Vacuum advance information and myths
re. post 85
"GM, who used MVA, could not meet the stricter HC emissions standards coming into effect in the late 60s & had to switch to PVA."
So its been claimed.
But evidence shows that Chevy had used a timed port before needing to meet 1968 emissions requirements.
^This is a 1965 Cheverolet L-78 with a 4150 list 3124.^
Next
^This appears to be an original 4150 Holley List 2818^
As shown in this diagram.
re. post 85
"GM, who used MVA, could not meet the stricter HC emissions standards coming into effect in the late 60s & had to switch to PVA."
So its been claimed.
But evidence shows that Chevy had used a timed port before needing to meet 1968 emissions requirements.
^This is a 1965 Cheverolet L-78 with a 4150 list 3124.^
Next
^This appears to be an original 4150 Holley List 2818^
As shown in this diagram.