And even the block designation could be misleading because over 30+ years who knows what could have been done to the engine. The heads could have been replaced or something. Bottom line is, there is NO WAY to determine if you have "Big Valve/Stage 1" heads without pulling them and looking at them. Engineers would just pull 455 heads off the line and fit the big valves into them. There were no special castings or markings denoting Stage 1 or big valve heads.
Oh, and IMHO, big valve heads are Stage 1 heads. Swirl polished or not, if you can't fit a dime between the valves, I call it Stage 1.
Usually, if the engine is original, if you see the large mouth air cleaner, it will have the larger valves (seems to be most of the time). If it has the old pixie-straw air cleaner housing, it's probably standard valves. Stage 1 was a package deal, but it shouldn't be considered incorrect to say Stage 1 heads. To say the engine itself is a Stage 1, it would have the Stage 1 package - slightly higher compression pistons, different cam, different valves (same size), etc. Engine numbers and VINs aren't always reliable, because for a liitle extra dough, you could get the dealers to do just about anything you wanted to the engine.
My Father's 72 Riv came with a chrome air cleaner cover, 455-4 sticker, and chrome valve covers from the dealership. He didn't ask for it, they just wanted to get rid of the car as the 73 models were rolling into the showroom. As far as I'm concerned, that engine was showroom stock! :bglasses:
Large snorkel air cleaner was standard on 71 Big block full size Buicks. Unfortunately, it's not a good way to tell if the car has big valve heads or not.
Maybe, Maybe not... I've seen intake valves that were so gunked up after a few thousand miles that it didn't matter if they had swirls. I kinda expected to see that on the exhaust valves only...but live and learn. Lots of factors cause this, leaking valve stem seals, lopey idle mixed with slow driving, etc.. I don't think anyone will admit to driving slow, but most like (the sound of) lopey idles...
Same here, my daily driver Stage 1 came with the SF code stamped on the block. The Vin is stamped correct as is the BB trans.
The 455 motor i rebuilt for my car was out of a 74 Le sabre and also had the big valve heads. I dont think they do much on a stock rebuilt engine anyway so i didnt get to excited about it. ED
Large snorkle air cleaner is just one of those "typical" indicators. I wouldn't bet a paycheck on it, but it seems to hold a little water. The ONLY way to know for sure is to pull the heads. At the same time, while people can get really excited for the Stage 1, or Large Vavle Heads, or whatever anyone calls them, there's nothing wrong with the standard heads. It isn't until you get to more significant buildups that it starts making a bigger difference. A typical street engine will only vary a few horsepower (maybe 5-10) between the heads and you can get that through other means. In a stock build, the standard heads actually provide better low end response for everyday driving. The larger valves are definitely better for higher horsepower applications, but for a typical street driver they're just not going to shave a chunk of time off your 1/4 mile run.
Cool Service Bulletin, I am going to have to go snoop around under the hood of the '71 Estate Wagon, Since we are talking about big cars :Brow:
