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Holden six cylinder head 101.


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#1 _Bomber Watson_

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Posted 25 December 2013 - 10:13 AM

Ok, i've been meaning to do this for a while now.
 
Not sure why we dont already have a thread like this, probably no one has bothered. 
 
Quick disclaimer, PLEASE READ THIS FIRST
 
What i intend to do here is show and explain to be the best of my ability the different generation Holden Six cylinder heads.
 
This thread WILL NOT be a discussion on which one is best for this which one makes more power which one should i get ported bla bla bla, there is plenty of information on that already and any posts asking said stuff i will have removed. 
 
This is purely a discussion of stock heads and there physical differences to help you know what your looking at if your out in a paddock and spot one.
 
This will also NOT be a be all and end all guide, it may well be a living document with information added as time goes by. For instance im not certain on dates certain changes were made etc. 
 
Also keep in mind that these engines are old, have been through a lot of hands and have had a lot of changes made. Just because i say in this thread that a certain type of head should be on say a 186, does  not mean your 186 WILL have that type of head. It may have been changed at some stage so it comes back to you to decide what type it is by the physical differences. 
 
THere will also be no mention of combustion chamber volumes, i could CC 10 low comp heads and get 10 different figures due to rebuilds over the years. There is no way of telling what size chamber you have besides ccing it yourself. So please dont ask in this thread "what compression will i have if i put this head on this block" because there is ABSOLUTELY no way for anyone to know with any authority over a message forum. 
 
 
1ST REVISION
 
30/12/13
 
Moved some things around to make it more streamlined, i hope, added heaps more picks of items of interest, and a lot better description of the fundamental differences. 
 
 
With that out of the way, let the proceedings begin.
 
Firstly, a quick shot of part of my collection which i went through to find the different types
 
97FBFA27-F5B9-4FEC-975D-F674F3D554A4-208
 
Now, in my mind there are four generations of holden six head, Early Red, Late Red, Blue, then Black EFI.
 
These in my mind have significant enough changes to warrant a class of there own. 
 
Lets start With a basic rundown of the red 9 port.
 
All Reds are of a 9 port configuration. THey had a Siamesed inlet port with a large boss running down the center for the bolt, and individual exhaust ports. 3 inlet ports + 6 Exhaust ports = 9 POrts. 
 
THis is the inlet, including a pick of me fingering the port to show how the big wadd of shit in the middle is just the boss for the head bolt
 
DSCF0995_zpsfd913029.jpg
DSCF0999_zpsffd5dca2.jpg
DSCF0996_zpsf7034cd6.jpg
 
And the exhaust
DSCF0997_zps70e5781b.jpg
 
Here are picks of the two different chambers on the 9 port heads.
 
Low comp
DSCF1004_zps55bf65d1.jpg
 
High comp
DSCF1005_zpsec7dee4e.jpg
 
And both side by side
DSCF1007_zpsc4b2ac9c.jpg
 
 
And the location of the "L" or "H" to designate which shaped chambers it has, on 9 ports it is located on the manifold side of the head towards the rear, just between the last exhaust and last inlet port.
 
THese are low comps:
9FD0ED54-6085-4516-9824-13A3336E1AE6-208
DSCF1012_zpsc60b508f.jpg
 
And these are high comp
4522F885-17A6-4549-96E2-EB1B3C37DB23-208
DSCF1009_zps7e2c79a7.jpg
 
As i mentioned earlyer, i personally split them into two generations, each of which has two basic types, low and high comp. THere were a few minor running variations throught the cycles, but personally i dont think they really warrent mention, and i dont have enough data on them to comment with any authority anyway. 
 
 
 
EARLY RED.
 
THis is pretty well anything after the grey motor, and before the 202/173 came out, so circa 1971-72, if we could get a confirmation on this date that would be great.
 
The early ones are identifiable by there adjustable rockers on 3/8" pressed in studs, Square sided pushrod holes, a washer seal spark plug and five extra oil drain holes at the base of the rocker pedestals.  
 
These are the ONLY holden six cylinder head that you can fit stud mount roller rockers to and not have to use guide plates. All of the other heads you MUST use guide plates if going to stud mounted roller rockers, or use shaft mounted roller rockers. 
 
