":On the left side of the steering wheel, move the spark advance lever up to the retard position. The car has no automatic advance.
have fun
shouldn't be too hard, replace the vaccum canister with a cable :beer:

NOW, you have my attention.
 
ol' henry already gave you an electronic auto-retard box!

http://www.pirate4x4.com/forum/ford...uraspark-box-third-plug-retards-ignition.html

i've got one in my truck because i figured i'd use it when i get boost set up, but i haven't figured out how it works, if it is discrete or variable, or how to control it.

i have 3 wires on the control plug, and i have read elsewhere it may have something to do with one wire discrete gives you a few degrees advance and the other wire gives you retard, and the third is common.


as far as i can tell, there is no wiring schematic for high elevation or california emission controlled cars this supposedly came on.

the word i heard was that it was on emission control cars that had EGR and were way advanced from factory, so when you hit a load and EGR shut off (low mani vac) the ignition would compensate by pulling timing. leads me to believe it was a discrete pressure switch.

same thing may have been true for cars that were lean/advanced at high altitude to run good, the box retarded them so when they came down the mountain they wouldn't blow up.


either way, i'll be doing some research with this very soon, hoping i can hook to a pressure switch (variable would be awesome with a transducer) and get an automagic boost retard.





if that doesn't work, i'm looking at a microcontroller (digital) system that might do the same thing, kinda like E-dis but cheaper.
 
motzingg":31uex7tm said:
ol' henry already gave you an electronic auto-retard box!

http://www.pirate4x4.com/forum/ford...uraspark-box-third-plug-retards-ignition.html

i've got one in my truck because i figured i'd use it when i get boost set up, but i haven't figured out how it works, if it is discrete or variable, or how to control it. ither way, i'll be doing some research with this very soon, hoping i can hook to a pressure switch (variable would be awesome with a transducer) and get an automagic boost retard.
if that doesn't work, i'm looking at a microcontroller (digital) system that might do the same thing, kinda like E-dis but cheaper.
I'll be watching, I have one of those.
 
Collardo member Mark P has long been relegated to Guest in the member list, and is no longer here to elaborate, nor can his posts be searched. He was ex Ford, and might be at the Honda forums now, but he had some interesting info on some 2-bbl Fox engines, and a lot on the Duraspark II yellow grommet. Before 1981, it was possible to have an engine FMV complianced without an VIN code change, like the A code 2.3 could be carb or carby turbo, with just a subcode required. Ford got hammered by the EPA before the Fox Mustang Maclaren M81 came out, because under the 6 to 8 psi boost conditions on the variable boost screw, the 2.3 carb turbo wasn't tested for emissions compliance, and so the whole package had to be withdrawn. The 2.3 Turbo used a yellow grommet Motorcraft spark amplifier, and it worked really well. Its just that 9.5:1 compression, long exhast turbo lag and flimsy rods and cracking turbo and intake manifolds weren't conducive to owner happiness. Without the yellow grommet DSII ignition, the 2.3 Turbo would have died even earlier...

And it was proposed a 2-bbl carb package could be sold for Police Interceptor or Collage Security work. So lots of little changes could be made without the whole CARB process being invoked. Back then, a yellow or blue grommet Durapsark II was nothing. These days, it depends on if your in CO or CA, the worst states for being pinged by the smog nazis before an IM test.

It was said that when Fords EECIII first came out in late 1979, the Lincoln 131 HP 302 had a brown grommet fully controlled ignition system which had electronic feed in like the latter sequential injected and waste spark engines. They mapped tdc and firing electronically with a semi conventional distributor. A lot like the Nissan RB20e/24e/26e/30e ECCS engines. The distributor was just a simple switch with total control to the wires by the DSIII and EECIII.

Two out of the six Ford US Durasparks had that ignition advance retard feature.

Namely, the brown grommet Duraspark 3 and yellow grommet Duraspark 2.

They were a step up on the Green, Red and Puce Duraspark I and the blue grommet Duraspark II because they had an absolute pressure sensor in them which allowed better cold starts and limited advance under certain conditions.

The yellow grommet DSII is an easy and cool on-the-sly change which also yields good results on turbo engines. The brown grommet Duraspark III, well... people are still tying to be understand it today...rocket scientists are well known to reduce total amounts of steps by cutting out previous step wise conventions, like running integrations and logarithmic lookups, and having ex NASA engineers like Chuck Misler made those part electronic and part pneumatic fault logging systems work well, but they were massively hard to fathom. The Duraspark III and Brown grommet EEC III 5.0CFI and Variable Venturi 7200 2-bbl carb engines came out, it employed a very complicated system, and when the 3.8, 5.0 got updated to CFI, the EECII and Duraspark III conventions were skipped and EECIV got TFI ingition
 
wow... xstacy as usual a post full of crazy information in a fantastic stream of concious format.

It took me a couple readings to parse, but it sounds like it is pretty do-able.

my biggest problem right now is the lack of a timing mark on my engine and the lack of a fan shroud, both of which have discouraged me from dicking around with the system.


the bugger of it is just finding a wiring schematic for the yellow grommet car/truck... should be easy to come by but so far i haven't found any mention of it anywhere. Perhaps it was an addendum that got handed out to dealers to put in their 3-ring factory manuals and never made the transition to Clymer or the commonly available bound manual that is more common?

do you recollect if the switch is discrete or preportional? There are 3 wires so i had assumed there were either 2 switches or a dual stage switch. Some of those old pressure transducers require an excitation voltage along with a common and a signal wire, but that seems odd. worst case i just start tying wires together and watch where the timing goes... if the box fries they are only 10 bucks from rock auto.. i should probably have a spare anyhow.
 
this is good, looks like its a ford doc. mentions the 'pressure switch' directly

http://www.maverickcomet.com/Repair/RepairInfo/1975_1979DuraSpark.pdf

elsewhere, someone says 2 deg and 4 deg specifically, which would make sense if it is doing 3 wires and 1 supply, 2 signal return wires depending on position of the switch.

i can't tell for sure, but it looks like the switch mounts to the cover of the box. since the box cover isn't grounded, that means that the switch would be floating ground. the switch also looks like it is plastic, just from the drawings... therefore you'd need supply and 1 return for each 'mode' meaning that one of the 3 wires might be hot and two might be return wires.

This link is the diagram and writeup i had seen initially. Clearly implies that it is discrete 1 or 2 mode. Hopefully that is true because it will be easy to hack.
http://www.ford-trucks.com/user_gallery/displayimage.php?&photoid=5952&width=0
for the life of me i cant find that barometric pressure switch for sale anywhere. now that i'm looking for it i can't find the dual mode box either, i bought mine off of rock auto on clearance, maybe they sold them out and now they're gone...
 
also depending on the application they talk about 'vacuum switch for economy/emissions' perhaps they had it wired up so it was in the 'middle' position and instead of -2, -4 deg it could go +2/-2 deg
 
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