I have an engine in my 68 Mustang with a block stamp of C8AE-6015-B is there a way to tell if it's a 289 or 302. According to my research it is most likely if stock a 289, but other sites say it may be a 302. Can it be verified on the crank by simply dropping the oil pan as one site describes? 1M 289, 2M 302. Any easier way to tell. The intake and carb are both aftermarket so now help there from what I can tell.

 

From what I've read, that date code points to it being a 302 block, but used in a 289 because of a shortage of 289 blocks, so 302 block with 289 internals. On my 65, 289 is stamped on the heads under the valve covers, maybe check there? Doesn't prove anything but it's a start.

 

Don't mess with the oil pan. Pull out a spark plug, get a calibrated rod, measuring scale, or the like, and using a socket wrench on the front of the crankshaft, turn it with scale held down against piston top through plug hole. Measure distance piston travels from BOTTOM TO TOP,

289 stroke is 2-7/8 inches, 302 is 3.00 inches. You should easily be able to determine engine size this way.

 

is there an actual difference in the block other than a code that may have stated it was intended for 302? Isn't the difference made up by the crank and rods alone?

 

Pretty much, you only get a different block when you get into the late model roller stuff.