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Pierce 7 Port Head - Valve Suggestion


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#1 Java_Green

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Posted 22 January 2022 - 01:19 PM

I am about to build a fuel injected (plenum chamber with single throttle body) supercharged big bore engine with a Pierce casted 7 port head. The head is a bare head and my aim is to build a street car not a screamer. Any advice considering choice of valves and in particular valve sizes? 



#2 IronmanG

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Posted 22 January 2022 - 03:55 PM

Following with interest. What supercharger?

#3 sonikk4

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Posted 22 January 2022 - 07:43 PM

Following with interest. What supercharger?

 

Graham, what size valves are in your head??



#4 IronmanG

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Posted 22 January 2022 - 07:49 PM

35.7 and 31 as per SC.
What I took from the head they supplied was, and depending upon the cam used, a set of OAP conical springs are better than double springs.
As for valve make again ask Oz what he would recommend

Edited by IronmanG, 22 January 2022 - 08:20 PM.


#5 sonikk4

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Posted 22 January 2022 - 08:36 PM

35.7 and 31 as per SC.
What I took from the head they supplied was, and depending upon the cam used, a set of OAP conical springs are better than double springs.
As for valve make again ask Oz what he would recommend

 

Defo agree with this, Oz has also fitted a set of his conical valve springs instead of the SC supplied items that came with my SC Billet Aluminium cylinder head. The supplied springs are too strong and potentially cause issues with the seats.



#6 IronmanG

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Posted 22 January 2022 - 08:43 PM

Also Alex at car kitchen is just working on a supercharger setup for the 7 port.

#7 Turbo Phil

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Posted 23 January 2022 - 12:34 PM

The Pierce castings used to come with 33/29mm valves. Is there enough material in the inserts to cut for much larger valves?

Phil.

#8 PoolGuy

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Posted 23 January 2022 - 12:43 PM

Java, did you buy the bare head directly from Pierce?



#9 Java_Green

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Posted 23 January 2022 - 01:10 PM

Originally I am fairly sure that the head comes from Webcon.

From what I remember, the valve guides are further apart and it looks like there is room for larger ones (I have read that there is people who have put in larger valves). I do have a set of 36.6/29.0 (new) and a set of 35.7/31.0 (used) on the shelf. Flow wise I want to use valves mating the ports.

An additional question, when is it fine to reuse valves? There are marks and shiny areas on the stems, but nothing that I can feel with my nails.

Standard rocker ratio (roller tip) of 1:1.3 and Kent Cams 276.


Edited by Java_Green, 23 January 2022 - 08:54 PM.


#10 Turbo Phil

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Posted 23 January 2022 - 03:38 PM

You need to measure the valve stems with a micrometer, anything more than 0.0005” wear and they can be considered scrap.

Phil.

#11 Java_Green

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Posted 24 January 2022 - 08:12 AM

Phil,

 

You are expert in "the flow field". What is your recommendation considering choice of valve sizes with described set up?






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