First Time Building a Pontiac Motor. Need Advice.

Congrats- you got a winner there. I have a 1976, the last year 455, also out of a Grandville. There is not much needed to change. The 455 should have the Pontiac 067 cam. That cam came in 389/400 GTO's but in a 455 it is just a very strong running cam. Low rpm torque and smooth idle is what it does best. Perfect for a land yacht. You have the OEM carb? KEEP IT! That is the best carb for that engine. The stock intake is fine too. How is the compression? Any oil burning? Expensive noises? If OK, don't go overboard. No sense opening a tight engine for no reason. I like to use a Pontiac 301 oil pan, as it has a nice oil baffle inside. Also the early 400's used a full length windage tray. It will bolt to the main caps if the holes are there. A nice Melling 60lb oil pump would a good upgrade. Some people like to drill a .030" hole in the rear oil gallery plug so oil squirts at the distributor gear. Why the heads? What was wrong with the originals? A clean-up and valve job would be nice. If the oil pressure was good, the bearings are probably fine. Replace if the pressure was low. A new water pump, baffles, and seals would be nice too. I guess what I am saying is to replace and upgrade the wear parts, and leave the basic block alone if it is tight.

7M5 would make it a 1972, I have those heads too. The good news is they are the last of the big valve heads. 2.11" intake and 1.77" exhaust. No EGR . Are they missing the end exhaust manifold bolt holes? In 1971 and '72 Pontiac decided to save $.50 per engine leaving those bolts out on many heads. They beveled the manifold to make a single bolt tighten it up. Dumb idea.

Smoke could be rings, or valves. I guess at this point a rebuild is indicated. Perhaps the absolute BIBLE of Pontiac info is these books that H-O racing put out many moons go. They were active chasing power right up until the last Pontiac V-8 left the assembly line. Reprints are available so I would grab one for sure. Here is a short bio: http://pontiacpreservationassociation.org/deceased nominees/ho-racing.html Get these books and you will be golden.

Ignore the racing stuff and learn about Pontiac engine design and theory. A 455 lets the cubes do the talking so a stock 455 is all I would need. The only different cam I would consider was one that provided lots of lift but had very short duration. A 455 makes it's peak torque at very low rpm, so trying to rev high is a waste of time. I have often been bashed for thinking that by what I call '455 snobs'. Unless you invest in forged rods, pistons, better crank shaft, trying to rev high is pointless. These engines were designed to motivate huge land yachts and they do that well. Don't let anyone convince you otherwise. The 1976 Grandville that I pulled my 455 out of would light up the tires in my driveway right from a dead stop. It was totally stock.