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Author: Subject: Pinto Ignition advance curve
simonrh

posted on 20/8/14 at 12:55 PM Reply With Quote
Pinto Ignition advance curve

I have a quantum xtreme running a 2.0 pinto that I got a few suggestions from people on here before about sorting a few cooling issues before. Most are now cured but a few still remain.

One of my concerns was that it is running too much advance.

Distributor is electronic with one of these amplifiers:



It runs no vacuum advance because it has twin weber 45s.

The other day I checked the advance at idle and it was 17 degrees so i knocked it back to 12 as this seemed to be more in keeping with suggestions as to where they are supposed to be on a mild engine.

Checked the advance at 3000, 3500, 4000 revs today (at work where noise is less of an issue) and it only advanced to 27 degrees. Should really be more like 34 ish as far as i can see for a mildly tweaked pinto.

So the question is, before I get into twiddlling with springs and stops inside dizzy:
Is all the advance controlled from within the centrifugal advance on this distributor when you use this ignition system (i.e. the electronics don't control any of it).?

Is it going to hurt my cooling running a load more of advance at idle in order to get the timing right when my the revs are up.

Are the numbers I am using about right for twin 45s, mild cam big shiny 4-1 exhaust.

Thanks in advance

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Andy S

posted on 20/8/14 at 01:38 PM Reply With Quote
I take it that the dizzy has the vac advance module but its just not connected.

If it is that is the system I have on an old Pinto - first off if you are not using the vac advance then lock the advance plate in the dizzy so there is no chance of it floating about.

Put the 850 RPM advance back to 17-18 degress - the idle advance is sod all to do with engine tune. Your primary goal is to get the timing right for maximum torque. so you want the 34+ degrees back to where it should be at 3000 RPM.

The dizzy should be set for your maximum advance requirement first and for start / idle second. example if you set at 34/36 maximum and you cannot get it to start because there is too much advance at cranking then only knock it back as far as needed to get it to start.

Best bet is to modify the dizzy but I would have thought it should have at least 20 degrees of crank advance minimum so 14/16 static should give your 34/36 all in at 3000.

[Edited on 20/8/14 by Andy S]





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mookaloid

posted on 20/8/14 at 01:42 PM Reply With Quote
You will know if it running too much advance because it will start pinking under load.

If you have never heard pinking it sounds like you have left a couple of spanners in the rocker cover ....

you should advance the ignition until you hear the pinking then back it off until you don't. It will be about right then.

it will run hotter if it is too retarded by the way.





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snapper

posted on 20/8/14 at 02:21 PM Reply With Quote
Pinto max advance is more like 36 degrees @ 3600 although this can vary between 34 & 38 at 3400 to 3800
If you were running 38 @ 3800 I suppose 30 @ 3000 would be ok
For safety start with 34@3600 and see how it goes
Megajolt is the next thing to consider





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mcerd1

posted on 20/8/14 at 02:36 PM Reply With Quote
if you know the dizzy is in good working order then you could just connect up the vac. advance

you'll need to take a vac line from all 4 cylinders - join these into a small chamber to balance out the pulses and take a line from this to the dizzy.

quote:
Originally posted by simonrh
So the question is, before I get into twiddlling with springs and stops inside dizzy:
Is all the advance controlled from within the centrifugal advance on this distributor when you use this ignition system (i.e. the electronics don't control any of it).?
I could be wrong but I thought the system you have was a mechanical advance with just the points replaced by the electronics




as above you could get a modified dizzy with the vac advance removed properly - but the issue with this (and you current setup) is even when they are tuned right they are only a 2D system, which means you fuel economy will suffer badly (mind you the webers are bad enough on there own....) also the throttle response, power and torque could all suffer or be compromised at certain parts of the rev range


if you went to a 3D system like megajolt you'll need to add a TPS to the carbs or a map sensor (connected to all 4 cylinders the same way as the vac advance - but a TPS is a bit easier to get right)
these setups let you tune the ignition however you like without the big compromises of the mechanical / semi-mechanical setups
but you do need to keep the bottom part of the dizzy on a pinto as it drives the oil pump !



[Edited on 20/8/2014 by mcerd1]





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simonrh

posted on 20/8/14 at 02:42 PM Reply With Quote
Thanks for all the comments, appreciated.

I am going to swing the idle timing back forward to 18 degrees tonight (because I can't do 4000 rpm without p1ssing off the neighbours).

I will have a look a tlocking of the vac advance so it isn't scattering the timing about. It has just been capped off on the diaphragm for now.

And then re-check the full advance next time I am at work again.

I have a nice digital light so overall will aim for 35 degrees at full chat and see if it will support that at part throttle and lower revs.

If it wont then it is meddling with distributor / modified ditributor or programmable

I like the look of the no-diz system as an alternative to a mega jolt.

I just need to decide if my long term goal isn't to go to throttle bodies before I buy an ignition only kit

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JeffHs

posted on 20/8/14 at 05:18 PM Reply With Quote
I'm running a non-vac dizzy and twin 40s on a pinto. Timing is set to 36 degrees . Starting is a bit odd because you can tell it's way more advanced than a normal setup. Sometimes it seems to stumble when cranking, but it always goes eventually and then it's just fine.
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Andy S

posted on 20/8/14 at 05:45 PM Reply With Quote
Just make sure you don't seal off vac pot - air expands and contracts with temperature - better if not used to remove it blank off the slot and then screw the plates together.

