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Floating Valves

Discussion in 'Engine Building' started by jpoenitsch, Apr 18, 2005.

  1. jpoenitsch

    jpoenitsch Member

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    HISTORY: Have a 89 CRX enduro car, recently put the 8 valve head on the 16 valve block. I used my 16 valve intake and injectors.

    PROBLEM, if you read 8 valve on 16 valve engine thread you know the whole story.
    Rev's to about 4900 rpms and then the engine bogs down, like it is under a load, not like its on red line.
    I have swapped just about everything (ecu, fuel pump/filter, dizzy, tps, injector resistor, all wiring) with no luck.

    I have never heard the 8 valve run so I have no idea how it ran before. Anyways the springs seem to be pretty sloppy, like I can compress them with a plyers and pull the keepers out easily with out the use of a spring compressor. Somebody said valve float but I have no idea what the symptoms are.

    Any info on this or experience? advice? :unsure:
     
  2. erikespo

    erikespo Senior Member

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    I have no answer, but i have a question for you? Why are you using such a crappy head?
     
  3. drpenguin

    drpenguin Senior Member

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    I have a crx HF getting the b16 swap right now. I can tell you this. That 8 valve head that was on my HF red lined at 5G. I dont know what head you have so this may be of no use. just get a DOHC






    P.s. If you got a HF head were you atleast lubed up when you got it? :blink:
     
  4. jpoenitsch

    jpoenitsch Member

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    This is an enduro (race car) for circle track. I am putting the 8 valve head on because this year they changed the rules and don't allow 16 valve engines, because we were to dominant last year.

    The head I have is off of an HF.

    The HF does red line at 5000 rpms, however on a HF car I drove it max-ed out at 5900 rpms.

    I put my 16 valve head back on to make sure this was a head issue and I confirmed my belief, the 16 valve ran fine and went all the way up to 7000 rpms.

    So, why doesn't the 8 valve head work?
    Floating valves. I have no idea how many miles are on this engine, but the "free spring legnth" is very close to service minimizations. (meaning they are worn)

    Next? Trying a different 8 valve head off of a car that I have driven. Last night I was able to take that car to 6000 rpms before the rev limiter kicked in. Going to swap it out this morning, should have an answer by lunch.

    If any one knows about this issue let me know. I am looking into putiing my 16v cam on the 8v head in the future...., ITS looks possible believe it or not. :)
     
  5. drpenguin

    drpenguin Senior Member

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    Okay well thats is your problem the HF head. Get a DX head and it should be better. DX heads are 8 right? I dont know much about heads but from what i have heard the DX head will rev alot higher then the HF. Everything on the HF is for fuel economy or how ever you spell it! You wont be able to get that HF head above 6g with out some work that honestly isnt worth the metal the head is made out of. as for the rev limiter My hf didnt have one. I reved it to 7g and killed it. God that was sweet!
     
  6. jpoenitsch

    jpoenitsch Member

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    Yea, the DX head is also 16 valve. I disected both the 16 valve and 8 valve heads and learned alot. :)

    In both heads the valves are exactly the same (height/ width, etc.)

    The valves also open the exact same distance on both heads.

    The 8 valve cam just seems to have a longer duration keeping the valves open longer than the 16 valve.

    THE PROBLEM IS FLOATING VALVES.

    SO what I did was I put my (16 Valve) springs into my 8 valve head, since there was a big difference in tension. Well it worked. :D Now I can take it to almost 6000 rpms before it rev's out, meaning thats all the cam has got (duration). A big difference from before!

    Anyone know any good places to look for cams???


    Thanks for the reply though!
     
  7. racintweek

    racintweek Senior Member

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    webcams. they make cams for all kinds of engines
    and they arent too much $$$$$$$$$
     
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