The nailhead Buick had one advantage, it was narrower than any other OHV 90 degree V. That is why the early V-6 fit in the old Jeep CJ's and were used in dual engine marine installations. Thermal properties may have not been good, but for the intended low-rpm duty coupled to a Dynaflow transmission, free flowing ports were not a priority.

 

The newer Buick aluminum V8 and the iron V6 that grew from it, while clearly an evolution of the nail head philosophy, didn't have that same, lame, exhaust-all-the-way-across-the-head design. They actually addressed that shortcoming by flattening the chamber and by allowing the exhaust to exit higher on the head and earlier via a much shorter port that exited before the end of the head. (It's really difficult to explain.) Yes, they are all pretty narrow for 90 degree designs. I agree that the intended purpose didn't require a high flow head but what bothers me is all that heat being shed back into the head from those long tortuous exhaust ports. I mostly just wanted to clarify to the other folks on this thread that NOBODY copied the nailhead design.
Regards, Eric

 

I was simply pointing out that the Buick nailhead "Hemi" differed from the Mopar Hemi and Mopar Poly in that it's vales were not opposed to each other, which took away one of the big advantages of the Hemi/Poly design, which was/is it's excellent breathing. You are incorrect about the 4.7 though. It is an OHC engine with rockers but no pushrods and a chamber that looks like the design that debuted in the 50s as the Mopar "Polyhead". Many, many engines, both pushrod and OHC, have through the years employed this "Semi-Hemi" design, too many to mention. The Ford 6.2 is the latest one. Yes, 4v heads have a flat Hemi chamber, you could say that almost everybody is making a "Hemi" these days, but Chrysler of course owns the name cause they trademarked it. So when I'm talking up the Hemi, I'm not so much talking up the Mopar Hemi, as I am talking up all Hemis, including all of the 4 valves, which are indeed better. As for that nailhead, again, nobody has ever copied the Buick nailhead with both of the valves on the intake side of a Hemi chamber. Yes, you could say it was a Hemi, but that's about all you can say for it. And again, it came out 2 years AFTER the original true Hemi.

Couldn't be more wrong here. You must have misinterpreted what Tom Hoover said. Both the old Hemi and the nailhead had a very "domed" Hemi chamber whereas the new Hemi chamber is flatter, much like a modern 4 valve. But other than that one change (well there's that dual plug business too but even that can be traced back to the 2nd generation race Hemis of the early 70s), the new Hemi is old Hemi all the way, right down to the double rocker shafts, which is yet another thing you won't find on the Buick. There's more to being a Hemi than just the chamber design although that is of course where the name comes from. Again, there is not one feature or design element in the new Hemi head design that can be attributed to the old Buick nailhead. Not one. The nailhead was a cheap, substandard copy of the original Hemi, plain and simple. It technically had the chamber, but nothing more. And it was the old, severely domed style hemi, just like the original Hemi, not the flatter new style we have now. The new Hemi is a new, improved copy of the original Hemi, plain and simple.

If you lived that close to Tom Hoover, and were so influenced by him, how come he didn't make you into a Mopar man?

I seem to remember though that "TV Tommy" had to combine two or four of them into one car to go fast!
Regards, Eric

 

Take a few minutes to researchs Tom's input into the 'new' hemi. The reason it is a pentroof (the correct geometrical term for it) is due to squish area and chamber volume. A true hemi, while breathing better, cannot make emnissions. The buick pentroof, to those that have seen them were not domed at all (part of the definition of being a 'pent' roof).

Of course, why take words for it. you can always look here: The new Dodge Hemi V8 engine in full detail - 5.7, SRT8 6.1, and 392 6.4 and scroll to the picture of the combustion chamber.

the shape of the chamber is unmistakeably pentroofed

 

OK, so is it the quench that you are fixated with? The Buick nailhead was not the first engine to use quench but I will grant you it may have been the first "Hemi" type chambered engine to use quench. OK? But even those quench pads are located differently in the new Hemi with the quench pads running along the sides of the chamber on both sides of the valves as opposed to the nailhead's pads which are on each end of the chamber. And the Buick nailhead's quench pads are so small they are hardly worth mentioning! The Boss 429 was another "Hemi" type engine that used quench as well and I am sure that there were/are others. None of this hardly qualifies as anybody "copying" the nailhead.

