The trickiest part of this one is that the maker bought the car at an estate sale without knowing what was really under the hood. The seller believed it was a 350, but after inspecting the car the maker found casting code 3591509 and identified a 400 small-block Chevy. On top of that, the previous builder has passed away, so there is no one to ask about what went into the engine. The maker is now adjusting the carburetor while openly admitting to knowing nothing about carburetors, which is a bold way to learn.
The hardware list is solid for a car that was clearly raced by the previous owner. A Holley street hp 750-cfm double pumper sits on a Weiand team g intake, with World products sportsman 2 heads up top and an Msd Streetfire hei distributor. Hedman headers feed a 3-inch exhaust. Behind the engine is a Th350 with a manual valve body, and out back there are 3.73 gears with posi.
What stands out is that the transmission does not slip and responds well whenever the throttle is applied. The idle sits around 1400 rpm, though at one point it was running 1100 with a choppy, cam-like sound. Cruising at 40 mph turns about 3000 rpm, which made the maker suspect very tall gears. A spin test showing 3.75 driveshaft turns per one full wheel turn proved the 3.73 gears were correct, and I think running that test instead of guessing was the right move.
The open question is the unknown stuff: cam specs, bottom end, and torque converter specs are all a mystery, with the maker guessing at a high stall behind a huge cam. The idle screw is backed out and not touching the linkage. The goal is a more streetable cruising and idle rpm, and a built 200r4 is wanted down the road but is out of reach financially right now. In my view, collecting parts slowly while running the current engine until it fails seems a reasonable path.