When the kids get a year or so of learning to drive the car I want to swap to a six. What can I do now so I dont have to do it over then. stuff like what size fuel line A six should need a larger line than a four and bigger will not hurt a four. What about oil cooler how big? Anything else you can think of to do now? Pluss that gives me time to slowly get the stuff and not hurt the pocket book so bad.

The fuel lines in a stock 4 and a stock 6 are the same ID. Only the fuel pumps are different.

You shouldn't need to change your fuel lines, unless you have reason to believe on of them is suspect.

-Rusty

I am changing fuel lines to a stainless hard line from the 8 Gal. fuel cell going in the front trunk back. What dia. line should I run?

run -6 AN line, flexible and easy to snake up the tunnel or heater tubes

before you buy that 8 gal. cell.....
consider a larger one.

-especially if you might end up with a -6
-especially if it might be a larger displacement -6
-especially if you might have 2 drivers someday or want to run more than 20 minutes at a time
-especially if you don't have a fuel accumulator system and want to pick up more than 3/4 of the tanks fuel in the turns
-especially if you don't run an accumulator and ever decide to go with a FI engine....

On the oil cooler side, I'd go with -12 oil lines if you ever want to go to a -6 in the future...
I think the rule of thumb is -12 up to a point and -16 lines for the really big motors (3.6L)

b