 
Early red head showing adjustable rocker gear:
AD0EE926-C6BB-414C-AE8A-39DCBADE42C2-208
47C7F85A-AB72-4E2C-B9E2-FD719E67763E-208
 
 
Square sided pushrod hole:
C4C49D28-E0EB-48DC-B79A-36B6672F92BD-208
 
 
Rocker gear dissassembled showing rocker, round pivot, and nut
804D4379-7276-4938-AA71-B9DDBA182873-208
 
Spark plugs, early washer type on right, later taper seal on left
E7A188E5-3EA8-4965-A8E6-2BD81F0FA0AD-208
 
 
Early washer seal plug hole
D302C3A8-515F-4910-87AA-E9B5A3F61711-208
 
 
One of the five extra oil drain holes, this is at the base of the rocker pedestal just inboard of the head bolt.
CDC8BB82-4D10-489B-8B3F-EDE7BD4D3C6A-208
 
 
LATE REDS.
 
These are basically the same appearance wise to early reds, bar a few small changes. 
 
They went to non adjustable bridge mounted rockers with 5/16" bolts, which to the best i can tell remained unchanged for the rest of the lifespan of Holdens greatest engine.
 
The pushrod hole became a 15/32" round hole, The extra oil drain holes at the base of the rocker pedestal were deleted, and they went to a taper seal spark plug. 
 
Somewhere along the range they recieved teardrop shaped divits in the top of the exhaust ports and appear to have boss's cast in, somewhat similar to the divots on the air injected 12 ports. This requires more investigation as i could only procastinate about there purpose at this point...
 
These changes remained for the following generations of Holden Six heads, bar where i note later in this speal. 
 
1F8449C8-32B9-42E6-886B-6994018305A7-208
 
Round pushrod holes, bolts instead of studs.
378B1600-5D8C-4F3D-844C-6FB721B1B09F-208
 
Bridge type rocker gear dissassembled. Note the square pivot of the bridge, which stops the rockers rotating sideways negating the need for square sided pushrod holes. This is why you MUST USE GUIDE PLATES if you go to stud mounted roller rockers on any of the later heads.
 
F83E5522-6881-46F5-A606-97FCBDC0E7F7-208
 
 
C19FAD39-EC27-4E6F-B42A-03F4499F3DE6-208
 
Closeup of the bridge assembly as fitted to a cylinder head. Note the two little arrows on the bridge, these face toward the valve upon assembly.
 
7A356A79-353C-4FF3-9F1E-7670357EB62F-208
 
 
Early and late side by side.
 
17C8A237-F11D-4BC2-8E31-79345A91A87F-208
 
 
Later model taper seal spark plug hole.
 
 
A68429EB-3454-45BE-8831-F93FD195365D-208


#2 _Bomber Watson_

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Posted 25 December 2013 - 10:38 AM

12 PORT HEADS
 
The 12 port heads brought about significant changes to the ports, this is covered at lengh elsewhere and as such will not be covered in any great detail here. 
 
A very basic rundown, the inlet ports were moved up, and made taller. There is now a full lengh divider giving each cylidner an individual inlet port as well as exhaust port. THe exhaust ports were made slightly narrower and slightly taller. 
 
The above description is significantly lacking, and does not go anywhere near explaining the lenghs Holden went to when designing the new head, but for a quick and nasty like this is I think its suitable for the time being.
 
They had hardened exhaust valve seats fitted to them, slightly longer valves with a higher installed height, subsequently longer valve springs that had dampners fitted. These are not interchangeable with earlyer model heads (early and late red)
 
The rocker gear remained the same as the late red.
 
The pushrod hole was enlarged slightly, to a bit over 1/2". I dont have a drill bit to measure it with accurately so 1/2" will do lol. They retained the taper seal spark plug from the late reds, they also got larger valves.
 
The "H" and "L" casting moved.
 
THe manifold mounting studs also moved.
 
And several water passage holes between the head and the block moved.
 
All 12 port heads had bosses in the casting just above the exhaust port for air injection nozzles. Some of these were drilled from factory, some were not. Information on precisely which ones were and were not is sketchy at this point so i will not provide more than a cursury glance at this.
 
I dont have any black efi heads laying around, sold the last one I had a while back, but there pretty hard to spot anyway and picks likely wont help much, so im leaving them out for now.
 
