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Thread: Valve shims causing low compression?

  1. #21
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    That could possibly be something to do with the map on Vems, although we looked at the start up section and it seemed ok. I will get them to have a look and see if that is wired in. The engine does just sound lazy when turning over also though.

  2. #22
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    Looking at the section in vems won't tell you if the wire isn't connected, just shows you enrichment figures vs temp.

  3. #23
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    Also if it had low compression it would sound the opposite of lazy. Maybe when you were doing the compression test there wasn't enough juice in the battery and turning it to slow to get a good figure.

    I usually pull all the plugs out when doing a compression test so the engine can turn quicker and the battery doesn't have to try so hard.

  4. #24
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    From memory I'm sure it had injector pulse rates etc in it also and when the injectors had to put fuel in after the initial cranking. I will mention it to them about the crank wire though.

  5. #25
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    Negative it puts extra fuel in while cranking to start the car.

  6. #26
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    After that it's cold start fueling

  7. #27
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    Will mention this to them. Main issue will be sorting the missfiring issue. When I've had this problem in the past changing the sparkplugs over and the car started again ok & would drive ok.

  8. #28
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    Injectors being modified scares me, buy new genuine nismo 740's to rule out mis matched injector flows


    JC SX

  9. #29
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    Jc this engine setup was running spot on before Scottish sr bought the package.

  10. #30
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    Doc got the injectors from Polo who had them running at 500bhp.

  11. #31
    Guest JC SX's Avatar
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    Valve shims causing low compression?

    Just from personal experience, injectors are such a key item, to run modified and untested items even from a known source is risky, me personally I'd never take a second hand injector set as well I'd rather shell out for new from a genuine supplier.
    Fake nismos, lean cylinders and blown engines all taught me this the hard way. ££££
    Agree with the consensus on the diagnosis, I had valve float and valve bounce on my Sr running 3a power and 1a before I upgraded the head to Tomei Titanium valve springs and retainers and uprated cams


    JC SX

  12. #32
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    Understand what you are saying RE injectors. Unfortunately I spent all my ££ on the engine and now looks like the head needs upgraded.

    I would have thought that it would not have even boosted well if valve bounce/float was happening?
    Although that's what it sounds like when it's missing.

    I see H-Dev sell uprated cosworth springs, may purchase them then. Don't really want uprated cams as it will be running enough power.
    Last edited by scottish-sr; 04-07-2014 at 09:04.

  13. #33
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    Spoke to the garage there. Looks like valves on all cylinders are burnt, worst being cylinder 4, they suspect these are being held open once the engine is warm due to clearances not being set right so the valve is not closing fully.

    Has anyone ever ordered from FRSPORT? How long does it take for stuff to be sent over. Thinking of the BC Valve springs and retainers and possibly valves.

  14. #34
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    You can get bc valve springs from h-dev. No need to upgrade the retainers as they are single spring.

  15. #35
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    Shall speak to H-Dev. The only ones I seen on their site were Cosworth ones.
    Just waiting on a quote for the work, it's getting e-mailed, probably be ££

  16. #36
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    I bought bc springs from them last year for £130

  17. #37
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    I would recommend upgrading the retainer too. BC titanium retainers A LOT lighter that the stock ones. And the set with the retainers and springs is not that expensive from FRSport...

  18. #38
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    Sure it worked out around £170 shipped from FR for springs & retainers

  19. #39
    Banned sideways14a's Avatar
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    Yeah definitely get the retainers, once you do that and stuff on a ras kit the top end of the SR is "relatively" safe for revs.

  20. #40
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    frsport are good, have ordered a few things from there over the years.
    2004 - on : 1999 S14a 398bhp 378lb/ft
    2010 - on : 2007 RX8 PZ
    1998 - 2004 : 1991 S13

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