my BBC needed 18* initial, 20* mechanical
Thats 38 degs .. ne petrol vechile with inter4combustion engine will require any more than 36 degs , over the last 100 yrs plus... rather the opposite on modern unleaded fuel forumula and lower octanes...
you have simply patched a problem not fixed it, and patching WILL kick u in the butt later on.
With the lean burn u have a slower burn, which increasing the advance will cover up.. patch
I was at 71 on the primary's. Now 74. I new that too much timing might be an issue but to isolate the problem I test drove with jet change only. It helped
you confirmned the lean issue here
I then turned the secondary idle screws out 1/4 turn on all 4
The idle circuits have very little significant difference on mixtures over walking pace in top gear.. u still have a jetting issue.. The higher speed air being still sucked past the venturis metered by jets, at very high engine vaccuums.
And if have a non egr engine which runs VA on manifold vaccuum so intial +Va= idle u now have a n idle of 18+14 =32 and overall 52 10 deg above a max of 40/42 if dialing in without a knock sensor and data logger.
ANY mild street cam will only require a idle advance of 14 to 16 degs MAX stronger cam 16 to 18, wild/ track 18 to 22 degs for best stable (not best) idle.
you will find under WoT getting up around the 4K rpms that engine wil be leaning out, melting pistons and stuff.. espec if lean AND runing extra advance to fire the lean condition and slower burn.
There is only 1 way to dial in
Get the timing into ball park..
idle around 14 degs
Total around 34
all up under 42.
THEN get the mixture correct
Idle circuit 14.8 to low 15s
WoT 11.5 to 12.5 max
Cruise mid 15s
do the timing again with locked dizzie as I descibe above.. establish the actual idle/ WOT advances... then adjust the cent and VA advances to suit keeping the all up under 40/42 degs , unless have a knock sensor...
There are no short cuts, roundabout way or patch ups ... these result in engines having so called part failures ....
This is the 21 st century, things like data loggers are cheap compared to a engine build now....20th century unless one had very deep pockets all we had where COx meters to tune with, and they where damn expensive.
(mine has been tucked away under a bench for many yrs now... obsolete).