Ignition Timing Ford 347

[Ian Bissett]

Hi all,

My Ford 347 with Weber IDFs has been playing up of late and two starter motors have failed within a month. Both occasions, it happened after priming the engine too much (maybe pumping the accelerator pedal too much before ignition; 4 times!), with what appeared to be a backfire through the Weber trumpets. On investigation, on both occasions one of the small starter motor inner gears had sheared in half suggesting possible back rotation of the flywheel (and thus cylinder) during start; too advance timing perhaps?

I spoke with Frank Catt a few days ago and he has given me some sage advise for things to check, many thanks for that Frank.

Wrt ignition timing on idle, I have seen BTDC numbers varying from 6° to 15°, and obviously this will make a difference. On 3000rpm, there seems to be reasonable consistency in that it should be around 32-34° BTDC.

Can anyone advise what the BTDC should be on 1000 rpm idle?

Many thanks
Ian

 

[Jac Mac]

On the limited info you have given.. the fact your timing is not constant at idle suggests that the mech advance weight springs are weak which allows the variation from 6°/15°, if your 32°/34° timing is stable from 3000 thru 5000 ( although if its MSD you should see a slight retard at the upper end) you can rule out play in the timing chain. You should also closely inspect the cap & rotor for any tracking, or cracks.
Would help to know more about your motor specs, cam, comp, heads, ignition system..

 

[Ian Bissett]

Sorry, I didn't articulate my question very well! What I meant was, what would be a typically acceptable BTDC at idle? I haven't yet looked at tmy ignition timing but plan to, and I have seen different recommendations from different sources, one suggesting 6deg is ok, and one suggesting 15deg is ok.

When I do check my timing, it will be adjusted to ensure around 32-34deg at >3000rpm, but what could I reasonably expect to accept at around 1000rpm idle, 6, or 15 or something else?

Unfortunately, I can't advise on cam, comp heads etc as I simply don't know. Huddart engines supplied the engine and at the time I didn't ask the question, and it wasn't written down in any documentation.

Thanks
Ian

 

[Jac Mac]

Why dont you give Mike? Huddart a call then, he used to post here a lot and seemed to know his stuff.
If you set it at ~32°@ 3000 you will get an initial number of whatever the dizzy has got built into it and the weights / springs would need to be changed to alter that.
Some folk think webers need more total timing than similar 4bbl engines, that depends a lot more on the rest of the engine build and how you use/drive the car. If it was a 4bbl race car I would use about 14° initial and a total of 32°/34°, but that may not suit your application, plus given the problem has only recently occurred you should allow for the possibilty of other problems being the cause. Call Mike, he should recall your particular engine.

 

[Bill Musarra]

One thing you left out. What ECU are you using, or are you.If so then you may have a phasing issue with the distributor. This would allow the spark in the distributor to jump to the next cylinder in the firing order which is 90 degrees BTDC and will attempt to turn the engine backwards and can break starter equipment.
If you don't have an ECU then you may have the distributor off by one notch, resulting in the same thing. These may help out.

https://www.youtube.com/watch?v=aWMlNwGW0tM

https://www.youtube.com/watch?v=5a2X9mSSlQY

https://www.youtube.com/watch?v=FHX1yXVyIMg

https://www.youtube.com/watch?v=UYGU7mTwsZc

Bill

 

[Wilhelm]

Hi
Ich habe die IDFs an meinem 347 ford too, hast Du schon alles wirklich genau eingestellt, schwimmer
level, alle 4 vergaser wirklich synchron, duesenstock - mainjet- es gibt hier wirklich viele differed stuff.

Es gibt in USA einen experten Jim Inglese, du findest sicher seine website, Jim hat mir damals fuer meinen GT40 Superformance mit Ford 427 die richtige Vergaserbestueckung genannt und auch geliefert,
Motor lief danach bestens, allerdings es waren Weber IDA.

Willy

 

[Wilhelm]

Sorry, I wrote in German language, because I was thinking you German, when you want I can translate

it !!!!

Willy

 

[Brian Kissel]

Willy You might get a slow response on this. The post is 2 1/2 years old.
Regards Brian

 

[Mick]

Hi Ian, had a similar issue mine although ITB injection, bearing in mind mine has some miles on it (20,000.) so i didn't expect to find this. I noticed my Tacho was sticking at 2500 RPM but the car was running rough and on WOT it was missing. Because my Dizzy has both the crank & cam sensors in it i figure the problem was related to the signal from Dizzy to the tacho. So when i pulled the dizzy i discovered the shaft had worn in the distributor housing and had excessive play so much so that it was hitting one of the senors. Maybe check the play in in your shaft it could be the problem. I had the dizzy rebuilt with a bearing at the base & top of the Dizzy housing to eliminate the issue (still need to be lubricated at every service though to make sure its not wearing.