Engine swap 318 to 360
The van is a 76'
So if I do have the 904 I can keep the 318 torque converter and just need a flex plate?
Yep! I'll add a link below for the flex plate to do just that.
@Locomotion posted a pic above that shows what the pan gaskets look like on 727's and 904's. Open your hood and look down to where the trans dip stick tube goes into the transmission. If that front passenger side corner of the trans is square, it's a 904. If it has a kick out in that corner, like the pic of the 727 pan gasket above, it's a 727. There is a B&M flex plate available either way. The one in the link below is for 360 to 904. Whichever one you get, hold it up to your torque converter like it will bolt up to the motor. B&M flex plates are marked 'Engine side'. Make all 4 flex plate to converter bolts line up and then mark both the flex plate and converter at
one bolt hole. Line that one up first when you go to bolting them together in the car. If you don't do that step, you will make up new cuss words when you keep moving it to get it to line up....and it does it the 3rd time you move it....lol
All of your engine accessories will bolt back right where they were on the 318 and line up just like they did before. If the Dart has an electronic distributer, compare it to the one in the 360. If the plugs on the wires look the same, just use the 360 distributer instead of swapping them.
The things you will really need to mess with will be swapping the oil pan to a 360 car pan and pickup. Buy a new oil pump pickup with the pan. It ain't worth the trouble to pull the pan off the 318 to get that one when a new one is cheap. You will also need to get the throttle pressure (kickdown) linkage set correctly when you get your carb choice made. If you don't, your transmission won't live long.
It's great you're researching before diving in turning wrenches. Keep asking questions if you have them. :)
B&M Flexplate