Honestly the opening question in this post is about equal to why are tires round... All I.C.E. burn paint..
So, does this 66cc combustion chamber promote/increase flow rate? Does it promote/increase swirl effect? Your answer doesn't help me understand this head design. Sorry. I don't understand why Buick has such a small cc combustion chamber when you look at a Chevy 454, their combustion chambers are huge 118 cc's. Both are Big Blocks!! Why is that??? Anybody know??
No it's not. Why would you cloud my question here? You did not get my question. Other folks here got it as i read their replies. I am from across the pond, my native is Dutch.
I'm neither a head designer nor a knowledgeable engine builder but I do know most Chevy motors have flat top-ish pistons while Buick pistons are dished from the factory. Even the highest compression factory pistons have some dish to them. Where a Chevy head may have more volume, its piston has less. So, as long as the volume before compression and the volume after compression is the same ration, say 10:1, it is just a design feature. Where a Chrysler hemi has a hemispherical combustion chamber, the Buick looks like they went for the semi-hemipherical piston top. As for the Buick exhaust port, I'm going to guess it was a machining compromise. Basically, a Buick head as cast, appears to have been chucked up onto milling machines and decked flat 90° apart on 3 sides, intake, block and exhaust. It was likely a lot cheaper to design the port to be flush on the exhaust side with the edge of the block than to perform a more precise Stage 2 machine operation where you can't cut too deep or your ruin the head. Blame the bean counters!
Please DONT I myself like curious questions, inquisitive ones! The Chevy big block has piston DOMES, our Buicks have a dish. Plus the Chevy big block head has a Hemi sort of head, the valves are canted verses our Buicks are inline. The Chevy big block has more valve train issues due to the quirky angles of the valves and related hardware. Every engine design is a trade off, Buick went for torque, Chevy went for horsepower.
Thanks Mark. does explain a lot. There are still mysteries I don't understand. Please bear with my comments & questions. When I built my 327 SBC, I installed TRW dome pistons 11 1/4 CR (identical) to what the Corvette 365 HP engine used. The small block heads were 64cc, stock combustion chambers and this engine used DOMES pistons. These small block heads are only 2cc's smaller than our 455 Stage 1 heads. This is just mind blowing to me. The other issue I don't understand, Buick 455 pistons sit down in the hole about .045 plus, when you add the head gasket in, it's even deeper. Makes me wonder how Buick engine make HP & high torque with this design, and how is it possible you get a Clench band from a dished piston??? I know there are aftermarket pistons that can give you a clench band once you get the pistons to zero deck. But that's today's Technology, not 1970, which is what I mostly have in my 455. To bring a little more HP to my engine, do I have to: (1) go with a different piston design with a wrist pin location that can give me zero deck? (2) Do I need a longer rod to get to zero deck? I would love to understand Buicks head design, where Mr. Manners when you need him lol. Please clue me in. Thanks VET
Maybe read through this publication to see what the designers had in mind, https://www.v8buick.com/index.php?threads/original-sae-conference-bb-handout-booklet-scan.218560/
Well I’m no expert I’m just going to repeat what what I was told. Buick head design 350/400/430/455 is a high velocity head, meaning the intake charge has much speed to it, this is due to the tall narrow intake ports, I’m sure there is much more to it. This makes sense when Buick people say “Buicks like a larger carb (CFM) than a comparable sized engine as the intake velocity is quite fast and is able to operate a larger CFM carb without issue. Case in point, I had my mind set on an 850 CFM carb for my 350, I knew it would run fine, and I wanted some “extra” plus I go against convention, LOL When I called Summit just for kicks to see what they recommended, they suggested a 600 or 650 CFM according to their formulas, I told the guy “ I’m looking at an 850 CFM for my 350 Buick, “OH THATS WAY TO BIG” he says, LOL. I bought the 850 AED double pumper, works great! Hell the Q Jet is rated 750 stock, I just couldn’t get rid of a bog when slamming to WOT from a stand still or a slow roll with my single plane SP3. That’s another thing, people say a single plane will kill your low end torque, my SP3 didn’t hurt it at all, my 60’ at the track stayed the same, no difference, again it goes back to Buicks head design, high velocity.
