I have two 800 cfm holley dps that I have had lying around for a
lot of yrs can't even remember how I ended up with them and
have not taken them apart to see if all the correct parts are in them.
one is a 4780 the other a 4780-2 looking at them they have different
styles of throttle plates and thats what the book on holleys I have
say they should have, both 1 11/16 plates. the book says the
metering blocks for the 4780 carb are 134-156 primary, 134-157
secondary and it uses a (12,21) power valve ( have no clue what a
12,21 power valve is) primary power valve. the 4780-2 uses the
6.5 power valve but is using different metering blocks
134-158 primary, 134-159 secondary.

Questions 1, are the air bleeds on these carbs both the same, if so
and no one has tryed to screw with them, what size should the
air bleeds all be.

# 2 do these different metering blocks have different Idle
feed restrictions. I can not find these part numbers on holleys
site, the carbs are old my guess is they discontinued them
went to another number metering blocks.

#3 the 4 corner idle mixture metering blocks that are available,
do you have to have a new main body with removable air bleeds
to make it work.

# 4 one of the carbs is missing the rod that connects the primary
to secondary throttle blades. What can I look that up under ??

#5 do the other then holley brand base plates
fit the holley carbs without problems.