Actually, my Cobra has worked great for years, but I had a slipped balancer, which may have continued to slip a bit here and there. Of course every time I reset the timing, things got worse and worse and detonation finally took out a piston and now with my latest rebuild, I have to start over. And with no history of what worked, and what didn't as far as igniton is concerned.
However, through experimentation, I found that with a mech advance only carb, the engine runs very hot with the timing down around 10 or 12 deg like Ford specs. With my cam, the Barry Grant advice is an intial of 16-18. I am currently running 20 intial with 38 total and it is fine. However, I caution you.... I know when I had 28 intial, I was getting some knocking. I couldn't hear it, but I could feel it. It just feels like the engine doesn't want to rev freely, and if you go too far, you can really feel the engine fighting the rpms.
However, I feel there is a little mroe room for advance at idle as I did have better reponse before, and the reponse keeps improving the more advance I dial in.
Cleaning up the idle? I tried to find what advance gave me the best vacuum at idle. It was 38 Deg BTDC. But it will knock there under load until the revs get up. If I could fit a vacuum dist on my engine, I would.
The best thing would be to start quite high intial for a good idle, good response, cool idle, and then have the timing, advance more slowly than normal. This way, you get back on track (as the rpms build) to the best timing profile where you want more power (with a standard tranny).
It's been a compromise. Hot engine with retarded advance, and uncertain about detonation with too high an advance..
I tend to think you can get away with a high intial as you won't develop full HP at lower rpms in such a light car, plus who ever starts accelerating at 1000 rpm? Probably have it from 1500 to 2000 just to pull away from a stop sign.
Someone in this forum gave me this link, it's seems quite interesting:
http://www.kitcarmag.com/techarticle...ine/index.html
I will check out the website you mentioned too. Thank-you.
I'm pretty sure I am down to carburation for my low idel after a WOT run. I discovered that if I leave the low idle, it will come back up after about 15 seconds, like it was temporarily swamped with too much fuel. I also just noticed if I brake hard, the engine rpm will also drop (all this with clutch disengaged, of course), but comes back almost immediately, as if it were starved for fuel, vs too much. None of it is a big deal, but I like tinkering....er....most of the time.