And again, for the record, I'm not saying the Buick nailhead breaths poorly because of any thing to do with it's chamber, I'm saying it breaths poorly because of it's poor valve locations and poor port locations/port layouts/port designs as well as the fact that putting both valves on the same side of the chamber forced the valves to be too small hence the name: "Nailhead" because the valve heads resemble the head of a nail.

Also, for the record, the engine that replaced the nailhead, the Buick 400/430/455, is a pretty decent design. It is in fact my favorite GM big block!

Now, lets look at a cutaway of the nailhead:
http://image.carcraft.com/f/9579816/...mage_large.jpg
and the first gen Hemi:
http://image.carcraft.com/f/9778400/...power_hemi.jpg
and the second gen Hemi:
http://image.carcraft.com/f/9778406/...4_426_hemi.jpg
and the third gen Hemi:
http://image.carcraft.com/f/9778412/..._5.7l_hemi.jpg

Like they say, a picture is worth a thousand words! So, four pictures should be worth four thousand words!
That Buick chamber sure looks domed to me! It's by far the most domed chamber there! Even more than the original Hemi!
Do you see the progression AWAY from the steep domed design of the both the original Hemi and the nailhead Buick? Again: There are NO uniquely Buick nailhead design features in ANY Hemi or ANY 4.7 Mopar or ANY Poly head Mopar or ANY other Mopar or ANY other engine!

You want reading material? Here is some reading material: New DaimlerChrysler Hemi Engine - Car Craft Magazine and: Pontiac Firebird - Car Craft Magazine and: Buick Nailhead - History Of - Car Craft Magazine
BTW, one of those articles was listed as a source in that Allpar article you linked.
Regards, Eric

 

I guess Im just gonna have to allow you to continue to believe what you believe since you apparently cannot come to grasp with what makes a roof 'pent'.

(if you really wanted to show a 'modern' 4v domed chamber you would have shown a olds quad 4)

 

You could do the same thing you know. Go ahead and post it. But what does the quad 4 have to do with your assertion that there are Buick nailhead design features in the new Hemi? My focus was to show that, contrary to what you would have us believe, the new Hemi moved AWAY from the chamber shape of the nailhead, not towards it. Yes, the quad 4's chamber, just like most all of the other decent modern 4 valves out there, is closer to what the new Hemi was/is trying to emulate. You would have had a better chance if you had started out with that argument instead of the nailhead one. Maybe that's why you are bringing it up now....

For the record though, the quad 4's chamber broke no new ground. There were already plenty of nice, well designed, compact chambered 4 valve heads out there when the quad 4 debuted.

You can call these chambers by whatever names you want to. It doesn't matter. Look at the pictures again and post one of the quad 4 too. The new Hemi has VERY LITTLE resemblance to the nailhead.

BTW, since you like throwing names around, "Hemi" is short for "Hemisphere" which means "half of a sphere". The original Hemi's chamber was a true "half of a sphere" while the new Hemi and the modern 4 valves have had their "spheres" squashed somewhat.
Regards, Eric

 

