Question, what octane level are people running in their stock Y`s?

Mine has a dieseling effect when you power brake and try to rev a little but when going down the road and flooring it it diesels for a split second almost cant even notice it and then it gone.

Im wondering if the 87 octane regular I am running is just not up to par.

Either that or I need to back timing off some but I never had a too advance engine act like this one is so I am wary if this is the cause.

Only other option I could think of is maybe carbon build up from running the engine at idle over the years till I got to this point.

Anyways just curious what other people are running octane wise.  Might need to upgrade to middle grade on this old engine as that is 89 octane around here.


1956 Ford Fairlane Town Sedan - 292 Y8 - Ford-O-Matic - 155,000 mi