The Maserati Mistral 3700 GT is one of the finest GT machines produced in the 1960s, right along with Maserati’s 3500GT and Sebring. They all share the AM101 inline-six, ZF gearboxes, and Salisbury rear axles, beneath coachwork from Touring, Michelotti, or Frua. This 1965 Mistral has been with the same owner since the 1970s, and it remains largely unrestored – albeit with a so-so repaint and re-dyed (yellow) interior. It had been off the road for over a decade until recently when the owner delivered the car off at a little British repair shop, owned by a friend and confidant. The owner’s budget was limited, so we were asked to get every ready for a season on the backroads while leaving the cosmetics alone.
This car originally had Lucas mechanical fuel injection. That system was swapped out for a trio of Weber DCOEs in the 1970s. Here we are finding the actual Top Dead Center with a dial indicator – there are no timing marks on the crank pulley or flywheel. It is a little crusty under the hood. But, after a valve adjustment, the compression came back up to within specification.
Typically, service to a multi-point Magneti distributor should be done on a distributor machine. I’m working at a friend’s shop – we didn’t have one on hand – so, here is the workbench approach! The Mistral’s AM101 engine utilizes two plugs per cylinder and a single distributor. It is critical to phase the points properly while setting the gap, this applies to any dual-point distributor, like the one commonly found on Ferraris. The Mistral manual specifies a .5 to 1-degree gap between the two circuits – this slight delay does make the engine perceptibly smoother at idle. The “cheater workbench Syncrograph” method shown above involves marking out 1 degree of rotation on the distributor, followed by setting the point gap, adjusting the contact to the cam, and using a pair of multimeters (buzzer enabled) to sequence the opening and closing of the points together.