 
 
12 port port face
 
DSCF1039_zps1b55a8bc.jpg
 
Close up of the inlets
 
DSCF1037_zps799f36aa.jpg
 
And the exhaust
 
DSCF1038_zps64996025.jpg
 
 
"H" stamp, this is a high comp head. The stamp is located on the manifold side toward the front of the head, directly above #1 inlet port and just infront of the second head bolt from the front...... Followed by a pick of a 12 port high comp chamber
 
6A512837-918C-4E40-B2A5-73D3EC3BA4E8-208
 
5C47B7A8-BF86-4ECC-8F95-7A9551C8F626-208
 
04BF3B4B-025D-47C3-B753-8738825CBFC1-208
 
DSCF1027_zps3e161d5d.jpg
 
And "L" stamp, same spot. Hard to see, its much smaller than the reds. Followed by the chamber.
 
7EE10CA1-A781-4231-9F70-5B51E2E765CA-208
 
DSCF1026_zps78fd332a.jpg
 
12 port high and low chambers side by side.
 
DSCF1029_zps71f5bec1.jpg
 
12 port low chamber below red motor low chamber. 
 
DSCF1028_zps698928a5.jpg
 
And 12 port high comp chamber beside 9 port high comp chamber
 
DSCF1031_zps7d9fd19f.jpg
 
 
Note in the last picks the different water galleys in the heads. THe 12 port head has triange shaped holes just inboard of the head bolts on the spark plug side of the head, the 9 port does not, but does have two holes outboard of the head bolt hole.
 
Lets get right into that, by having a look at the obstacles that stand between swapping the two vastly different styles, 9 port to 12 port.
 
The first and foremost is a change in several of the water passages in the engines. I will attempt for now to show this with head gaskets. 
 
In this pick, Red is at the top, blue is at the bottom.
DSCF1019_zpscd913f70.jpg
 
It does not show up proeperly, but there are mismatched holes between 2 and 6.
 
Here we have the blue motor head gasket sitting attop of the red motor head gasket. 
 
The picture doesnt seem to show them up properly, but not the holes between 2-3 and 4-5.
 
DSCF1020_zps2ead36be.jpg
 
These dissimilarity's are all on the manifold side, and i will get back to them in a sec, but i noticed one on the pushrod side which i was not previously aware of whilst doing this comparo.
 
DSCF1022_zps4fde2b52.jpg
 
Thats between 5 and 6, and i'd never noticed it before.
 
Now moving back to the major alterations on the manifold side, some picks with the gaskets offset to give you a clearer view.
 
Red ontop of Blue.
 
DSCF1023_zpsa4d25688.jpg
 
Have a good look between 2-3 and 4-5. There are two ports in each point outwards from the head bolt in each section that do not correspond to the blue motor gsket. 
 
Now note the holes in the blue motor gasket, just inboard from the head bolt holes, between 1-2, 2-3, 3-4, and 4-5.
 
This is the difference.
 
A shot of the heads, blue motor has little triangle holes, red has two circular holes.
 
DSCF1032_zps74a15bf7.jpg 
 
Also note in the pick that the red head gasket ontop has little sealing swirls to seal up the holes in a 12 port head if you were to fit it to a red motor. 
 
This is a Proform gasket, same as Durapro. 
 
The ACL 12 port gasket i have has no such things, indicating to me again that ACL is over rated rubbish, but thats a different topic.
 
So basically if you wish to switch from one to the other, Hook into Ripco, Autobahs or Superjunk, or jump onto precision, have a good look at the gaskets they have on offer, and from there choose which side you wish to drill.
 
You can either drill your block out to suit your head and run a corresponding gasket, or drill the head out to suit the block and run a corresponding gasket. 
 
The best way to go will depend on gasket availabiliy.
 
If your somewhat excited, you can drill and tap the unused holes to fit grub screws, its probably reccommended but i dont think this is essential.
 
 
Next we move onto the manifod face, the various differences, why red inlet mani's wont fit blue etc, and why red extractors dont really fit blue.
 
12 port up the top, 9 port at the bottom.
 
DSCF1014_zps7cac3b9b.jpg
 
In that pick you can see the drastic difference in the height of the inlet ports as opposed to the exhaust ports. 
 
Also note the manifold studs, disregarding the two very end holes, 9 port goes "up down up down up down", whereas 12 port goes "up down down up down up"
 
THis is the first problem you will run into trying to swap between 9 and 12 port manifolds and extractors and the like.
 
