Hi ! Your engine number 33080, is not a number associated with identifying CB750 crankcases as 'sandcast'. With a number of 33080, your cases' exterior will be smooth - pressure cast - and NOT having the rough finish, characteristic of the 'sandcast' finish which used a gravity or 'drop' casting process. To date, i am not aware anyone knows of any available definititive information identifying the engine numbers used on the last set of 'sandcast' crankcases manufactured by the Honda factory. However, it is common knowledge, available through Honda factory information, frame number 7414 carried the last set of 'sandcast' crankcases. Based on experience shared by club members with their familiarity of the Honda factory frame/engine numbering system, it is safe to say the highest 'sandcast' crankcase engine number was give or take no more than 100 to a few hundred numbers from 7414. In fact, if you study the the VIN Directory, you will note the frame number 7319 carries engine number 7375 with a crankcase casting date of September 4, 1969. By September, 1969, Honda was stamping the month of manufacture on the riveted on frame tag. I personally have seen frame number 6623 with a manufacture month of September, 1969. I have also seen pictures of frame number 79xxx carrying a pressure cast set of cases with corresponding 79xx numbers with a manufacture month of September 1969. The range of these VIN's in the same month support the belief no "sandcast" machines could have been built later than September 1969. You are right about your bike having many of the identifying characteristics of a 'sandcast' CB750. Other than the upper & lower crankcases not being sandcast, i am not aware of any profound differences between a Late Production sandcast machine & the pressure cast machines. I am not familiar enough with pressure cast machines to know if there were differences between these early production and late production machines - i.e., if there were any differences between VIN 7415 and VIN 44650. 44650 is recognized as the last K0 VIN & 44651 is recognized as the 1st K1 VIN. I have owned early K1 numbers, 46xxx and there were very obvious differences throughout the early K1, when compared to a Late Production sandcast. If you are interested, you can get good information from the SOOC website for what is correct for your K0. I would encourage you to study the various website pages, as relates to a Late Production sandcast machine, as well as if you do not own a factory parts manual that references K0 nomenclature, be sure to own one as soon as you can. The factory parts manual is a good starting point to get a general idea of the parts appropriate for a K0 and parts NOT appropriate to a K0.
