BB Mopar head design ??

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MopaR&D

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After taking apart a few big-blocks (383 and now 440) one peculiar thing I've always noticed about these engines is the valve location and angle. Why do they sit towards the outside of the block instead of closer to the center? The factory reliefs in the chambers and some of the block decks to keep the valves unshrouded just makes me curious what was the purpose? I read an article in a recent issue of Engine Masters magazine where a company building a low-deck 466" stroker heavily modified the heads (Procomp aluminums here) to improve flow; besides lots of porting they angle-milled the sh*t out of them then relocated the head bolt holes to move the heads "upward" towards the center of the block. Maybe a 'dyno queen' motor to some but made 755 HP at 6300 rpm and 674 lb-ft at 4800 rpm.

If you're curious for details google "engine masters rram mopar" or something similar lol
 
In 1957 the priority was an engine that was economical to produce and expandable to larger displacements in the future. The heads did get a performance redesign in 1964, and the 426 Hemi was born.
 
In 1957 the priority was an engine that was economical to produce and expandable to larger displacements in the future. The heads did get a performance redesign in 1964, and the 426 Hemi was born.

OK but the wedge engines continued on with multiple updates throughout the '60s including head redesigns (516, 915, 906, 346 etc.) for bigger valves... would it have been that hard to tweak the design of the heads a bit to move the valves toward the center of the bore?

Another question how much of an effect does it actually have, as in would the gains be only worthwhile in a racing engine or would it work on a street engine too?
 
Every design is a compromise of one sort or another. Changing the heads much would have meant a redesign of the intake and exhaust (expensive). Rocker arm length, pushrod angle, etc. might be more difficult to get right. The original design easily made enough horsepower to be competitive through the production life of the motor.
 
Open up the wallet and let the cash flow....get a set of Predator heads....On a big wedge there is someone in Florida that is getting over 1100 N/A ponies on them...no spray neither.....on pump gas.....
 
Every design is a compromise of one sort or another. Changing the heads much would have meant a redesign of the intake and exhaust (expensive). Rocker arm length, pushrod angle, etc. might be more difficult to get right. The original design easily made enough horsepower to be competitive through the production life of the motor.

So then was it a geometry issue with the valvetrain or something? Still trying to understand why they put the valves where they did when they first design the engine; moving them in would even have had the benefit of making the engines slightly more compact on the outside. I can't think of any good reason to move the valves away from the center of the bore except for some kind of interference with other parts in the engine.
 
A lot of what we know now about heads was learned after those were designed. There are likely a geometry issue, but most heads have short exhaust port and long intake ports, especially wedge heads. Poly (include BB Chev and Ford Cleveland) and hemi heads are a better design as far as flow potential, but they are considerably more expensive to produce.
 
-Also gotto remember, they MOLD these heads from cast iron, which would have had the tool and die department redesigning a whole new "slug" to be milled down to specs unknown so that in itself would have been a real costly job within the confines of that, the rocker shafts would have to be changed to fit, as well as the rockers themself. As well as pus rod issues could have occurred, so then you move one thing, and the rest has to be made in adjustment of that one design change. And as said, the angle the head meets the intake, what may have that been like if they had moved the location of the valves?

Having said that, man hours! What they did, was use what they had, in an effort to keep the cost down to a minimum, BUT have the utmost use overall...Plus, what was the chamber like? you move the valve inward more center of the head, what was the cast iron meat like nearest the intake? What was the oil passages like if this had been done? what was the rod openings been like to work with? A LOT of openings for oil, rods, and valves, and even the spark plugs could have been effected by location....Remember also back then, they didn't have the technology we have today as far as CAD and what it can do these days.....

A LOT goes on, on a "drawing board" when your working with something like this....
 
The first real issue here is that your questioning the engineers.
They were given a task to complete under restrictions and guide lines. A high performance head was not the guide line.

What ever YOU can come up with or what ever design you "THINK!" is a good one now will only be a laughing stock of a joke 35 years from now. Don't even consider what will it will be thought of 47 years from now.
 
Good read. Though it doesn't address what the engineers were trying to do under the constraints they were given. Clearly adding a larger valve to a head improved performance. As stated in the article, flow suffers in most cases above 400/450 minus a named head that did well a bit further up in the lift range.

When these heads are flow tested, getting above a low 200 was great in there as cast form. After head porters investigated the heads of all years, even the smog heads showed promise. But that is after the fact and not what had to be self with at the factory front.

Basic instuctions to the engineers were something like, "Find us more performance in what we all ready have without major changes." That would mean no new casting for the sake of performance. And even when they did change a casting, it was not to radical at all. In fact, I'd call it a minor change.

The bottom line is money. Don't spend it on Chryslers dime.

