While back after installing the 185 pulley,My A/F ratio was dangerously lean at top end. Installed NeedsWings fuel management kit with Walboro fuel pump and was still running dangerously lean at top end. Then installed MB fuel pump for the 55 and 63. Didn't think it could be done,but then I was running to rich top end. Luckly Needs Wings fuel management kit has a adjustable pressure regulator to adjust A/F across the RPM's and a brass bleed valve,just for top end A/F adjustments. NeedsWings fuel management kit with the Mercedes fuel pump> A 001 470 65 94 is a proven match. Squirrel Crusher