Getting back on topic, I was at the U-Pull-It today getting a fuel injection "spider" for my "CPI" equipped 95 Blazer. All of the Blazers and Jimmys and S10s and S15s and Sonomas etc. etc. and so on, ALWAYS have their spiders removed. It seems like they are gone even before they even hit the ground. But I've discovered that the CPI 4.3 was also an option in the Astro minivan and it's GMC equivalent so I've been on the hunt in the minivan section too. Unfortunately, I'm not the only one who knows CPIs can be found there so the pickings have been pretty slim there too. But today was my lucky day and I found one! Anyway, while I was toiling away inside the Astro getting my Spider, I saw the Astro's owner's manual there. On the cover it claimed "The longest lasting trucks on the road". Now we know that back in the mid-90s when this Astro was made Chevy was still claiming that title but they were apparently also including minivans in their figures. Were all the manufacturers factoring their minivans into their figures? Were they all taking the R.L. Polk registration stats for both trucks and minivans and lumping them together to skew the results? I've always thought of minivans as throwaway vehicles but if you think about it most of them live pretty easy lives, not towing too much, not carrying loads that are too terribly heavy, usually being driven by the least aggressive driver of the family (Neither the teenage kids nor the Dad want to be seen in it), I'm pretty sure Chevy and I know Mopar have sold and continue to sell more minivans than Ford does, maybe this is how they've been skewing the results!
Regards, Eric

 

I know Chevy full size van is a very reliable and long lasting,hard working vehicles,but,what about a Chevy minivan,I have one,2002 Chevy Venture,3.4L.Is it reliable van or not?

 

I don't know, you tell us! You are the one who has one!

What I am saying is most minivans live pretty easy lives, not towing too much, not carrying loads that are too terribly heavy, usually being driven by the least aggressive driver of the family (Neither the teenage kids nor the Dad want to be seen in it), which may mean they live fairly long lives since they aren't being worked too hard or beaten to death. This would help a manufacturer pump up it's longevity stats. Just a crazy theory on my part but I can't think of any other reason why the manufacturers would include the minivans in their stats.
Regards, Eric

 

You are right, I could have. But I worried it would do no good, so I didnt. You see, when you keep posting pictures of heads that are clearly, to the naked eye 'pent' roofed (again, lookup what makes a 'roof' or chamber pent or not) yet calling them 'hemi', I feel there is no point.

As I said, I could care less where the valves actually were as they were irrelevant to chamber shape. the Q4 engine however, was a different animal in that it was not 'hemi' by purist definition, but it was not 'pent' at all and any competent picture of one might 'learn ya a little'.

Your argument reads as thus: "I have a sphere here, but to get it in my locker I smashed it on all sides, but its still a sphere - see?"

 

I dunno man, my mom is a lot harder on the go pedal than my dad or me.

 

Yes, for once you are right. There is no point. And you are off topic again too. Again, call the chamber shape what you want, there are varying degrees of "pent" and there are varying degrees of "hemi" shape. It doesn't matter what they actually are, the point is the nailhead's and the old Hemi's chambers more closely resemble each other while the new Hemi has moved away from that shape and now more closely resembles what a typical modern 4 valve chamber.looks like. While it is true that the new Hemi's chamber is squashed so flat now it really isn't a "Hemi" anymore, it still doesn't matter if it's "Hemi" or "pent", because your argument was that the new Hemi has nailhead design elements and I have proved that argument wrong. Now you want to argue as to whether these are "pent roof" chambers or or "Hemi chambers? It doesn't matter because whatever they are, whether they are viewed from the bottom, from the side, or from the front, they are not Buick nailhead chambers! BTW, "Hemi" refers to the chamber shape as viewed from the front (or back), not from the bottom. Car Craft is on record as approving continuing to call the new Hemi a "Hemi" despite it's newer, superior, squashed shape.

Like I said, post it! I guarantee you it's chamber looks just like the "new" "Hemi".

No, I'm not claiming that. I just claimed that there is NO Buick nailhead DNA in the new Hemi or old Hemi or ANY OTHER ENGINE.
Regards, Eric

 

LOL! Your Mom sounds cool!
Regards, Eric

 

In my book, the Astro is a small truck, while the true minivans are car-based. Remember the VW bus and Dodge Caravan were both car-based. I have seen more exploding automatic transaxles in vans than passenger cars due to the increased weight, not driving style.

The dividing line for R. L. Polk may be if it is registered "commercial". In that case, a cargo van would be a truck, while a passenger van would not. Example, Ford E-series, commercial cargo van or Club Wagon. One is a truck, the other a passenger vehicle. The numbers of these things is probably too small to skew results compared to pickup trucks.