Chevy Starter Fitment Is Not A One Size Fits All Situation

2015-07-31_19-13-39

It was way back in 1912 when Charles Kettering developed the first electric self-starter. This new-fangled engine starter made it easy for men and women alike to start their horseless carriage, and would signal the end to hand cranking the engine to get your car running.

different

The bolt holes will be parallel to the crankshaft if your car uses a 153 -tooth flywheel/flexplate, and the bolt holes will be offset for 168-tooth flywheel/flexplate.

When it comes to the starters in classic ‘60s and ‘70s Chevrolet musclecars, a starter is a starter, correct? Not exactly. While most starters will look the same, there are slight differences that require noticing. For starters (no pun intended), let’s look at the nose cones. Unless you consider the early starters that used three bolts, and attached to the bell housing, there were basically two nose cones that you need to know about.

Starter pad copy

Most blocks come predrilled for use with either starter, which can lead to confusion.

If your car is equipped with a 12 3/4-inch flywheel with 153 teeth, the nose cone will have two attachment bolt holes across from each other. These holes will be parallel to the crankshaft. If your car uses a 14-inch (168 tooth) flywheel, the attachment bolt holes will be offset (diagonal). This fitment is true for both manual and automatic equipped cars, but, most times a manual transmission equipped car used a cast-iron nose from the factory.

Like the OE starter bolts, these starter bolts from ARP have a specific shank diameter and knurling to help position the starter, and keep it from moving when torque is applied.

Like the OE starter bolts, these starter bolts from ARP have a specific shank diameter and knurling to help position the starter, and keep it from moving when torque is applied.

Not only are there differences in the nose cones, but all is not equal when looking at the starter itself. Chevrolet developed two starters for use in different applications. One was a “standard-duty” starter, while the other was a “high-torque” starter. While the starters look basically the same, there are some external features that allow you to tell the difference.

windings difference

This image shows the case difference between the standard torque starter (left) and the high torque starter (right). The high torque starter utilizes a different case.

As it pertains to the connection of the solenoid to the actual starter motor, although all solenoids are the same length, there was a copper spacer and longer screw used to make the connection in high-torque units. This is because the high-torque starter utilized a different case, field coils, and a completely different armature. This difference is also noticeable in the case.

field windings

A standard torque starter (left) has the solenoid screwed directly to the metal strap that leads inside the starter. The high torque starter (right) has a spacer connecting the solenoid to the metal strap going into the motor.

When using a block-mounted starter, it wise to use the special, knurled starter bolts to correctly position the starter. Using incorrect starter bolts is a leading cause of noisy starters. Installation procedure of the bolts is also important. First, loosely snug the first bolt so the starter is supported, then install and tighten the second bolt. Finally, go back and completely tighten the first bolt.

We can’t talk about starter mounting, and not mention shims. Sometimes, you will need to use a shim to give the proper clearance between the starter drive gear and the flywheel/flexplate ring gear. A rule of thumb is that there should be .030-inch of clearance between the gears when the starter is engaged. In a pinch, a paper clip makes a great gauge for this adjustment. Simply slide the paper clip between the two gears after you manual engage the starter gear. If your starter makes noises when it is starting the engine, there are a few things that can be done to correct the issue.

  • If the starter skips as it is turning the engine, your starter could be too far from the flexplate/flywheel. You could have the wrong starter nose cone, or if you are using shims, remove as many as it takes to get the proper clearance.
  • If the starter emits a high-pitched whine as the engine is turning over,  more clearance is required. Add shims.
  • If the starter growls and the engine doesn’t turn over easily, the gap between the starter drive gear and the ring gear could be too tight. In this instance, shim the starter.
Canon 12455

Always use the factory brace to support the starter. If not, it’s not if your nose cone will break, but when.

This information centers around stock GM starters used on passenger cars and light trucks, and doesn’t apply to later-model vehicles that got the small body gear reduction, aftermarket, or mini starters.

About the author

Randy Bolig

Randy Bolig has been working on cars and has been involved in the hobby ever since he bought his first car when he was only 14 years old. His passion for performance got him noticed by many locals, and he began helping them modify their vehicles.
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