Cooling the 4.9
My 4.9 conversions are using stock Fiero V6 radiators without any overheating problems. I've heard of a few cases where the cars will overheat when the A/C is being used on extremely hot days. I'll continue to use stock radiators until I have trouble.
The rear engine-to-pipe hoses are fairly simple. On the bottom a stock 4cyl hose is a good fit. On the top I use a 4cyl hose and a short section of the Cadillac hose connected with a Moroso or CSI inline filler neck. I use a 25-30 lb cap on the filler to prevent coolant from blowing out, and a cap or plug on the overflow outlet to prevent air from being drawn in.
All 4.9s were originally equipped with an engine oil cooler. It's probably a good idea to install one on your Fiero. I use PermaCool p/n 691 oil cooler mounted to the front of the cradle using two pieces of 1/8" x 1/2" flat steel. The steel lines on the engine can be cut at any point, and 1/2" hose pushed on and clamped. I use a standard tube flaring tool to put a bulge on the end of the tube for security.
