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Model specific boards => Golf mk2 => Topic started by: roberto on 24 August 2014, 17:54
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hey folks. bit of an odd one this but here goes. does anyone know if it would be ok to mix single and double valve springs in the same cylinder head? my plan was to fit agg exhaust valves/guides and springs in my pb head but leave inlets standard.
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Why? Firstly the pb head has two springs which is supposedly more than enough for every application other than ridiculous high lift and snappy cams. What are the the aug valve sizes, lengths, diameter (shank and head), and collet groove count. It just seems silly. There are already off the shelf 35mm cutback exhaust valves for a pb head. Rec will do you a set for £90 delivered for all 4 and the springs are plenty good enough. I can dig out the valve number for them if you want.
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well the thing is. I already have the complete agg valve assemblies and my head needs new guides so with the pb and agg guides costing the same I thought why not put the more streamlined valves(agg) in during the rebuild. valve head is same diameter but with 7mm stems and a less restrictive profile between stem and head. the springs/collets and top caps are not interchangeable so the single agg springs would have to be used. just not sure if it would bother the engine in any way having doubles on inlet and singles on exhaust valves. 90 quid for the 35mm valves then you need the seats to match and the head machined to accept it all. cant justify the cost really.
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If it's just because you own the other parts already you might as well. It's just going to be virtually unnoticeable in the flow characteristics of a completely standard head.
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I will be doing some light port work/3 angle seats/decent skim and mild cam. so every little helps :cool:. aiming for 130ish bhp.
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The outside diameter of the two types of valve guide is the same, is it?
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No pb valves are 8mm but if you are doing new valve guides it might work. A valve cutback would be beneficial.
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Outside dia of guides. :wink:
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No pb valves are 8mm but if you are doing new valve guides it might work. A valve cutback would be beneficial.
yeah im planning on getting the valve back cut just in from the seat.
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The outside diameter of the two types of valve guide is the same, is it?
yeah the guide o/d is the same on both.
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soooo any of you fellas have an answer to my original question? :huh:
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Surely if the valve length is the same and there are matching springs and collet washer it shouldnt matter really. I would put on the pb dual springs and collet washer if the collets are the same groove style for the different valves. I still don't see where the gains are to be had. Guide work wasn't cheap when I had it done. £5 a valve guide plus £5 for them to be honed plus vat. That's £50 to fit valves with a slightly thinner shaft.
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but the thing is that the double springs wont work with the agg exhaust valves. the collets/caps and springs are all different. the agg inlets are longer than the pb ones so not sure I want to risk fitting them as they might bottom out the tappets after the seats in the head have been re-cut. which is why I want to retain the original inlet valves. £5 for each guide :shocked:. I have ordered a set of febi guides from gsf for £3.20 each.
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I forgot the cost of the guides themselves. Where are you getting the guides fitted and honed at?
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fitting the guides myself. not sure where im getting the clearances done yet.