Vacuum advance information and myths

440 Mike Post #102.

When my car was built, leaded fuel was in use which allowed higher comp ratios. Nothing needs to be done to the idle timing because the engine doesn't ping at idle! The centri curve &/or total timing at idle may need tweaking on a stock engine.
On the LS1 engines, WOT timing was about 27*. These engines idled at 22*BTDC!!!! So MVA is alive & well in modern FI engines!!

I have an article where two 1970s engines on PVA were converted to MVA. They were Pontiac 455 engines, one with man trans the other auto & the specific aim of the project was to see what changed with the switch from PVA to MVA. If you like, I could post the results, which were veeeery positive.