I'm not understanding the question at all. Specifically what old V8's are you referring to? How could you get from the exhaust valve to the exhaust manifold or header without the port being inside the head. As mentioned, all the engines of the time were similar. Unless you are talking about flat head engines where the exhaust port ran through the block. The valves were in the block. Overhead valves have the exhaust port in the head.
Read Jim Weise's comments about the 470 from June of 2009, As you mentioned, this spring I had a custom piston made up for me by Diamond racing. I have to thank Mike Phillips at AMP for getting me in contact with Diamond, as well as his input on the development of these new parts. It was something he had wanted to do for a while now, and luckily I had the projects in the hopper to order 5 sets of these, so they assigned a part number to them, and could sell them to me for the same price as a "shelf stock" piston. This allows me to retail them for the same price as other high quality Buick 455 pistons. The dilemma we have faced for many years is excessive decking to run a zero deck clearance, with the readily available pistons. It was not at all uncommon to have to cut .050 off the deck, to get that zero deck. And zero deck is very important, for engine efficiency and power, as well as detonation control. And when you do that, you have to cut the intake side of the heads to align the intake again.. it all adds up, as milling is not inexpensive. It ends up being lot of wasted motion, and although I will confess it might not be a big deal, but taking more material off an already weak block, simply can't be advantageous. The next thing to deal with is rods.. While stock rods are fine for up to about 500 HP in a street application, the advent and widespread use of Aluminum heads these days has made that once rather elusive mark, for a street engine, to be a rather easy goal. So we are now really working the stock rods, and after ARP bolts, re-size and an often tough balance job, you end up with around $300 in a set of stockers.. That's if you have a set of 8 that can be re-done and balanced.. That not being the case was so common, I typically bring in 10 stock rods to get 8 good ones, and that's after I have picked thru my cores to throw out the obviously poorly machined or cast ones. I would be remiss not to mention the TA Sportsman rod here.. That's really a great quality rod, no doubt, I have used many, many sets. It's certainly the easy rod for a "drop in" replacement, for you guys having machine work done at maybe a less than "savvy" machine shop. I will get to that later. But being a drop in replacement, it has to work with available Buick pistons, in both the pin diameter and compression distance, so we are now back to the massive decking issues. Recently, Wiseco came out with a new Buick piston. Several builders were going to Pontiac Rods from Cat, and modifying them for Buick use. Some were going to the H Beam BBC rod from Eagle Specialty products down in Miss.. That Eagle rod is a great value, plenty strong up to 700 HP, and it's a good quality piece. These builders were using a 6.635 long Cat Pont or Eagle BBC rod and turning the crank down to fit it, and/or narrowing the rods. Also on both rods, the pin end had to be opened up for the 1" Buick pin, that the Wiseco pistons have. The drawback here is twofold.. Extra machine work on the rods to fit the Buick crank for the pont stuff, or on the crank for the BBC stuff. As well as the pin end machining on both rods. More of a problem is that you really do have to surface the block at least .020 to clean it up completely. Most of the Wiseco/Cat/Eagle combos require a 10.560 deck height, which only gives you maybe .010 to clean up the decks. I have seen a few cases where that's not enough. Beyond that, that Wiseco piston is not a quite piece during cold engine operation. Trust me, if you put them in at the recommended .005 clearance, you will swear the thing has a rod knock when it's cold. Especially on the milder cam/iron exhaust manifold stuff. Been there, done that. One we did this last fall was so bad, I wouldn't let it leave the shop, and ended up replacing the shortblock, as it turned out, with the TA/SRP pistoned shortblock that we originally built for you John.. I thought a better option was to have a new piston created. We use the Eagle rod, but having the ability to do it now with the custom piston, we went with a 6.800 length. The longer rod is easier on the cylinder walls, which is a big plus when your working with the rather thin wall