Bigger valves EG engine

Discussion in '8-valve' started by Djoene, Jan 22, 2020.

  1. Djoene New Member

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    Hi all,


    I am rebuilding a Golf 1 gti 1.6 engine (so the EG). And I was thinking about replacing the valves, and maybe get some bigger. And getting a Schrick camshaft + stiffer springs.

    But I don't know how big I can go for that. Did somebody do this already ? And to what size did you go then ?


    Thanks !!
     
  2. Jon Olds Forum Junkie

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    I have a race EG with 40:35 valves. Doubt you will get much bigger in. Schrick springs. Fancy top caps.
    Not a cheap build.
    The issue with EG's is getting the compression up, and allowing for pockets in pistons for cams with big overlaps (lift at TDC)
    Jon
     
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  3. mr hillclimber Club GTI Supporter and Sponsor

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    I'm with Jon. If your still on the STD bore size you won't usefully squeeze an inlet valve bigger than 40.5mm down the bore. The last time I checked there were 40mm inlets available. I'd not go bigger on the exhaust valve size unless it's a competition engine. In fact, I've seen decent gains from porting on the STD valve sizes on these heads with only basic development...more than enough for fast road type use.

    As for a cam, I'd stick to 268 duration and 0.425 peak lift as that will work with the relatively low std C.R and the STD valve springs, and should have enough clearance @ TDC and not upset the STD kjet injection for road use.
     
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  4. Jon Olds Forum Junkie

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    These are a nice engine, overlooked by everybody now. Make sure you use super quality oil if you are chasing high revs. They are a heavy piston
    and give the big end bearings a hard time at dizzy rpm.
    Got a couple of spare used cams, (GS2 and a schrick) but not everybody likes re using cams. Must be a mech type, not hydraulic. Will need reshimming
    Jon
     
    erreesse likes this.
  5. mr hillclimber Club GTI Supporter and Sponsor

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    I think parts availability is part of the reason for that Jon...good blocks are very hard to get now.

    I fancy doing a longer rod version with a shorter/lighter custom piston and some proper squish.
     

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