The way you can tell is by the suffix code on the engine block pad just below the the passenger side head and by the build sheet of the vehicle with the FI engine option listed on it. To properly indentify an engine block, there are three identifiers, the engine ID on the pad I mentioned, the casting number and date code. The most informative identifier is the engine ID on the pad below passenger side head.
CS = 283-cid 315-hp V-8 with 11.0:1 compression ratio, three-speed manual transmission, high lift camshaft, and fuel injection
CR = 283-cid 275-hp V-8 with 11.0:1 compression ratio, three-speed manual transmission with fuel injection.
V-8 283-cid 275-hp fuel-injection engine
V-8 283-cid 315-hp fuel-injection engine
See: http://www.corvetteactioncenter.com/specs/c1/1961/61id.html & http://www.motorera.com/corvette/1960/vet61.htm & http://corvetteactioncenter.com/specs/c1/c1serial.html for more information.
The build sheet showing those option codes is the only true way to verify if the FI engine originally came with your car.
Original build sheets are normally found under passenger side seat, on top of fuel tank or in headliner.
Build sheet information
There is nothing that cannot be altered. The body is the same. The only difference would be the decals/emblems that could be attached later by anyone. The only real proof of originality would be the build sheet of the vehicle. Of course, the most important thing would be the engine itself with the two suffix codes CR or CS on the ID pad. Here is a picture of the original ID tag on the fuel injection plentum for 1961:
Distributor number for 275hp fuel injection
Distributor number for 315hp fuel injection
A numbers matching 1961 corvette with all the options is worth $149,000
All options are found on the build sheet.
For technical questions email : email@example.com
From 1960 to the present the VIN sequence number is XXXXX on the passenger side of the engine block. If your block has the CS or CR suffix and the last six of vin that matches the vin on the car, That proves it is a fuel injection corvette and is numbers matching.
Anyone telling you that you don't have the fuel injected body is probably just jealous of what you have and trying to devalue it with a con to buy it cheaper than what it is truly worth. They are basically saying your body has been replaced or the fuel injection emblems are not in the right place or missing. There is no difference in the body itself. Replacement body's are available. What makes your car what it is, is the engine itself.
Here is more information:
1961 Corvette Fuelie Show Condition Fresh Frame Off Restoration Silver/Red
The front of the 1961 Corvette looked like the 1958, 1959 and 1960 models. But the rear was restyled with four round tail lights, which became a Corvette trademark.
The wheelbase of the 1961 Corvette was 102 inches. The overall length from bumper to bumper was 177.2 inches. The height from top of the roof to road was 51.6 inches and the overall width was72.8 inches. The 1961 Corvette weighed 3,035 pounds and the fuel tank held 16.4 gallons of gasoline.
The base engine was a 283-cubic-inch V-8 that had a four-barrel carburetor and an output of 230 horsepower and a compression ratio of 9.5:1. A 245-horsepower 283 engine with two four-barrel carburetors and a 9.5:1 compression ratio was available for $150.65 extra. The same setup with 270 horsepower and a high-lift camshaft cost another $182.95. Two more 283 engines with 275 or 315 horsepower and fuel injection instead of carburetors cost $484.20 extra each.
The base price of the 1961 Corvette was $3,934, but there were many options available that would drive up the price. Powerglide automatic transmission cost $199.10 extra, while a four-speed manual transmission cost $188.30 extra over the basic three-speed manual. Power windows were $59.20 extra and a signal-seeking AM radio would set you back $137.75. A power-operated convertible top cost $161.40, while a fiberglass hardtop was $236.75. Wide white-wall tires cost $31.55 more than the standard black walls. A heater was an extra $102.25. A two-tone paint treatment cost another $16.15. A Positraction limited-slip differential was $43.05. Heavy duty brakes and suspension cost $333.60 extra.
Only Early corvettes up to early 1961 without Fuel Injection had tachs driven off of the generator. Late 61 and later were driven off distributor.
The hole in the center of the firewall is for distributor driven tach cable which goes with the rest of the evidence of fuelie origin on early 57-61 models.
Fuel cars has the washer bottle assembly moved from driver side to passenger side to accommodate the FI Air Cleaner. Do you have an air cleaner on yours? Someone could decide they don't want a washer or drill holes and move it. They can also install a different type air cleaner. Traffic accidents & repairs by body shops can remove bent original parts and replace with junk yard or aftermarket parts, front clips etc.
The bottom line is does the Vin on the engine match the Vin on the car?
Carb & fuel injection differences