ACH24 :

Research by the ACH24 association into the 1924 24 Hours of Le Mans has led to a number of changes in the Rolland-Pilain crews compared with the crew compositions published to date in the various books on the event.
In the May 30, 1924 edition of L'Auto, the list of drivers mentions Gérard Marinier and Antoine Dubreuil on the Rolland-Pilain N°20.
In L'Auto of June 14, the Saturday of the race start, the entry list still features Gérard Marinier - Antoine Dubreuil on the Rolland-Pilain N°20. In the same newspaper, the 2-page special edition shows the technical table with Chalamel and Very on the Rolland-Pilain N°20. Was it a crew change at the weigh-in on Friday?

In the June 15 edition of L'Auto, the standings after 6 hours of racing mention Chalamel and Very. Also in L'Auto June 16, 1924, Chalamel and Very completed 53 laps at the halfway point. The other Saturday, June 14, 1924 newspapers also quote Gérard Marinier - Antoine Dubreuil on No. 20.
The next day, Sunday June 15, all modified in Chalamel - Very on the 20, (Ouest-Eclair doesn't mention the drivers, nor does La Vie Automobile).

All these documents suggest that the Rolland Pilain crews were reshuffled at or before Administrative Checking and Scrutineering De Marguenat joins Gaudin in the Rolland Pilain II N°18, while Guignard moves to the Rolland Pilain I N°17 with Delalande, while Sire moves to the Rolland Pilain III N°19 with Tremel; but above all, it's Chalamel and Very who drive the Rolland Pilain IV N°20 in the race. At the Administrative Checking and Scrutineering :, Chalamel presents Rolland-Pilain. The archives of La Sarthe of June 14, consulted at the Médiathèque du Mans, confirm the conclusion: Marinier-Dubreuil on the entry list, Chalamel-Very at the start... and in La Sarthe of June 15 with Marinier and Dubreuil.