Austin Branson Posted April 22, 2021 Report Share Posted April 22, 2021 Greetings, oh sage ones! I’m having a few problems with the car (1974 supercharged CF), and I think the ignition switch (aftermarket, dash mounted) might be the culprit. The engine is running very poorly, but perks up if I supply 12 volts to the coil (its a 9 volt Flamethrower). I’m considering changing it to a 12 volt coil, as I’m not completely convinced as to the reliability of the 9 volt supply. Or maybe I should bypass the ballast resistor wire, and fit a stand-alone ballast resistor (assuming it exists). I’m no electrician. What do you guys think? Austin Quote Link to post Share on other sites
Mike C Posted April 22, 2021 Report Share Posted April 22, 2021 Your problem is probably the ignition switch, not the ballast resistor. You're bypassing the switch when you apply 12V directly to the coil. I doubt that a new ballast resistor will fix the problem. Are all your ignition wiring connections secure? Quote Link to post Share on other sites
Austin Branson Posted April 28, 2021 Author Report Share Posted April 28, 2021 Hello Mike, thanks for coming back. I spent all weekend on this. I found 3 problems. The ignition switch was buggered. A garage mechanic had twisted the wretched thing so badly that one of the terminals was loose. The junction at the positive coil terminal of the 12 and 6 volt wires was poor,and the coil was faulty. It seems a lot better now, but static timing is 18 BTDC! Cheers Austin Quote Link to post Share on other sites
Mike C Posted April 28, 2021 Report Share Posted April 28, 2021 Do you get pinging on WOT low engine speed? If you do retard the timing until the pinging just stops. Quote Link to post Share on other sites
Austin Branson Posted May 21, 2021 Author Report Share Posted May 21, 2021 On 4/29/2021 at 1:30 AM, Mike C said: Do you get pinging on WOT low engine speed? If you do retard the timing until the pinging just stops. Nope. No pinging here. Quote Link to post Share on other sites
Mike C Posted May 21, 2021 Report Share Posted May 21, 2021 7 hours ago, Austin Branson said: Nope. No pinging here. Then it might be a good idea to check the alignment of the front pulley timing marks with actual piston TDC. A PI car will definitely ping at 18 deg BTDC, WOT, low revs- I wouldn't expect supercharged cars to be that much different. Quote Link to post Share on other sites
Tim D. Posted May 22, 2021 Report Share Posted May 22, 2021 My supercharged car runs at around 12-14 BTDC at idle. I have an electronic programmable ignition so have more flexibility with the advance curve, but this amount of advance seems about right. Quote Link to post Share on other sites
Austin Branson Posted May 24, 2021 Author Report Share Posted May 24, 2021 On 5/22/2021 at 1:09 AM, Mike C said: Then it might be a good idea to check the alignment of the front pulley timing marks with actual piston TDC. A PI car will definitely ping at 18 deg BTDC, WOT, low revs- I wouldn't expect supercharged cars to be that much different. Hello Mike, Yes, I’ve done that. All seems good. I have to to elucidate, I didn’t set the ignition timing at 18 BTDC for performance reasons, but to get it running. At the recommended 10 BTDC, it simply wouldn’t run. Very strange. This engine is supposed to tickover at 4 ATDC. No chance! Austin Quote Link to post Share on other sites
Austin Branson Posted May 24, 2021 Author Report Share Posted May 24, 2021 On 5/22/2021 at 9:19 AM, Tim D. said: My supercharged car runs at around 12-14 BTDC at idle. I have an electronic programmable ignition so have more flexibility with the advance curve, but this amount of advance seems about right. Hello Tim, I’ve bought a 123TUNE, but I haven’t fitted it yet. Could you let me have your advance curve, please? Many thanks, Austin Quote Link to post Share on other sites
Mike C Posted May 24, 2021 Report Share Posted May 24, 2021 12 minutes ago, Austin Branson said: Hello Mike, Yes, I’ve done that. All seems good. I have to to elucidate, I didn’t set the ignition timing at 18 BTDC for performance reasons, but to get it running. At the recommended 10 BTDC, it simply wouldn’t run. Very strange. This engine is supposed to tickover at 4 ATDC. No chance! Austin "but to get it running"-the pulley timing marks might be wrong- the outside slipped on the harmonic balancer. Quote Link to post Share on other sites
Austin Branson Posted May 24, 2021 Author Report Share Posted May 24, 2021 1 hour ago, Mike C said: "but to get it running"-the pulley timing marks might be wrong- the outside slipped on the harmonic balancer. Hello again Mike, yes, I’ve done that too. All seems good. I really appreciate your interest. Austin Quote Link to post Share on other sites
Mike C Posted May 24, 2021 Report Share Posted May 24, 2021 No worries. Tim's advance curve could be the way to go. Quote Link to post Share on other sites
Tim D. Posted May 24, 2021 Report Share Posted May 24, 2021 4 hours ago, Austin Branson said: Hello Tim, I’ve bought a 123TUNE, but I haven’t fitted it yet. Could you let me have your advance curve, please? Many thanks, Austin 12 degrees BTDC static My curve is: 500 0 1000 0 1500 0 2000 4 2500 10 3000 16 3500 20 I also have boost retard 4psi -4 8psi -6 And Vacuum Advance of 10 degrees at 8psi vaccuum (slightly odd units) cheers Tim Quote Link to post Share on other sites
Peter Cobbold Posted May 24, 2021 Report Share Posted May 24, 2021 Austin, You have a 7,75:1 compression ratio head so 18 BTDC is bang on for static timing. Peter Quote Link to post Share on other sites
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