Almost all Chevies have been available with 4 bolt mains since the late 50's.
they stoped making the 4 bolt main 350 in 2002 hope that helps
1972
Late 1987.
1987 was the last year
Because the bolt stop is broken..they have a plastic bolt stop.
1974 was the last model year for points in a Chevrolet.
To protect ozone, stop using ODS. CFC's is one of the main ODS.
Push the safety lever fully forward to dis-engage the bolt stop. Then the bolt can be removed rearward.
You can stop using it whenever you want.
boogys
stop using silver in nickels
try cleaning the injectors then check the main fuil filter