KiwiTR6 Posted April 12, 2023 Report Share Posted April 12, 2023 I'm planning to fit a CB Performance Black Box to my car to enable me to set up a custom ignition curve for my current engine and possibly a high performance engine I may build some time in the future. This engine seems to like 10 degrees advance at low idle but from there up I haven't investigated the advance which will be linear up to the maximum. To help me formulate something reasonably sensible to start with I'm wondering if anyone has a data table they use in a 123/Tune (or similar) for a 73 CR model? The fuel I use here is 95 RON non-ethanol blend and the Black Box also has a vacuum input which the standard distributor doesn't. Any help or advice will be gladly received. Quote Link to post Share on other sites
iani Posted April 12, 2023 Report Share Posted April 12, 2023 27 minutes ago, KiwiTR6 said: I'm planning to fit a CB Performance Black Box to my car to enable me to set up a custom ignition curve for my current engine and possibly a high performance engine I may build some time in the future. This engine seems to like 10 degrees advance at low idle but from there up I haven't investigated the advance which will be linear up to the maximum. To help me formulate something reasonably sensible to start with I'm wondering if anyone has a data table they use in a 123/Tune (or similar) for a 73 CR model? The fuel I use here is 95 RON non-ethanol blend and the Black Box also has a vacuum input which the standard distributor doesn't. Any help or advice will be gladly received. On my Mk2 PI Saloon I am running: 1500 RPM 10.0 2500 RPM 24.0 4000 RPM 29.0 Quote Link to post Share on other sites
KiwiTR6 Posted April 13, 2023 Author Report Share Posted April 13, 2023 (edited) 20 hours ago, iani said: On my Mk2 PI Saloon I am running: 1500 RPM 10.0 2500 RPM 24.0 4000 RPM 29.0 Thanks Ian. That's a start, but do you have more data points than that? I was hoping to be able to enter a curve for which I would need maybe 10-20 values. Edited April 13, 2023 by KiwiTR6 correction Quote Link to post Share on other sites
iani Posted April 13, 2023 Report Share Posted April 13, 2023 (edited) 3 hours ago, KiwiTR6 said: Thanks Ian. That's a start, but do you have more data points than that? I was hoping to be able to enter a curve for which I would need maybe 10-20 values. The 123 will smooth out the curves, I don't think it will let you add that many values in any case. You can also add MAP adjustments but unless you have modified your system I doubt that will be of use to you. Edited April 13, 2023 by iani Quote Link to post Share on other sites
DRD Posted April 13, 2023 Report Share Posted April 13, 2023 This the advance curve of my distributor from the DD who modified it for my tuned engine. Quote Link to post Share on other sites
KiwiTR6 Posted April 14, 2023 Author Report Share Posted April 14, 2023 On 4/14/2023 at 12:45 AM, DRD said: This the advance curve of my distributor from the DD who modified it for my tuned engine. 20 deg max advance and 2 at idle, I don't think my engine would run at that. Currently I have 10 deg at idle and I'm pretty sure over 40 at revs based on the degree marking tape I've fitted to the front pulley. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted April 14, 2023 Report Share Posted April 14, 2023 (edited) 1 hour ago, KiwiTR6 said: 20 deg max advance and 2 at idle, I don't think my engine would run at that. Currently I have 10 deg at idle and I'm pretty sure over 40 at revs based on the degree marking tape I've fitted to the front pulley. That is the profile of the distributor curve before it is fitted and timed in an engine. Just add or subtract the degrees depending on your static distributor setting. ie. At 10 degrees static BTDC the dynamic tickover would be at 12 ish degrees, at 2500 rpm it would be 30 degrees.( max advance) Edited April 14, 2023 by BlueTR3A-5EKT Quote Link to post Share on other sites
DRD Posted April 15, 2023 Report Share Posted April 15, 2023 9 hours ago, BlueTR3A-5EKT said: That is the profile of the distributor curve before it is fitted and timed in an engine. Just add or subtract the degrees depending on your static distributor setting. ie. At 10 degrees static BTDC the dynamic tickover would be at 12 ish degrees, at 2500 rpm it would be 30 degrees.( max advance) Spot on, my actual setting is about 14 btdc at idle. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted April 15, 2023 Report Share Posted April 15, 2023 40 minutes ago, DRD said: Spot on, my actual setting is about 14 btdc at idle. Makes sense as 32 degrees BTDC is said to be the max advance the TR engine tolerates before detonation/pre ignition when running on regular grades of fuel. Quote Link to post Share on other sites
DRD Posted April 15, 2023 Report Share Posted April 15, 2023 1 hour ago, BlueTR3A-5EKT said: Makes sense as 32 degrees BTDC is said to be the max advance the TR engine tolerates before detonation/pre ignition when running on regular grades of fuel. I run it on a min of 99RON as the compression ratio is a bit higher than standard. Quote Link to post Share on other sites
KiwiTR6 Posted April 15, 2023 Author Report Share Posted April 15, 2023 23 hours ago, BlueTR3A-5EKT said: That is the profile of the distributor curve before it is fitted and timed in an engine. Just add or subtract the degrees depending on your static distributor setting. ie. At 10 degrees static BTDC the dynamic tickover would be at 12 ish degrees, at 2500 rpm it would be 30 degrees.( max advance) Thanks Peter, that makes a lot more sense. Quote Link to post Share on other sites
unclepete Posted April 17, 2023 Report Share Posted April 17, 2023 (edited) Sorry Wrong Subject! Edited April 17, 2023 by unclepete Quote Link to post Share on other sites
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