Usman Minhas (90) and Joe Kendall (61) led the way for Grantham with Thomas Giles (33) top scoring for the hosts.
Grantham's Muhammad Kaleem took six wickets for the loss of 21 runs.
A point behind are defending champions Bourne, who left Nettleham with a six-wicket success.
Mitchell Slattery was the pick of the Nettleham batsmen with 58, but Ben Woodward (5-24) worked his way through the home side's batsmen.
Sam Evison hit 89 runs for Bourne with Carl Wilson adding an unbeaten 50.
Another side with a 100 per cent record are Sleaford, although seven points behind Grantham.
Andy Hibberd (78) led the way in his side's 92-run victory at sixth-place Woodhall Spa, Alex King and Alfie Lindsey taking three wickets apiece.
Ross Dixon's unbeaten 26 was the highest score for the Spa men, as Sleaford's Thomas Shorthouse also took three wickets.
Basement boys Skegness continue to search for their first win.
This week they lost by 86 runs as they hosted fourth-place Lindum.
Pranav Pothula's 123 set the tone before Norman Brackley (39) top scored for the seasiders.
Bracebridge Heath's eight-wicket win at Louth saw them move up to seventh as they leapfrogged their opponents.
Kenyan Remembrance Nyathi hit 81 runs for Louth as the visitors' Joseph Mansford took three wickets.
In response Taylor Fell's 88 not out helped Bracebridge to victory. Andrew White took the two visiting wickets.
The only home success of the weekend saw Market Deeping, in 10th, beat ninth-place Spalding by 10 wickets.
Ethan Lawrence hit 57 runs for Spalding but openers Josh Smith (96) and Connor Gillett (63) enjoyed unbeaten knocks. Deeping's Smith and Hayatullah Niazi both claimed three victims.
Results: Scunthorpe Town 90 all out, Grantham 236-7; Skegness 173 all out, Lindum 259-7; Louth 138 all out, Bracebridge Heath 139-2; Market Deeping 177-0, Spalding 173 all out; Nettleham 166 all out, Bourne 167-4; Woodhall Spa CC 113 all out, Sleaford 205 all out.