| Moderated by: Greg Fletcher | ||
| Author | Post | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
SpeedyMitch Member 
|
I've been playing with the timing in my stock '73 and have some observations that others may be able to confirm or deny. 5-degrees before TDC - lumpy idle at about 750 RPM. Some low-end torque but seems flat after about 5k RPM. 10-degrees - idle becomes smooth at about 900 RPM. Less low-end but better response at highway speeds. 15-degrees - high idle (can't seem to bring it down with carbs), no low-end, no better at highway speeds. Just about everthing I have read says 10 to 15 degrees is 'best' but that has not been my observation. Note: all observations meticulously measured using my seat-o-the-pants-o-meter. |
|||||||||
|
subwoofer Member
|
The critical part is the advance at WOT (or vacuum disconnected) and high RPM. It should not be more than 30 degrees, 28 is good. That will bring your idle advance down to ~10 degrees. Unless you change weights and springs, you are stuck with what you get - rev it up and get the high RPM advance right. You will not ruin the engine idling anyway. The stock JH spec 907 has way too low compression, I run a European 907 from a '78 Lotus Eclat, and 9.5:1 compression and DellOrtos really make a difference. -- Joachim |
|||||||||
|
Jensen Healey Super Moderator 
|
Yes, total advance is the limiting factor. I use a MSD6A and minor timing settings make no difference. Kurt Don't tell the MGB guys about our advance curve! |
|||||||||
|
StevenD57 Member 
|
Here is the advance table I am currently running. This is with a standard low compression stock motor. Attachment: sparktable.png (Downloaded 73 times) |
|||||||||