Ayuh,...... What pitch is the prop,..??
Go up in pitch, to bring the Wot rpms down to a True, 4600 / 4800 rpms,.... in other words, verify the tach,....
The 888 is a 1.50:1 ratio, 'n the 233 was a 1.32:1 ratio,....
I say was, because that ratio hasn't been available for decades,...