9 port inlet manifolds are pretty well an entire no go, looking at that pick you should be able to see that the 12 port inlets are substantially taller than the 9 port. 
 
Also the exhaust ports of the 12 port are a bit narrower.
 
Now heres a few picks of the 9 port gasket layed ontop of the 12 port gasket. 
 
I tried to line it up as well as i could with the #3-4 inlet port in the side to side plane and with the height of the exhaust ports.
 
DSCF1016_zps9921d259.jpg
DSCF1017_zps9e3cec45.jpg
DSCF1018_zps3c9c7aa9.jpg
 
You can see somewhat clearly that nothing fits, and its a fair way off.
 
Your best way if you wish to graft some 9 port extractors to a 12 port is to buy or make a set of 12 port flanges, cut the 9 port flanges off, line everything up the best you can then weld the 12 port flanges on.
 
As far as inlet manifolds go, IMO dont even bother.
 
Right now im going to throw in a touch of oppinion, if your fitting a 12 port to something i see no real reason to mod the extracotrs, unless there already fitted and you have no other choice. The stock 12 port cast iron mani is a very nice looking unit, similar to the old Red X2 manifolds.
 
Same goes with the inlet, if you have a bit of ability i personally recon you can make the stock item work better than a $500 off the shelf item for most average applications, if swapping to a 12 port head.
 
By average applications i mean relatively stock 12 port, baby cam up to 230 @.050", the like.
 
Ok, that little transgrssion into my oppinion as opposed to what i realize as fact is out of the way, lets continue on with a few more known and provable points.  
 
 
 
 
Now thats pretty well it, i think i've covered basically everything i wanted to cover, the major differences and how to identify them quickly and easilly. While were going though i'll put in a real quick word on how to spot a Yella Terra head, as this gets asked a bit.
 
They all have a stamping on the back of the head in the flat section, as below
3E2295AB-5DE8-4A41-91E9-7A2946114D73-208
87E264F8-FAA3-4CFB-A084-91581A1C335E-208
 
And the ports should look something like this, TMK this is a stage 3.
 
2D893D64-E30D-4CFD-9C4E-52AD16E6844D-208
 
As i said i just thought i would chuck that in incase anyone was wondering.
 
Hope this helps someone.
 
Cheers. 


#3 N/A-PWR

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Posted 25 December 2013 - 10:51 AM

So thank's to you DJ,

I have an Early Red ( slots ) and had adjustable 3/8 studs put in:-

 

Attached File  IMG_4426.JPG   40.97K   20 downloads

 

also this is a Stage 5 Port:-

 

Attached File  IMG_4427.JPG   32.83K   26 downloads



#4 _oldjohnno_

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Posted 25 December 2013 - 02:03 PM

Great stuff Bomber, there's a need for this sort of info.



#5 _Lazarus_

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Posted 25 December 2013 - 03:07 PM

When you say the 12 port heads had hardened seats 'fitted to them' were they inserts or just flame hardened ?

 

 

I have one I bought with inserts but I was under the impression these were fitted as part of a gas conversion.



#6 _Bomber Watson_

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Posted 25 December 2013 - 04:01 PM

Every one i have looked at has inserts on the exhaust valve, i assume they were all like that.

 

As i said, this isnt a bee all and end all, just differences i have noticed looking at my personal stash, there wernt any books or googles consulted in the making of this little guide lol.

 

Cheers. 


Edited by Bomber Watson, 25 December 2013 - 04:10 PM.


#7 _Muzzy_

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Posted 25 December 2013 - 04:27 PM

Just to throw in I cc a blue closed chamber head and a red one today, they are the same at 46cc

#8 _Bomber Watson_

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Posted 25 December 2013 - 04:29 PM

Yep that seems pretty normal for high comp heads that have been reasonably untouched. 

 

Cheers. 



#9 _Muzzy_

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Posted 25 December 2013 - 04:30 PM

Thanks good learning for a newbie like me
BTW
I CC ed my blue and red head today both came in at 46 CC

Edited by Muzzy, 25 December 2013 - 04:32 PM.


#10 _Bomber Watson_

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Posted 25 December 2013 - 04:42 PM

THe more i look at this the more im not overly happy with it, i admit i fairly rushed it, had a bit of time to kill this morning between walking the dog and heading off to do the whole be nice to the family thing, and i cranked the above out in about 2 1/2 hours including taking the picks which sounds like plenty of time but it was pretty rushed. 

