Anybody ever do an all out rebuild on a Holley 780?

[JL8Jeff]

I finally got around to tearing into the old Holley 780 for the SS396. It's a very complete and original carb #4557 which is unique to the 1970 L78 and LS6 engines. The first difficult step was getting the secondaries to move. They were rusted shut! PB Blaster, heat, carb cleaner and more heat and finally the hammer! Got em loose. So I managed to get the base plate off and get the butterflies off and the throttle shafts out. I'll be stunned if it actually runs because the rebuild kit does not include new bushings for the shafts so I had to reuse the old ones. Lots of steel wool and wet/dry sandpaper to clean up the rusted butterflies. I think they'll work. I figure I have nothing to lose trying to rebuild it myself except the $42 for the rebuild kit. If it doesn't run right, I'll send it out for a pro rebuild and correct replating. It looks like it might take a couple of days to get it done, but then I'm in no hurry so it should be interesting.

[WildBillyT]

I did two double pumpers before... can you get a Holley "Trick Kit" for it?

[johnjzjz]

a few ideas -- we glass bead ( corn huskers ) the parts with no air or fuel -passages can get clogged easy -- soak it in a gallon of enviro carb cleaner gunk 2 / 3 days -- it comes in gallon cans does not work as good as the old stuff did but its all that is out their -- the throttle blades have screws that were pined over, need to be lock tighted but will be a real thing if need to remove again ( from Holley they are squashed like a rivet ) a small amount of looseness in throttle shafts is ok -- don't worry about that -- set floats at the bottom of the bowl screw hole with car on a flat and running ( stock pump ) elect pump can do still cold and not running ) Caution fuel can leak all over the place -- about a turn and 1/4 is all you should need on mix screws - we tap into full time vacume like the dist has and adjust to best possible vacume and smoothness with a vacume gague -- 780s came for the most part Vacume secondaries some were converted to DP -- you can tune it to respond to light throttle 4 BBL with spring change in diaph if its a vacume carb -- let me know i have those and can send we don't do many vacume carbs any more -- jz

[Tru2Chevy]

Jeff, Tim is pretty sure he's got some of those bushings laying around.

- Justin

[JL8Jeff]

I think I should be ok with these bushings. I just cracked open the bowls last night and it definitely needs to soak in some cleaner. It has a nice white, crusty buildup inside.