The Canadian built 261 motors that were installed in the passenger cars, to my knowledge, all used the by pass style oil filter but you never know, nothing is ever absolute. Both of my 59 Canadian blocks are bypass. I also understand, although I have not seen one myself, that the Canadian built 261 pass car motors did use an 848 head, not the more common 261 heads. The Canadian Pontiac 261 Pass motors also used a valve cover that was identical to the later 235 chevy valve cover, but no script. I have one of those valve covers if anyone is interested in seeing one and would be willing to post a photo for me.
With a full flow block, it would appear that you have a later 261 truck block but really the proof is in the pudding. You will need to get the casting numbers, date and as above, really the only fool proof way is to pull the head and look for the steam vents and measure the bore.
Last edited by Dragsix; 11/07/2018 4:37 PM.
