from memory holden 6 cyl yt heads mainly where classed stage 3, for the 186/202.
these took any s/h 186/202head, cnc computer then ported the intake exhaust, combustion chamber, fitted the intake tube, bigger valves etc. good bang for your buck, oh, and some yellow paint.
so regardless of the casting origin, it was the same finished product.
the cnc heads were noticably done by cnc, lots tool marks.
then there was the stage 4,5 and 6. six was called 6000, think the 12000 was the 12 port.
these were painted red, not gm red/orange.
these heads were the early head castings to raise compression (when there was lead in the fuel), like the 149 shape,
think they used 161 as well, depending on the level of performance.
lots people made copies, even using yt valves and yellow paint.
they recon that removing the post on the intake altogether caused flow problems, best was to glue in a seperator once head was installed, so it goes?
sure someone will know exact history.
Identifying a true yella terra head?
Started by
rodomo
, Mar 15 2009 12:58 PM
38 replies to this topic
#26
bryanw
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Posted 04 April 2009 - 11:07 PM
#27
_1QUICK LJ_
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Posted 13 April 2009 - 11:22 PM
think they may just be recon codes
Edited by 1QUICK LJ, 13 April 2009 - 11:22 PM.
#28
_Allports_
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Posted 13 April 2009 - 11:31 PM
Removing the post completely is not an issue if you have a decent bottom end. I ran one like that for years in a front engine rail and incidently when I tried all sorts of seperator plates to make it a "12" port so to speak it didnt do anything except a slight drop off in MPH. Although ET remained much the same.
#29
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Posted 03 November 2010 - 11:07 PM
Jono.
I have a 9937263 head listed has a 173/2850 ADR27A head
4J9 means it was cast on the 4th of September 1979 so off a VB commodore I would think ( HR's and HQ are more my thing ).
If you can all bare with me on this I have been trying to sort a head ID guide out for red heads and we appreciate any comments and corrections
on what I have so far.
On the stage 1, 2 and 3 thing.
There is always a lot of different views to that one but if you have a look at this picture
http://gallery.oldho...ageViewsIndex=1
and this one
http://gallery.oldho...ageViewsIndex=1
That is what perfectune (Y/T) called a stage three back then.
Interesting to note in this advert stage 1, 2 and 3 heads which are listed as hand finished items and Yella Terra as a separate item and is listed as machine modified.
Rodomo I was also told that the early Y/T heads did not have Y/T on the valves and looking at that picture those valves do not have the Y/T on them.
I was told years ago a stage one had slighty over size valves and it had been throated to suit those valves. With basically minor port work done.
stage two was std inlet post removed and a insert post fitted with both inlet and exhaust ports were ported and match ported to the inlet gasket with slight larger than stage 1 valves fitted.
Stage 3 I always thought looked like this.
Where the inlet posts had been removed totally and a Hex head bolt was used instead of a std head bolt.
they also had duel springs, larger that stage 2 valves and had been decked.
But after looking back through my old magazines and finding the adverts in the links above I know that is not right.
But to add to that I have now been told that they tried the removal of the post altogether as in the picture and they had problems with the heads cracking so then they went to the insert post design instead.
Like in Jono's no 3 picture.
If you have a look here
http://gallery.oldho...ines/red+heads/
I have a selection of pictures which now have to be renamed showing a std head, a slightly modified head (stage 1)and a more modified head (Stage 2 which is actually possibly really a stage 3 head)
Since doing these pictures I have been doing a pictorial record of casting numbers verse chamber designs which is here.
http://gallery.oldho...yl+Casting+ids/
The only problem is that I have came across one casting number with two designs.
Both of these heads are modified with larger valves and the second picture is a possible Y/T head where as I am not so sure if the first one is a Y/T or not.
Both are 7429477 casting number heads one with a B97 9 2 67 date code and the other with a B237 23 2 67 date code but as you can see totally different chamber designs.
Any ideas on this anyone
So from this I am interested in any pictures I can come across of any other chamber/casting pictures that I do not have.
Cheers Paul.
I know this is a old thread, I came across it doing a search.
The large combustiom camber is I beleive a yella terra preped turbo head, A mate had one pretty much the same on his turbo 202 that was built way back when.
#30
evl666
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Posted 11 May 2014 - 10:47 PM
Are these 'reco markings' on the front or back side of the heads?
#31
rodomo
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Posted 11 May 2014 - 10:58 PM
Back
#32
_BW Yella Terra_
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Posted 23 May 2014 - 05:04 PM
Hi Everybody!
I work for Yella Terra, My name is Brenten.
I had a call from someone this afternoon asking if YT cast our own steel heads back in the day. The answer is yes we did.
The person who called was given bad info, apologies.
There are a ton of crossovers though, with many factory heads that were re done by YT are almost identical.
Hope that clears it up for some of you.
#33
_Frankenstein UC_
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Posted 06 November 2015 - 07:37 AM
This is what a true y/t job looks like.
Edited by Frankenstein UC, 06 November 2015 - 07:48 AM.
#34
_Bomber Watson_
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Posted 06 November 2015 - 06:39 PM
Aaahhh yes one of those.
#35
_Frankenstein UC_
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Posted 12 December 2015 - 07:36 AM
I've just aquired a nice yt head. It has been rebuilt by MIA DYNO SERVICES, in Cromer, Sydney. It has 2008 stamped on it. No yt on the new valves but they are thick mothers! Crane double springs etc. Brett builds a lot of red motors for the HQ racers and there's not much he doesn't know about all things red six. He's a good go to man when you need info. He can ream out a stocker and make it to any spec. Sorry I can't seem to post pics of the port, chambers and post work on my new head. I finished tieing it down yesterday. The compression went upto over 10 to 1 and the torque increase is very pleasing. This is basically a stg 3 job onto a standard 202 with extractors and rebuilt strommie. The good manifold and 380 2 barrel ought to bring it upto about 145 hp. Not bad for stock and a total cost to me of $1190.
#36
N/A-PWR
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Posted 12 December 2015 - 12:48 PM
Thank's for reviving Rob's thread,
I know mine isn't a YT head, but actually a HQ 186 one, as we found out,
but after reading here about the stamp marks on the back, this head reads,
AC 15 491 Ɔ (this 'Ɔ' is the same stamp as the first 'C'),
does anyone know what this stamp arrangement means?
most appreciated, and a couple of pictures here:-
Wilkie Stage5.jpg 60.09K
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Wilkie Stage 5.jpg 73.83K
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#37
N/A-PWR
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Posted 12 December 2015 - 02:16 PM
After doing a bit more research,
could the 'AC' mean, ACDELCO.
also this head is 'HR' and not 'HQ' as first thought:-
6cyl 186 12-9-67
7429461 F1 7 3 L
AC 15 491 C
AC 15 491 Ɔ (this 'Ɔ' is the same stamp as the first 'C'),
does anyone know what this stamp arrangement means?
#38
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Posted 13 December 2015 - 09:26 AM
Dave, at first I thought 15 491 is a job number but perhaps it is 15 4 91 (15th April 1991?). AC may be the initials of the workshop or bloke that rebuilt the head?
#39
N/A-PWR
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Posted 13 December 2015 - 11:44 AM
Hello Dave and thank-you,
Great idea there, only,
the only time someone swapped the valves around in the head, probably about 1986/7,
other then that, was when 'Wilkie' converted it to what it is now, pre-1980, hmm.
In any case, I am going to contact them and ask if they have any records of the number.
Dave, at first I thought 15 491 is a job number but perhaps it is 15 4 91 (15th April 1991?). AC may be the initials of the workshop or bloke that rebuilt the head?
Sorry for the thread steal.
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