Vac is just a part throttle economy/emissions device anyway so of little consequence in an occasional blast toy.





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BaileyPerformance

posted on 20/8/14 at 06:28 PM Reply With Quote
Tuned Pintos love a quick advance curve, as stated the maximum total timing should not exceed 36deg.

The total timing is the maximum timing seen, the way to check it is rev the engine until no more advance is given. Depending on the camshaft used the total timing should be all in 3500-4000rpm, no more advance after that.

Don't set it at 36deg at a particular RPM unless you have checked at high RPM as you mite end up with 40deg at 5000RPM!

After the timing has been set, let the engine idle and note the idle timing, if between 12-16deg - great, much more than that the starter may struggle to crank the engine as it may kick back.

Getting the advance curve spot on is a lot of work as it involves spring changes as maybe bob weight stops to limit the maximum advance at high RPM.

Much quicker to fit Megajolt!

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Dingz

posted on 20/8/14 at 08:53 PM Reply With Quote
You may find this interesting if you wish to know more, Dizzy





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britishtrident

posted on 21/8/14 at 11:50 AM Reply With Quote
Before doing else anything make sure the centrifugal mechanism is free and has just a touch of lubrication.

As distributors wear and the springs stretch the advance curve tends to become steeper at low RPM so maximum centrafugal advance is reached at too low an RPM. The resulting excessive mid range ignition advance can cause pinking as the revs pass through the medium RPM band under load.

Pinking is audible as the jingling tinkling sound already described the best test for is to listen to the (fully warmed up) engine as it accelerates underload from about 1300 rpm to 2500 rpm in 3rd, 4th or 5th gear with a wide open throttle..

One other thing to do is check the ignition timing of both #1 and #4 cylinders as any major variation in ignition timing between the two is a sign of a worn or bent distributor.

[Edited on 21/8/14 by britishtrident]





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simonrh

posted on 21/8/14 at 01:03 PM Reply With Quote
Thanks all, looks like a weekend spent with a timing light
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Paul Turner

posted on 21/8/14 at 02:11 PM Reply With Quote
This is based on my X-Flow experience but since both engines were clockwork and Fords the same should apply.

The max advance with a standard distributor was achieved through a combination of vacuum and centrifugal. Take off the vacuum pipe and you will never get full advance.

After market distributors were modified to enable the centrifugal advance to deal with the total advance required with the correct advance at other revs/loads. As with all these clockwork systems it was a compromise but a compromise that worked pretty well. I ran a X-Flow on 40's/45's for 10 years with a modified Fiesta Bosch distributor (no vacuum) and I got the required 34 degrees at about 4000 rpm with 12 degrees at idle. Tried an Aldon once briefly, very briefly, was told they were brilliant. To get 34 degrees at 4000 rpm you had to set it with 16 degrees at idle, bloody thing would hardly turn over. Set it at 12 degrees to get it started and it had no power, totally useless. Fortunately the supplier agreed it was tat, sent it back and did not charge for the RR time.

So has your distributor been modified (preferably by someone who knows what they are doing and not Aldon) or is it bog standard.

After 10 years with the clockwork system I did a deal with a supplier to fit Weber Alpha 3D ignition. At the time there were no fitting kits or maps available for the X-Flow and the supplier wanted to provide an off the shelf solution. He used my car as a guinea pig and made the brackets, fitted the timing disc, fitted the TP and mapped it, all free, I only paid for the basic kit. It made quite a difference to the car, much more flexible, much more economical (went from 16 mpg to 22 mpg) but the max power only increased from 172 to 172.5 flywheel bhp (he did a run before as a control).

Would I recommend the upgrade to mapped 3D ignition, well yes but don't do it to save money immediately. At todays pump prices it would take 2 years to break even doing 2000 miles a year, back in the late 90's with cheaper fuel it was probably nearer 4 years.

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Chris_Xtreme

posted on 21/8/14 at 09:51 PM Reply With Quote
atspeed on my xtreme with the same setup ,just popped open the plate on the side of the standard ford dizzy and pushed the weights a bit... he said it was just an experienced adjustment. however he managed to get the advance curve spot on.

I think this is what you need to do to sort it.. I didn't have the vacuum connected as I too had twin 40s. It was this adjustment that sorted my running hot.

good luck.

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haz87

posted on 22/8/14 at 08:49 AM Reply With Quote
quote:
Originally posted by Paul Turner
The max advance with a standard distributor was achieved through a combination of vacuum and centrifugal. Take off the vacuum pipe and you will never get full advance.



Yes you will. Max advance is measured at the point where vacuum is as good as null and void (say 5k for arguments sake knowing vac definitly won't be apparent at these rpm)

However, the HIGHEST advance point won't be achieved without a combination of vacuum and centrifugal. Though this is not max advance when talking about timing curves.

(bit of a pedantic point I know so hope its not taken the wrong way)

[Edited on 22/8/14 by haz87]

[Edited on 22/8/14 by haz87]

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simonrh

posted on 25/8/14 at 05:23 PM Reply With Quote
Swung idle timing forward a few degrees at a time, drove to check for pinking and repeated. I have now got pushing 20 degrees idle advance. This should give me about 35 degrees max which I will check.
Engine turns over OK still will need to double check when it is cold

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