Instructions:
1. Remove the stock GM 245mm impeller hub by boring a 3.380″/3.385″ diameter hole on center in the stock GM 245mm impeller (see Figure 1).
2. Install the Sonnax CH-90CM-27 impeller hub from the outside. Weld around the OD of the impeller hub, making sure it is centered in the impeller. This weld must be leak-proof (see Figure 2).
3. Once the impeller hub is fitted, fixture the impeller assembly in the lathe. Turn the lip of the impeller so that it is 3.80″ from the end of the impeller hub. Then turn the OD down to 10.150″/10.145″ diameter, .40″ from the end (see Figure 3).
4. Install the adapter ring on the impeller assembly as shown in Figure 4 and weld around the OD of the impeller. This weld must be leak-proof.
(more…)