Question: Which single seater auto-racing formula did 1977 Can-Am season series used

Context articles: 1973 Road Atlanta Can-Am
McLaren M12
1974 Road Atlanta Can-Am
Formula 5000
Monoposto Racing Club
1972 Road Atlanta Can-Am
McLaren M6A
Formula 3 Euro Series
1971 Road Atlanta Can-Am
1977 Can-Am season

The 1973 Carling Can-Am was the second round of the 1973 Can-Am season.
 It was held July 8, 1973, at Road Atlanta in Braselton, Georgia.
 It was the fourth Can-Am race held at the track.
The McLaren M12 was an open-cockpit racing car developed by Bruce McLaren Motor Racing in 1969, solely for the purpose of selling to customers in the Can-Am series.
 The M12 combined elements from two of McLaren's previous efforts, the M6 series and the M8 series.
 One of the more notable owners of an M12 was Chaparral Cars, who used the McLaren in the early 1969 Can-Am season while their own model's development had been delayed.
The 1974 WQXI Can-Am was the second round of the 1974 Can-Am season.
 It was held July 7, 1974, at Road Atlanta in Braselton, Georgia.
 It was the fifth Can-Am race held at the track.
Formula 5000 (or F5000) was an open wheel, single seater auto-racing formula that ran in different series in various regions around the world from 1968 to 1982.
 It was originally intended as a low-cost series aimed at open-wheel racing cars that no longer fit into any particular formula.
 The '5000' denomination comes from the maximum 5.0 litre engine capacity allowed in the cars, although many cars ran with smaller engines.
 Manufacturers included McLaren, Eagle, March, Lola, Lotus, Elfin, Matich and Chevron.
The Monoposto Racing Club is a single seater, open-wheeled motor racing club in the United Kingdom.
 Its members race a variety of single seater race cars ranging from 600cc Jedi's to 2000cc Formula Three and Formula Renault cars. "
Monoposto" is Italian for 'Single Seater'.
 As of 2010, it is the largest single seater championship in the UK, with over 60 regular race entrants.
The 1972 Road Atlanta Can-Am race was the second round of the 1972 Can-Am season.
 It was held July 9, 1972, at Road Atlanta in Braselton, Georgia.
 It was the third Can-Am race held at the track.
The McLaren M6A was a race car developed by driver Bruce McLaren and his Bruce McLaren Motor Racing team for their entry in 1967 Can-Am season.
 As a replacement for the team's M1Bs from 1966, the Chevrolet-powered M6A's improved design earned Bruce McLaren and his team their first of multiple Can-Am championships.
 After the M6As were replaced by the M8A in preparation for 1968, McLaren and technical partner Trojan developed the M6B which was sold to customers for use in Can-Am as well as other racing series.
The Formula 3 Euro Series was a European-based junior single seater formula for Formula Three chassis that was launched (in its current form) in 2003 as a merger of the French Formula Three Championship and German Formula Three Championship.
 The Formula Three category, including this championship, is part of the established career ladder up which European drivers progress to the Formula One world championship, the highest form of single seater racing defined by the Fédération Internationale de l'Automobile (FIA), motorsport's world governing body.
The 1971 Road Atlanta Can-Am race was the third round of the 1971 Can-Am season.
 It was held July 11, 1971, at Road Atlanta in Braselton, Georgia.
 It was the second Can-Am race held at the track.
The 1977 Can Am season was the tenth running of the Sports Car Club of America's prototype-based series.
 Despite the revived name, however, the new series was entirely unrelated to the previous series which had folded in 1974.
 This series used Formula 5000 Lola T332s with fenders added.
 Patrick Tambay was declared champion, winning six of the nine races that year for Carl Haas.
 While Lola chassis dominated the series, a Chevrolet powered Schkee DB1 driven by Tom Klausler won the first race at Mont Tremblant.
 Formula One driver Gilles Villeneuve came in third at Road America in a Wolf.
 While Chevrolet was not the only engine supplier, they swept the entire season.
 This season also marked a resurgence of interest in SCCA events, with Can Am accompanying F5000 and the Trans Am Series seeing a mild resurgence in the eighties.