Quote Originally Posted by f2offroad
hello i have a couple questions for you. my name is ben i own a 85 olds with a 3.8l and im putting in a 455. i see the mounts from a 307 will work in the stock location.what raditor did you use . is the 307 enough to cool the 455 or do u have to use one for a 350 diesal engine. also what front springs did you use to handel the extra weight. i appreciate your time
I used an F-body aluminum radiator with Water Wetter and Distilled Water (important, don't use tap water). I also added some coolent to keep from running too cold and freezing in the winter. The instructions tell you the right combination.

Changing the front springs is really not necessary, especially if you are going from a 307 to a 455.
Measure the ride height before and after and see how it handles, that's always a good starting point.

A 455 with an aluminum intake weighs 625lbs or 660lbs with an iron intake vs a 307 which is around 600lbs since it has an aluminum intake.
A 350 with an iron intake weighs about 635lbs.

The V6 weighs about 125lbs less than the 307 so if you added a 455 with an aluminum intake you are looking at a 150lbs inrease in weight.

The additional weight is almost negligible but the additional weight of the 455 can easily accounted for if you are really concerned.

On my 84 Cutlass I added an aluminum intake, removed all the A/C (-35lbs est.), ECM components (-15lbs), have an Aluminum hood(-30lbs came stock) and core support (-12lbs), Aluminum water pump -(3lbs?), aluminum bumper (-17lbs came stock), hollow 36mm sway bar (-8lbs), aluminum rad. (-3lbs est.) and am still running stock springs.
With the 455 installed I'm running at least an estimated 45-50lbs or more under what my car came stock with and the ride height hasn't changed.
My 88 Cutlass on the other hand is loaded to the gills on the front with an iron intake 455, A/C, heavy fiberglass W-25 hood and a 4 row radiator. The previous owner installed too stiff of a spring to try and compensate for the additional weight, and they have worn the front shocks out making vibration when you go over a pothole/cover or tracks. It's nothing of major concern since I don't drive it much but I plan on redoing the whole front end on that car in the future.

If you remove the A/C Compressor and ECM components, add and aluminum intake and relocate the battery to the trunk right there you should have solved your weight issue.