In the 70-71 Assembly Manual I recall a reference note suggesting a forthcoming increased cid engine.
Yes, I thought I missed it as well. Guess I'll have to ask Denny Manner next time I see him at a Buick event.
I recall Denny Manner mentioning that as the work on the 455 engine was completed in 1969, Buick Engineering (Powertrain) began exploring ways to get more power out of the 455 engine including increasing the engine size. The reason is that GM was projecting that the full sized models (Electra, etc.) were projected to continue to get bigger and heavier (safety equipment) by some 500 to 1000 pounds. And, Buick Engineering began to experiment with some exotic engine configurations based on the 455 like OHC, multi-carb induction ... and the Stage 2 heads were a part of that program to explore making more power from the 455. It sounds to me that this might be how Denny and others got approval for the Stage 2 program specifically for the S2 heads. Denny also said that some of the experimental engines made some serious power (north of 600HP), but had much more complexity than the S2 head equipped engine which did not require as radical of cam in order to realize some serious power gains from the much freer flowing heads. Of course we know that the oil crisis in 1973 radically changed the direction of he automotive industry as did the tightening EPA emission regs, insurance rates for high HP cars, etc. Many also know of the similar experimental engines Olds was working on at about the same time. Cadillac had already introduced its 500cid V8 as GM usually always gave Cadillac that sort of exclusivity ahead of the other Divisions.
^ Cadillac didn't go to the top of the displacement ladder until '64 and their 429. One year earlier, Pontiac had a 421, Olds' a 394 and Buick a 425, while Cadillac was still at 390. Almost surpassed again in '68 when Olds got their 455, but Caddy went to 472 the same year. Lincoln & Imperial also ran bigger engines until '68 (430 and 440). Cadillac had their 'V-Future' engine program which began in '59 and culminated in the '63 V-12 project, aluminum block & heads, OHC, 3x2, 2x4 and FI set-ups. 6 were built, supposedly well over 400 HP... but I've not seen a displacement on those. That would have been killer.
Yup^^^^^^ like said above i'm pretty sure on top of the EPA issue's, GM management didn't let them out 'cube" Cadillac..
Been a number of years since I heard the story from Dennis, but as I recall it was a 4.312 bore with a 4.500 stroke.. 525.8 inches.. they called it a 525.. at least one was built, and installed into Electra for testing, I believe he told me it was a '72. Now keep in mind, this work might have had nothing to do with more power output.. might actually been more emissions focused.. especially if it was done around 1971.. Dennis told me that what killed the experimental programs ( stage 2 head option for the GS was what they were working on at the time) was the edict from GM that all cars had to run on unleaded 91 octane or lower fuel for 1971... He found this out when he was in Phoenix doing hot weather testing, in the early summer of 1970.. That killed all the performance programs. And caused a scramble to do the re-designs to lower compression ratio's for the 1971 model year, that was just months from production.. Too bad that Buick did not come out with the 400/430 in about 64 or 65... we would have had a lot more factory development before the axe fell on performance. I can picture dual quad rivs in 69/70.. and the stage 2 heads were about a model year short of the sco list.. '71 mid year, or '72 was their goal, I think Dennis told me.. I do believe it was going to be a sco (special car order) "parts in the trunk" type option for racing.. which makes sense, considering the flat top Stage 2 pistons. This also explains why they never cast an iron exhaust manifold for those heads, as it was not designed to be an RPO, but more of a dealer thing, Think more of along the lines of the COPO cars over at Chevrolet.. parts in the trunk, or very limited factory assembly.. All good things to ask him about when you see him at national events.. I usually talked to him more about technical stuff (like why in the world do we have 3 bolts on the top of the 455 valve cover, and only 2 on the bottom?) than I did about the historical stuff.. JW
The 400/430 design criteria had goals for both engine weight and size.. the heads were designed with that in mind. There simply is not room for 3 symmetrical bolts in the lower part of the valve cover rail.. the valve springs are in the way. JW
It seem's like Mr. Manner never gets tired of answering the same questions over and over. He has to be a good man
I guess you could ask why the 455 heads weren't cast for 6 valve cover bolts like the 350s were! Bob H.
Weed is all scaled using the metric system, all measurements are converted. Just look at the scales they use it's all in gram increments. 3.5g =1/8#, 7g=1/4# and so on. Keith
Not that I've got experience in such things, but those would be ounces, not lbs.....And I've never bought or asked for an 1/8 or 1/4 kilo of weed.......