 

I'll have a bit of a play around in wordpad and get a mod to edit it when im more content, in the meantime, anyone have any ideas on how to improve?

 

I think we need more and better pictures showing the difference between 9 and 12 port heads, after all this is intended as a brain soak for someone who has never seen a holden six before and i pretty well glanced over one of the major factors, anything else?

 

Cheers. 



#11 _Muzzy_

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Posted 25 December 2013 - 05:53 PM

You could add the size of the valves as this is handy when building an engine

#12 _Bomber Watson_

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Posted 25 December 2013 - 05:56 PM

Hmmm i considered stock to be pretty irrelevant, but i will do.

 

Cheers. 



#13 _Muzzy_

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Posted 25 December 2013 - 06:11 PM

The idea behind that is to inform people if the valves fitted are std or oversize
Another brain wave

Measure the head thickness from face to a. Head bolt machine face
The reason for this, one could work out if the head has been decked

I'm happy to provide any info you want on the red 173 head, as I know it is std, we knew the owner and have know the car for 30 years and it's a 1 owner vehicle

#14 _Bomber Watson_

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Posted 25 December 2013 - 06:14 PM

Yeah righto i'll see if i have enough untouched stock ones to do a comparison. Know i have one there atleast, just gotta remember which one it is....



#15 _Gunmetal LH_

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Posted 25 December 2013 - 06:32 PM

Cheers Bomber.

 

Was wondering are the valves sizes the same all the way through?



#16 _Bomber Watson_

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Posted 25 December 2013 - 06:36 PM

Na blue/black are bigger.



#17 _Gunmetal LH_

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Posted 25 December 2013 - 06:40 PM

Scroll,

Scroll,

Scroll,

Scroll,

Scroll,

Scroll,

 

Coolies.  How much bigger?



#18 _Bomber Watson_

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Posted 25 December 2013 - 06:50 PM

About 6 periwinkles on the inlet and 4 dooglebugs on the exhaust bigger. 



#19 _Gunmetal LH_

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Posted 25 December 2013 - 06:59 PM

:lol:



#20 _Bomber Watson_

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Posted 25 December 2013 - 07:02 PM

Translation is i cant be #@$^%& measuring them atm....



#21 _oldjohnno_

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Posted 25 December 2013 - 07:59 PM

THe more i look at this the more im not overly happy with it, i admit i fairly rushed it, had a bit of time to kill this morning between walking the dog and heading off to do the whole be nice to the family thing, and i cranked the above out in about 2 1/2 hours including taking the picks which sounds like plenty of time but it was pretty rushed. 

 

I'll have a bit of a play around in wordpad and get a mod to edit it when im more content, in the meantime, anyone have any ideas on how to improve?

 

I think we need more and better pictures showing the difference between 9 and 12 port heads, after all this is intended as a brain soak for someone who has never seen a holden six before and i pretty well glanced over one of the major factors, anything else?

 

Cheers. 

 

I wouldn't be too concerned, I think it's better to get it out there and then polish it up over time. In my experience if you wait til it's perfect before you post it'll never happen.

 

One of the things that comes up here all the time is the differences in the coolant holes, especially when fitting a blue head to a red block or vice versa. Another regular question is extractor interchangeability.



#22 _Bomber Watson_

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Posted 25 December 2013 - 08:06 PM

frOck i didnt even think about the coolant holes. Good call.

 

And the difference in manifold stud positions.

 

Good calls.

 

Cheers. 



#23 Stinga

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Posted 25 December 2013 - 08:58 PM

Good write up bomber, perhaps someone has some pics to add of the efi head which you didnt have? and maybe have it pinned in the engine section, then in time as stuff is added, have the suggestions removed so the thread isnt cluttered, and send stinga a life supply of your home brew as he is a poor dad now.

 

cheers



#24 _Bomber Watson_

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Posted 25 December 2013 - 09:07 PM

Lol.

 

Got beer sorted, im set up real good more or less....

 

Looking at making a still now.....Dont tell anyone.

 

Cheers. 



#25 _hutch_

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Posted 26 December 2013 - 09:17 AM

if you where to build a still bomber the product produced would be only used in the interests of science in any case.....right ????/




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