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Valve clearance adjustment I'm actually happy with.

Engine/Gearbox questions and discussion
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Scott560
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Valve clearance adjustment I'm actually happy with.

Post by Scott560 » Sun Sep 16, 2018 6:23 pm

I've never been happy with the valve adjustment process in the manual. Did it on my old h22a5 and a b16a2 and whilst not terrible, wasn't happy with the outcome.

After painting my rocker cover last month before the thruxton track day, I did the adjustment with an assistant. Using the special screwdriver socket tool and some feeler guages, we thought we'd done a good job.

Started up the next day and it was way worse than before , and worse than others I'd done. My reconning was the manuals term 'light drag' was nonsense.
Manual clearly shows the guage between the lobe and the follower (not follower and stem)

Fast forward a month to today, had another go at it. Decided to specifically ignore the manual and do it my own method. Started the car up and it's absolutely mint.

Basically, rather than trying to set an amount of drag on the guage, your better off it seems to use the screw to feel the setting just right.

So my process was:

Slip in feeler guage - easy light drag, but we know that's too loose now....

Slacken locknut

Unscrew adjustment screw

Screw it tighter using finger tightness only.

Once you approach the correct adjustment, there is a distinct change in the torque required (as instead of bending feeler guage and taking up slack, you are now beginning to compress guage/spring).

The moment the turning of the screw hits that resistance, which is very repeatable and distinct, I locked that in. At this point the feeler guage is quite hard to remove. Almost trapped infact. Much tighter than 'light drag'.

Will take it for a quick trip after dinner, but I think I've finally cracked it, a job I've done several times, but never been happy with.

Went with 6thou inlet and 7thou exhaust, so pretty tight. Might explain why I was struggling in the top end of 4th at thruxton, probably down on power!

Few random photos from the track day and rocker cover painting. Too clean, rest of the engine bay looks crap in comparison lolImageImageImageImageImageImageImage

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Scott560
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Post by Scott560 » Sun Sep 16, 2018 8:20 pm

Went for a quick spin - and all i can say is the car feels like a new car.

less hesitation at low revs (not that there was much)
much smoother pull to the red line
no harsh VTEC kick - its one smooth linear power band now
engine is nice and quiet at idle.
Exhaust seems quieter.

Overall very surprised that it could make so much difference, and annoyed that the manual does such a poor job of explaining the method.
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Post by crxdriver » Sun Sep 16, 2018 8:32 pm

After you tighten them they tend to go a bit tighter. Did you check after tightening that they was still OK? If you did i am really surprised that you had the troubles you did as ive never personally had any problems with setting at the workshop manual clearances. Ive done about 15-20 sets on Honda's over the years and all sounded sweet after, obviously the early b-series sounded a bit loud as they always to anyway due to LMA's.

Either way im glad to hear its running extra sweet! Enjoy.

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Re: Valve clearance adjustment I'm actually happy with.

Post by Scott560 » Sun Sep 16, 2018 9:40 pm

I used the special tool (kind of like a screwdriver through a socket) which allows the adjustment screw to be held still whilst tightening the locknut so it doesn't tighten.

I guess it's all down to the interpretation of light drag. The rocker is curved, and the cam is round. It's always going to drag, even lightly, regardless of what the clearance is set to. It's only when it nips up and pinches the feeler you know it's bang on.





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Post by crxdriver » Wed Sep 19, 2018 2:02 am

When its tightened you should still be able to get the feeler in there with minimal drag. If it does pinch it then its too tight. When tightened try to put the feeler in there again, if you cant its too tight. I use a spanner and screwdriver, you can still keep the screw from turning this way.

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Re: Valve clearance adjustment I'm actually happy with.

Post by Scott560 » Wed Sep 19, 2018 5:39 pm

I know what your saying, however the screw can be turned about half a turn at least and still end up with 'light drag'.

I've set to what seems sensible and I'm very happy with the new method... It makes sense tightening the screw by finger force only, until you hit the point at which your compressing things rather than taking up clearance.

I guess if you replace the manuals light drag with 'heavy drag' your probably closer to what's required.

Next meet we can all compare valve train noise lol.

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Post by Vtecmec » Wed Sep 19, 2018 7:16 pm

There's a considerable difference between the two......

Heavy drag.

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Light drag.

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Post by wurlycorner » Sun Sep 23, 2018 9:00 pm

Rocker cover looks absolutely stunning.
I haven't done valve clearances on an H22, but from doing them on other cars, it can indeed be difficult getting a decent clear pull on the feeler gauge due to valve stems being below the edge of the head, so the feeler gauge ends up being curved.
All makes it a very acquired touch kinda job.

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Post by Scott560 » Mon Sep 24, 2018 10:44 am

wurlycorner wrote:Rocker cover looks absolutely stunning.
I haven't done valve clearances on an H22, but from doing them on other cars, it can indeed be difficult getting a decent clear pull on the feeler gauge due to valve stems being below the edge of the head, so the feeler gauge ends up being curved.
All makes it a very acquired touch kinda job.
the prelude manual shows the clearance being set between the rocker and the camshaft directly (not the stem and adjuster as expected). the curved nature of both make me think the manual was slapped together using the light drag method wording which would be acceptable for stem based adjustments, but somewhat unrepeatable/unreliable for follower clearances (due to the large contact area).

Still, car is definitely running spot on - less induction noise too.

Only 100 more jobs to do and the car will be perfect!
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