ultimate lurker

Just for reference, I never let my exhaust valves get out of spec (and they never have been when checking over 25k miles). However, I adjust my intake valves a little tighter than spec (about 2 thousandths). It has the effect of adding more duration and lift. Since intake valves are subjected to the same heat and stress that exhaust valves are, it really isn't a big deal.

This has been an old Honda tuner trick for years and does work. I don't trust my butt dyno, but when I adjusted them last week I liked the feel. I'll get the car back on the dyno this week and see if power improved.

UL

Gernby

[QUOTE]Originally posted by ultimate lurker
[B]Just for reference, I never let my exhaust valves get out of spec (and they never have been when checking over 25k miles).

Prolene

[QUOTE]Originally posted by ultimate lurker
[B]Just for reference, I never let my exhaust valves get out of spec (and they never have been when checking over 25k miles).

S2K2GO!!!

One thing I do is carefully measure both the before and after clearances when I adjust my valves, and record these in my maintanance log. You can actually estimate the .000X (ten-thousandths) position with amazing accuracy using ordinary feeler guages by noting how hard it is to insert one leaf compared with how easy it is to insert the next size down. Why would this matter? not at all, so far as engine performance is concerned, but the record allows you to sum the adjustments you've made over time for each valve, making it far more likely to pick up an impending burnt valve(repeatedly too tight) or failing roller/follower(repeatedly too loose), seat working out of position(loose), carbon buildup(loose), etc. Admittedly, this has more value on engines with longer valve trains, like the airplane engines I started doing this on years ago, and for which I have averted at least two failures. Still, not a bad thing and easy.

peterpan

[QUOTE]Originally posted by gernby
[B]I forgot to mention that I had also adjusted a friend of mine's '02 S2000 valves.

peterpan

[QUOTE]Originally posted by ultimate lurker
[B]Yep, I'm pretty sure now, 2002's make more power.

I've dyno'd 3 stock 2002's on my dynapack.

smyroad

Thanks for the heads up. I haven't adjusted mine yet, but I would have used the rocker-arm to cam-lobe approach. Thanks!

TJ Stooker

So is there a consensus on optimum valve adjustment settings?

Helm's lists the spec as Intake: (.008 - .010 in) and Exhaust: (.010 - .011 in)

I use my '02 for autocross and want the most low end possible within spec. Should there be a difference within the same cylinder?

The valves are being adjusted this week and I would like specific feedback on settings.

THANKS!!!

-Derek

Gernby

I wanted to report a surprising effect of the valve adjustment. Before I corrected my clearances, I was consistently getting between 175 and 185 miles per tank (for several thousand miles). This is daily driving OFF of the highway with the top down and the A/C off. This mileage was VERY consistent. After fixing my valve clearances (as described above) my mileage has increased to between 190 and 200 miles per tank (for several thousand miles).

Before anyone starts lecturing me about scientific error and things, let me just say I KNOW. These are not scientific measurements, but I feel that they are significant observations. I drive very aggressively (downright dangerous) all the time, so I'm surprised there isn't more fluctuation in my mileage. I am also surprised that my mileage hasn't gone DOWN as it gets cooler.

marcucci

I'll lecture you on scientific things- mileage INCREASES on most motors as temps get cooler, since the intake air charge is denser and the car will make more power. I know that most engines richen the a/f mixture with cooler COOLANT temps (and maybe even intake air temps) but it has been my experience that mileage goes up. I would assume because the engine/coolant temp is regulated fairly well, and the only "real" change as far as the ECU is concerned is that the intake air charge is cooler.

For instance, my truck which normally gets about 17-18 mpg in my normal commute now gets 19-20 mpg (all consistently) with the 20 or 30 degree cooler (than summer) weather we've been having here in NoTx.

What's your executive summary on what your valve clearances WERE before the "fix?" I don't doubt it would have an effect on power which would have an effect on your throttle position (to make up for it) which would affect mileage, though.