School Me on Converter Spacing

When installing our BPS crank adapter from SBF or Mod motor to a GM torque converter, the adapter properly reduces the converter pilot from 1.702 inch to 1.375 inch to maintain proper centering in the crankshaft. That addresses pilot fit, but it does not eliminate the need to verify converter spacing.

After the transmission is fully seated against the engine, the converter should still have 0.125 inch to 0.187 inch of end clearance before the converter is pulled forward and bolted to the flexplate.

A simple way to check minimum clearance is with a 1/8 inch drill bit. With the transmission fully seated, the drill bit should fit between the converter pad and flexplate. This gives you a quick visual confirmation that the converter is not preloaded into the pump.

If the converter is tight against the flexplate with no measurable clearance, the converter may already be applying forward load into the transmission pump. That preload can damage the pump, affect thrust loading, and create reliability issues immediately on startup.

If the clearance is excessive, the converter must be pulled too far forward to reach the flexplate. That can reduce bolt engagement and may require a properly machined spacer solution depending on the combination.

Converter spacing should always be checked with the transmission fully installed and the converter fully engaged in the transmission. Never use the bellhousing bolts to force the transmission into place.