Consider the year of the first big block. 1957. What was performance then is not performance now. Performance now is race stuff then. The power these engines made back the. We're out of site! Just 15 years earlier, the performance engine (if you can call it that back then) was less than half the power.

Crapping on the engineers work then is a ridiculous thing to do.
 
Crapping on the engineers work then is a ridiculous thing to do.

lol I hope that's not what you think I'm doing here, I'm a mechanical engineer myself and actually took a course on internal combustion engine theory and design. I'm just trying to get inside the minds of the engineers back then and understand the reasons behind it. However it looks like Jim Lusk and 67 Power Wagon gave the best answers so far, I'll take it.

Good article Hemaniac I think I read it before but it gives really good info on the later emissions heads and debunks the myths about them being undesirable (they actually respond better to porting than earlier heads like the 906 and 915). Didn't see any specific mention of the valve location though maybe I missed it...?
 
The engineers were more involved in the design of the 426 hemi head at that time and they weren't worried about increasing the BB heads, they thought they were good enough at the time. Now days we have so many aftermarket heads to choose from its up to your budget I guess.
 
I say while we're at it....Here's a GREAT one to consider, if your "trying" to get in the minds of a MOPAR engineer......

So its the years of OUR famous "Hemi" the 426.......Your designing this from the big wigs saying we want a "lengend"....... the slant 6 crew hears this, so they on their lunch break begin looking atthe slant 6 and going OK WTH? can WE do? NOTHING! Why? Mopar didn't pay for it, BUT taken the info we ALL have.....Transfer it from the COMPLETED 426 V-8, from a Wedge, to a Hemi, and make a 226 Slant 6 WEDGE to a 225 Slant 6 HEMI? WHY?

No call for itm, because we already had the 426, for one, and for 2, they were making the 245 and the 265 in Aussie, BOTH Hemi's (or so they say) BUT, take the Hemispherical combustion chamber, and try to fit that bastard in a 6 cylinder head, or better yet the 225 SLANT 6 head! No less, that be such a nightmare, the angles of the intake valve to the angles of the exhaust valve would be almost ridiculous in the 245 or 265 orientation....THEY could have, done this the "Ball-Stud" way but, really? Then say you got the head to work, WITHOUT modifying the block (say, you just haven't gotten that far yet) SO, then you get to the block....... WITH Ball Stud type set up for a Hemi head, in a slant 6 block, for 6 cylinders, then you got all the rod passages to make work for the push rod to move as needed by the cam.....You get this, BUT HEAVY machine work on that block. At this point, from the drawing board, to the maxchine shop to reality, how many man hours might you *THINK* a task such as that took? REALLY you don't say? Granted, they worked day and night A LOT OF UNPAID nights on the 426, to get that thing to be what it is.....today!

Like Rumble said, back then, what '66? '67? the 440 was the ****. ONLY SECOND to the 426 HEMI! In STOCK form! Granted, the smallest, 383, for say '67, would do the same as the 440, BUT at a MUCH higher RPM. and that for a 383 back then, was pushing that little thing to the limit! The 426 HEMI, on the other hand, was doing it without breaking a sweat. As the 440 was to be the biggest of the "crew" for Mopar but wasn't an easy breather, just Rumble said, they were to busy working their asses off on that 426 Hemi that was a promised performer, and to this day, is a true legend! In its own time!

That motor was doing things not normally seen for its time 50 years ago......Sadly, what engine do we have today thats a legend such as the 426 Hemi or for that matter the 440 Wedge? (I GOT a 383) in my truck, and let me tell ya, If I had to pull it that something happen a piston rod snapped and went through the block, I'd be hunting a 440, WHY? well thats an easy one! There everywhere......This is, if I had the cash in hand to buy another Mopar big block. as I can get a small block 360 just as fast for a bunch less money, BUT lets just say, I just had to keep the block a big block Mopar more specifically a B block 383 (RB 383's are rare!), 440 RB would be the next BEST thing, stock heads an all! Tried and true proven designs, and old as dirt still rompin rubber to the road and leaving a nice blue trail....... gotta be something to be said for that!

DON'T try to beat down the 40 plus years ago, engineers that were our age then, with nothing like we have today for what they did........ WHAT THEY DID.. they DID WELL for the time!
 
OK I get it the Hemi was more important lol. I love big-blocks too btw don't get me wrong I'm having a blast getting my cousin's 440 ready for a top-end rebuild and I can't wait to feel the torque from that thing. I just got wondering about the valve location when I was standing in my garage staring at the combustion chambers in his 346 heads and trying to visualize the flow through them.

One thing's for sure those dang open chambers with the spark plug way at the edge make for some slowww combustion makes sense these need lots of timing and rich A/F ratio to run the strongest. Don't worry I know the reasons behind that though lol
 
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