im currently working on a 1965 ford 3/4ton stepside shortbed ,with 3 on the tree. not sure what motor is in it i was told it was a 240cu.in. but they also used the 300cu.in. also, how do you tell the difference? do they use the same harmonic balancer or fly wheel ? because this one has a vibration some what mild but steady ,motor was overhauled not long ago but thats not to say if it had the right balancer to begin with does anybody know what parts they share or can be interchanged without problems?

 

My understanding is that most parts are interchangable with exceptions starting in latter years with the EFIs. Read the thread lower down comparing 240 vs 300 heads. Someone has listed thier respective strokes.

 

Hello Kelly, and welcome to the forums.
The differences between the 240 and 300 are very few, and besides possibly cross referencing some casting numbers, you can't identify a 240 vs. a 300 from the outside. The differences are in the crank shaft and connecting rods to make a different stroke, and the 240 had smaller chambers in the head to bring the compression up.

Otherwise, same everything. Block, harmonic balancer, flywheel, intake/exhaust, carb, ignition, etc. etc.

If you want to find out the difference, you can measure the stroke. Get something sturdy like a drinking straw or chopstick (I find something like a screwdriver too hard and can damage threads if it accidentally gets jammed) and stick it down a spark plug hole so that it rests on the piston. Then, rotate the engine until it drops to the lowest point, and then mark your stick. Now, rotate the engine until it rises up to the highest point and mark it again.

3.18" = 240
3.98" = 300

 

240 and 300 dampers both have the same amount of imbalance.

none

I would look elsewhere for the vibration issue.