Came across a clean "Granny" 1978 Impala......small block now (of course) w/air.....how difficult to install a big block and th350....I know the 200 in there now will interchange with a TH350...but not sure about the big block....any help would be great!....I know you guys will be thinking WHAT?...Thanks again
I have one in my 1985 and it is the same car as your 1978. I used Hooker Competition Plus headers for a Chevelle but I chose the 4L80e transmission as a big block will break a TH350 or 700R4 transmission. If you want a three speed go for the TH400 instead of the TH350. I also had to make my own cross member for dual exhaust. To cool the added cubes I used a Griffin 1-1/4 inch twin tube radiator (Howe also makes a big radiator for the car as well).
I had to use a Chevelle oil pan from Moroso and even then I had to massage the front cross-member a bit with a sledge for clearance at the front of the oil pan (seven quart Moroso with kick outs 8-3/4 inch deep). Only other problem was the intake manifold and a Dominator carb left only an inch above a flat hood with a Victor intake manifold so I had to go to a medium rise dual plane to run an air cleaner to hide the carb and keep the flat hood I was looking for (my car looks like an old taxi cab and sounds like a small block with a hole in the muffler as I like to keep a low profile).
The beige car is the 582 big block powered car the brown one has a 406 small block under the hood that makes 513 horsepower.
Wow...Thanks for the help....any special motor mounts, and relocation of the trans cross member for the TH 400? Will probably remove all the a/c stuff for more room....any other changes or problems to expect? Thanks a lot!