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308 Heads


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#1 _Barman_

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Posted 18 June 2006 - 07:28 PM

When i bought engine the guy said "yeah mate there yella terra heads"
I didnt believe him but it was cheap, so now that ive got it stripped these heads have monster valves and double springs (compared to my spare 308 heads)
So is there any way to know if they are or not ? (do they stamp them anywhere)
thanks Baz

#2 _[BOTTLEDUP]_

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Posted 19 June 2006 - 09:23 PM

In a word NO.

Tho Yella Terra heads run Yella Terra valves, if they were purchased complete. They'll have YT stamped in the valve face.

#3 Struggler

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Posted 19 June 2006 - 09:35 PM

Check the exhaust port at the extractor face, YT's are machined on the roof of the port (to make it taller). Also the chambers are machined around the intake and exhaust valves, but this is easy to replicate.

#4 _Yella SLuR_

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Posted 20 June 2006 - 03:35 PM

Make this 1,001 times:-

God, feel like I've posted this 1,000 times now. Think it must be on the old site. This is all from a 308 perspective by the way, not sure about variants on the six heads.

Early Y/T heads have no identification at all on them, were painted Holden Rocket Red, Holden still cast into them, no Y/T on the valve faces. I don't believe they came in Yellow till the 80's, except for the adverts. The only way to identify the early ones are much larger valves, nearly double standard, modified combustion chamber to take the bigger valves (valves about 50% bigger than the L34 valves even), and the valves have the black tuft-riding on them. The inlets have minimal machining, but you'll find that there is no sharp casting edge in the inlets/outlets.

A set of early 308 Yella Terra's with hardened exhaust valve seats.

Posted Image

Later Y/T heads actually had the valves with Y/T cast into the face.



#5 Struggler

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Posted 20 June 2006 - 09:21 PM

The only way to identify the early ones are much larger valves, nearly double standard, modified combustion chamber to take the bigger valves (valves about 50% bigger than the L34 valves even),


I beg to differ....... Yella Terra have never fitted a bigger than 1.94/1.50 or L34 size valve combo to a cast iron 308 head, the valve spacing wont allow it. When they made their own alloy heads they fitted 2.02 intakes but had to spread the spacing to do it.

#6 _Yella SLuR_

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Posted 20 June 2006 - 10:29 PM

Just roughly speaking Struggler for a visual ID on em. I must say I've never measured em, just a visual thing. I've got some standard heads, one L34 head, and then these suckers. Can measure the first two, but these ones are a bit hard to measure now, but you can see they are just about touching in the middle (can't be any bigger), and have the modified chamber when compared to the standard or L34 head.

I thought these valves where huge, then the dude that did the heads showed me some GT351 heads......make these heads look tiny in every respect.

Edited by Yella SLuR, 20 June 2006 - 10:31 PM.


#7 _Barman_

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Posted 21 June 2006 - 08:00 PM

thanks guy ,,,Its as clear as mud now
Ive got yt heads thanks Baz




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