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BJ 8 Ignition timing

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DavidThorn

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Having problems with igntion timing on my car. If timing is set correctly with stobe light car lacks power and returns about 18 to the gallon but runs sweetly at tickover and can be slowed down to about 600 revs. Advancing the ignition by about 10 degrees makes the car run much better under load and returns 24 to the gallon - but tickover is uneven and lumpy and will not slow to below 1000 rpm. Any ideas a friend looked at the distributor and felt that it was not badley worn. The vacum on the adavance and retard seems to be holding (tested by sucking on the pipe). I suspect that the springs may be to weak (or perhaps to strong) Anyone any ideas?
 
What degree advance are you setting initially with the
engine at idle and the vacuum disconnected.???-Keoke
 
David,

most likely the mechanical advance mechanism is not working the way it should, as suspected by you. I guess that the springs were worn and replaced by the PO, maybe with springs that don't have the proper rates due to lack of originals.

If you are tired of fiddling with your distributor, check this out. I have put it in my car and it's a dream. Car runs smooth when idling and under load due to spark balancing. I got a 10% better mileage out of it, although I had previously replaced the worn, original distributor by a Mallory unit with Pertronix ignitor (pointless ignition system). Plus you don't have to worry about spares. Cap and rotor are standard Bosch items (recommended to be replaced every 20,000 miles) with the only moving parts being the shaft and the rotor. Everything works electronically, even the vacuum is measured electronically and you can select between 16 different advance curves via a switch. Though the look is still classic.

If you need one, contact me.
 
Try the factory setting of 15 degrees BTDC at 600 rpm with the vacuum disconnected to get started. Then check what the maximum advance is when revved. Should be 35 degrees BTDC.

Cheers,
John
 
Yes Have now set it to that - in fact that is not far off the setting I had guessed to in the first place. It seems to be running much sweeter on tick over,which I had to slow down considerably that aunfortunate sucking (induction )noise has also gone.It seems to pull well also . Will report back on fuel consumption.
 
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