thicknesses that most of our Buick blocks have. In addition to that, we had the piston designed for a 10.550 deck height, a .050 offset grind on the crank, and offset the pins for quiet cold operation, even with the superior 2618 material. And we specified them to be built with the .990 pin dia, so that eliminates any work required to the rods, beyond the normal pin fit. The key to the combo is having access to a good crank man, and I am blessed with having one of the best in the business at my disposal. The rod pins are offset ground .050 to fit the stock size BBC big end, and use the infinitely available BBC rod bearing. Want .001 under bearings.. no problem.. hard bearings, soft bearings, dowel end bearings.. you name it. Easy and cheap.. I chuckled at my cost for a set of ACL BBC rod bearings.. it was about $25 less than the Buick bearings.. But back to the crank.. To fit the rods, beyond the offset grind down the the 2.200 inch size, the rod pin on the crank has to be widened to 1.995 to accommodate the wider BBC rod bearing, and allow for a nice .015 side clearance, and you can just get there with the stock Buick crank. But the key here in widening is having a good crank man that dresses his grinding wheel properly, to not burn the crap out of the cheeks, and produce a nice finish. Not every grinder is capable of this, or maybe more correctly stated that they will not take the time and effort to do it right. The advantages of this combo are: More cubes from the longer stroke Better rod ratio with the longer rods Easier on the cylinder walls Lighter pistons and pins Offset pins for quiet cold operation, even with the better 2618 piston alloy. Drop in fit for a $450 set of 700+HP H-beam rods No excessive decking or intake fit problems, but enough room for complete deck cleanup. Wider rod bearings to better handle the loads A huge choice of rod bearing types. Along with easy availabity and lower cost. And of course they have the performance oriented 1/16 compression rings. All this adds up to a stronger engine, for a very attractive price. I use a P bearing with a smaller rod journal radius on motors up to 650HP, as they work fine, and don't require surface hardening of the crankshaft. This keeps the costs down. On motors beyond 650 HP, we go to the H series bearings, which allow a bigger radius on the rod journals, and then we nitride the crank to harden it for the H type bearing. This is all done in preparation for the future. We are going to need a strong rod with wider bearings to handle the loads. Our BBB street/race motor future lies directly with that TA Tomahawk block. Power output on these street motors will be impressive, and I already have a development block on order, to build multiple combinations for killer street strip motors.. I truly believe that 650-700+ Street friendly Naturally aspirated HP is on our near future.. and with forced induction.. well then your pocketbook is the limit, not the parts.. Stay tuned.." Now we have drop in forged rods. We don't need to use the Eagle Chevy rods, or Pontiac rods.
When you look at a 454ci head those exhaust passages coming from the head are much less "projected". That "burn off" part seems less of an issue there.
I think I’m better understanding your question now. Are you referring to the “as cast” exhaust ports that extends outward from the actual side surface of the head where the exhaust valve is located?
What you have failed to notice ( hard without having both in front of you ) is that a big block Chevy head due to its massive Bore and Bore spacing is almost 2 inchs wider then a Buick head( and many others !) yet the width of the top side of this motor still had to fit into the size engine bay ( A, B, F body) as all the other GM motors . So this means that if the BBC head was cast with Buick lenght Exh ports it would be at least another 2 inches wider and never work for passenger car usage. BBC heads are as wide as Buick Nail heads, just for comparison. On the other side of the coin is the Ford heads for the FE motors. These heads are so narrow that the push Rods pass thru the Intake Manifold! If you have never had the flat out back breaking joy of removing one of these massive cast iron intakes off a FE motor while it's still in a engine bay then you still have many new curse words to add to your vocabulary!
Give him a break..for *****sake! He is simply"" asking"" why do the Buick 400 430 455 heads have extended exhaust ports? Maby he didn't explain it proper in the first post. Yet you continue to jump on him saying he should design the heads then after all was clarified.
