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Setting ignition advance curves?

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Setting ignition advance curves?

Post #1 by Alastairq » Tue May 15, 2018 10:44 am

Hello. Firstly, I am in the UK, and have a 6-pot, '67 Mustang. A previous owner had replaced the carb, with a Holley-type, single choke unit. I discovered it doesn't have a power control valve [or the threads to screw one in]. The stock distributor is a Load-o-matic [all vacuum advance] type! This set-up worked well enough, but had an enormous static timing figure [I use a strobe, usually]. I have been driving around [trying to make it a daily driver]...with no reliability issues at all. However, I decided to sort things out....options were, buy a replacement, correct,carb....or change the dizzy.
Getting a modern electronic distributor was by far the cheapest option [Being in the UK means I cannot just nip down to the local scrappy for bits] , with a bit of UK owners club forum advice, I bought a TSP 'Street' distributor....the sort with the smaller cap, that needs an external coil., from a US ebay dealer. arrived [Customs duty adds nearly $70 to the price!!] This arrived, and has been successfully fitted, timed, and tested. Story thus far, over.

I reckoned on aiming for around 30 degrees of total advance [ standard engine, small carb] added the 'thin' bush to limit distributor advance to around 17-18 degrees [or so]....with the initial timing around 12 degrees [car is an auto]. I used the middle of the 3 pairs of springs provided....for want of any better advice....this is supposed to give an advance curve similar to that depicted on the graphs provided.
On a ''test'' run last weekend, I found a huge difference when the kickdown was operated [2nd gear]..much better acceleration than before. Top gear 'acceleration' was better than before, but still no better than the average 1300cc Fiesta hatchback would be in top gear!
I now want to look at adjusting the advance curve to improve top gear pulling power...but don't want to lose the 2nd gear power.
Will using the heavy springs [which extend the rate of ignition advance so it's ''all in'' further up the rev range..probably suits a lorry better?] do what I want?
Or, will going to the lighter springs improve things in top gear [torque, rather than BHP?} that the total advance is ''all in'' much earlier in the rev range?
Can I 'mix & match' the springs....say, one light, one play with how the ignition advances?

I am awaiting a 0.7 ohm coil arriving..[currently the car has a 1.5 ohm Pertronix{?} coil] so I can open the plug gaps [currently 35 thou] to something a 4x4 wheel could drop into.
[I have a new set of Autolite plugs huge cost...£35, whatever that is in dollars...but I also have a set of NGKs, at about 1/3rd the cost....are these better? I know Autolite are commonplace in the USA....not so over here........]

To be fair, I haven't found anything conclusive on the net, regarding standard advance curves for the used in the Mustang....which will be vastly different to that used in other vehicles...vans, for example?
Thus....with the choice of springs and bushes , I am relying on what I know [things like, flathead 4 cylinder Fords, for example?} to what combination of springs and bushes would best suit the 200-I6 in the Muzzie.
Long post, I know....sorry.
I expect any answers will be one liners.....but advice is always heeded this end......sadly, money is limited,being retired! [Please bear that in mind when suggesting buying this, that, or the other?]

In addition, I have a 38 DGAS weber carb sitting on the dining room table [no flowers in it!]......that needs to wait until I can either [a] find a cheap, used head on its own, to get a large flat milled on the manifold....or [b] when I pluck up the courage to dismantle a perfectly good usable car! That..can wait....I'm quite a long way away from falling off my perch ....
Thanks folks, in anticipation

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Re: Setting ignition advance curves?

Post #2 by chad » Tue May 15, 2018 1:08 pm

is this an occasional use vehicle, daily driver, racer?
what displacement/yr motor?
which Holley?
auto or manuel transmish?

I do see budget is important (as is mine) other wise I'd say "cam or adj rockers for the future"...

You've read the on-line blurbs on using Mr. Gasket supplies (bending the tab, swaping springs) to their best advantage?
"Big thing is only make one change at a time. Change 2 or more things at a time it becomes difficult to figure which change helped or hurt" turbo2256b » 1/16/2017
Chad - '70 LUEB on '77 frame (i.e. PS, D44, trapezoidal BB 9", 4.11), 250, NV 3550 & DSII to B transplanted, "T" D20/PTO, 2" SL, 1" BL, 4 discs, 33"X15", tool boxes, etc. Seeking: Hydraulic gear motor for Koenig pto. (413) 259-1749

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Re: Setting ignition advance curves?

Post #3 by B RON CO » Tue May 15, 2018 3:42 pm

Hi, to get the most out of your Ford Six Pot plan on getting the Ford Falcon Performance Handbook, highly recommended on this website.
Next, we have a distributor expert here, who can give the best advice concerning the best timing curve. I would use the ported vacuum source on the carb, although some guys like direct vacuum to the distributor. I like the advance to come in as soon as possible. Did you know that you can mix the springs and try one medium and one light? As long as my engine does not knock and ping I will advance the timing a little more.
I like original equipment spark plugs. With the electronic ignition you can open up the gap to .045 thousands. The Pertronix flamethrower coil is a good one, so why not keep it.
Good luck
B RON CO. Still workin' on it!

1933 Ford Pickup - 59A Flathead V8
1966 Ford Bronco - U14 - 170/200 Straight 6
1966 Ford Mustang - 289 V8

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Re: Setting ignition advance curves?

Post #4 by Alastairq » Tue May 15, 2018 4:07 pm

My initial post was obviously too long.....the car shares 'daily driving' duties [limited mileage insurance as a 'classic car'...], so I am aiming for reliability, good fuel consumption, ,yet not letting itself down on the road.
The engine is a 200 I6....standard [stock] aside from the carb, which was probably an exchange replacement at some point in the past 50 years. Gearbox is a C4 auto box...which I am happy with. {I've spent too many decades stirring pudding sticks to not appreciate the auto box}
I don't intend to seriously tune the engine, just get the best I can from it as it is.
The distributor choice was about getting a mechanical advance in the UK, standard Ford distributors are costly via ebay from USA [where, typically, postage costs are as much, if not more than, the price of the goods.]....the TSP item was recommended by another owner...

The car itself was obtained with sensible driving mods...disc front brakes, lowered suspension [which I might raise up a little...stop the rear tyres clouting the wheelarch].......although the standard power steering is far too light for its own good.

Now..if I could achieve over 25 miles per gallon fuel...and be able to overtake stuff without struggling , I'd be happy enough.

[Being left hand drive, in the UK this can be a disadvantage when looking beyond the vehicle in front, for overtaking.]

Hopefully, this distributor will get me some way towards those getting the timing to best suit what the engine needs.

[Bearing in mind, a DUI distributor would set me back nearly $600-plus...import duties, shipping, etc]

Thanks for responding, folks.

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