Super Street Network

 |   |   |  Valve Adjustments - Get 'EM Down Cold

Valve Adjustments - Get 'EM Down Cold

Bona Fide Tech Tips

Robert Young
May 1, 2008
Htup_0805_01_z+valve_adjustments+tech Photo 1/1   |   Valve Adjustments - Get 'EM Down Cold

Embrace Your Inner Noob
Adjusting valve clearances is simple, right? They can be, as long as you follow what Honda has to say about them. If there's one thing Honda says to do when it comes to adjusting those valves, it's to do them when the engine is cold. Look at any Honda service manual and they'll all tell you as much. Unfortunately, engines are often blazing at full temperatures when the thought of a valve adjustment occurs, which makes attempting to adjust those tappets, despite the heat, all too tempting. Stop. Have a bit of self-control. Let that cylinder head cool off before doing anything; the results will be better for it. Metal objects like camshafts, rocker arms, tappets and even the cylinder head expand and contract as temperatures change. When they're hot, they get bigger, reducing the clearances between parts. Oftentimes camshaft manufacturers and even service manuals will offer recommended valve adjustment clearances to be used during hot conditions, but this just isn't the right way to do it. A typical Honda cylinder head reaches temperatures above 200 degrees F. Who's to say what temperature it's at by the time you reach the last adjuster? It'll inevitably be less than when you started. Remember, as the top end and valvetrain cools, clearances change accordingly, slightly, but enough to matter.

Do yourself a favor and allow the engine to cool down some prior to adjusting those valves. Point a high-powered fan toward the cylinder head until it drops to, at most, 100 degrees F or is warm to the touch. With the cylinder head cooled down, follow the service manual's maximum clearance specifications and adjust to the higher number. Erring on the high side helps put the valves in the middle of the range, as if the engine were stone cold. Don't have a service manual? Valve clearance specifications can be found underneath the hood on the emissions label. Scraped the label off, got a carbon-fiber hood? You can always purchase the label at your local Honda dealership.

It's important to note here that if you're trying to correct a valve clearance-related problem, like excessive valve noise, idle misfiring or slight power losses, don't adjust the valves unless the engine is completely cooled down. Allow the car to sit overnight. Excessive valve clearance causes noise and insufficient valve clearance may cause misfiring, even permanent valve damage so it's important to get it right.

By Robert Young
15 Articles



The time to stop thinking of wheels as nothing more than some sort of aesthetic improvement is now.
Aaron BonkNov 27, 2015
In no particular order, here are the top Honda products we saw at the 2015 show.
Justin BannerNov 23, 2015
With the winter weather quickly approaching, it’s time to take the summer tires off and load up on some extra tread.
Ryan JurneckaNov 13, 2015
Hunting down the best and newest aftermarket parts for the tuner scene's latest obsession.
Jofel TolosaNov 5, 2015
It hasn't been an easy road to our annual Super Lap Battle time attack, but that's just part of the fun of building a capable track car!
Mike SabounchiOct 30, 2015