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"Tight valves"

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Old 12-15-2015, 10:04 PM
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"Tight valves"

Let's make clear about "tight" valves.
When the clearance between valve and screw at the end of rocker arm is too small, the valve opening phase will be wider than intended (so the valve will open earlier and close later).
If both valves "too tight" the time of valve overlap will increase.
As a result the idle and low end torque will be poor, however it will be surge of power close to the redline, like on the racing engine (many of them have large valve overlap to promote better flow in and out of cylinder at high rpms without using large valves) Using cone shaped megaphone exhaust (as seen on older modded Bugs) will increase performance even more

The frequent need for valve adjustment IMHO is caused by using cheapo oil like Chalet or Valucraft that wears rollers in the rocker arms.
 
  #2  
Old 12-16-2015, 08:27 AM
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Originally Posted by doctor J View Post
The frequent need for valve adjustment IMHO is caused by using cheapo oil like Chalet or Valucraft that wears rollers in the rocker arms.
You should not make a generalization like that....

Any motor oil that meets the recommended API spec, and that is replaced at the intervals Honda recommends, should do fine. That is what Honda says (or has to say).


We use only name brand Group III synthetics in our Fit, and the clearances change more than in our CR-V (which uses the K24 engine).


 
  #3  
Old 12-16-2015, 09:58 AM
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It may be subjective but, my relative with 2008 Fit Sport (90k miles, original coils and plugs, Valvoline oil since day 1 changed every 6000 mi), was "sold" the valve clearance inspection and the valves were in specks. The car has no driveability issues (it was used in NJ for 6 years now is back to CA).
On my car I use Autozone oil 2 times and the engine was somewhat noisier 3k after oil change compared to the Quaker state oil I used on other times.
 
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Old 12-17-2015, 03:04 AM
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At this point with so many people having issues with the L15a engine valve clearance I believe it to be a harmonic issue. Every 40k miles I check the valve clearance and my intake almost consistently loosens up .02 and the exhaust tightens .03.

This is coming from an engine that has used royal purple 5w20 with a zddp additive since day one. I'm now at 192k miles.

This past oil change I finally switched things up to rotella t6 5w40 to see if this will make any difference.
 
  #5  
Old 12-17-2015, 10:41 AM
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Every car is different but I remember my co-worker's 95 Mitsu Mirage with "tight" exhaust valves; it failed smog as gross polluter for 1000 PPM of HC at idle and the engine was dying in drive after cold start unless it warmed up for 3 to 5 minutes
 
  #6  
Old 12-18-2015, 12:18 AM
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LOL it just wasn't that long ago that pretty much all imported cars needed valve lash adjustments or at least checked about every 12K miles.

Heck a 72 bug needed the valves checked ever 3500 miles (At every oil change...)
Took me 10 minutes on average, but you could remove the valve covers with you hands...

 
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Old 12-18-2015, 11:20 AM
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On my 79 Supra the valves had to be checked (and adjusted) with engine HOT
 
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Old 12-19-2015, 12:02 PM
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Originally Posted by kylerwho View Post
..with so many people having issues with the L15a engine valve clearance ...

I'd like to hear others comment on this. Is this a known issue or a forum-based anecdotal perception? Is there a dedicated thread? If not, could we start one?

Because problems are disproportionately discussed on internet forums, an issue that affects, say, 3% of cars in the real world may become an issue that is discussed online 30% of the time. I'm not saying the valve issue does not exist. I'm just asking for more feedback.

Thanks.
 
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Old 12-19-2015, 10:27 PM
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IMO more people are having problems with water leak to the spare tire well.
 
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Old 12-20-2015, 12:55 AM
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We could start a thread with a poll, I guess.
 
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