Valve Clearance Adjustment

Dave Dodge Method

Over the years I have developed a method of adjusting the valves on V-4's that is accurate and quick. The crank and rotor position is the same using the rotor TDC marks. Make sure that the cylinder you are adjusting the valves for is on TDC compression stroke. On the rear cylinders the cam lobes will be pointing AWAY from each other, and on the front cylinders the lobes will be facing UP and slightly towards each other when the particular cylinder to be adjusted is at the correct position.

Loosen and back off the adjusting nuts on the intake and exhaust rockers. Place a 0.003" feeler gauge between the cam lobe and rocker arm. Snug down the adjusting screws (with your fingers) until each screw just touches the valve tip, then move the feeler gauge back and forth to make sure there is drag (not tight/not loose) and tighten the nuts with a wrench. Now recheck the clearance at the valve with a 0.005" feeler gauge. The feel should be a snug 0.005" or a loose 0.004". Re-adjust the screw if you don't get this feel on all four valves. Use same procedure on remaining three cylinders.

There is a 1.5:1 rocker arm ratio, so 0.003" at the cam gives you a snug 0.005" at the valve. The 0.005" should go in snug, but move in and out without bowing the feeler. Once the initial setting is done with the 0.003" and removed, it wont go back in. This procedure reduces the risk of uneven rocker adjustment. Once you get the feel of a snug 0.005" clearance, you will find you have proper setting for long cam life and minimal (if any) clatter.

IMPORTANT: I always torque the adjusting nuts to 15 ft-lbs. Tighten the nuts with a wrench enough so they wont come loose, then rotate engine until rocker arm depresses valve about half way. This will allow room for the torque wrench and the pressure against the adjusting screw will keep it from turning while you are torqueing.

Robyn Lander's Method

Robyn Landers has an illustrated, step by step guide at: V4 Valve Adjustment.

Rotating the Cams

Rather than tediously lining up the timing marks, you can reconnect the wiring plugs that you disconnected while removing the heat shield and rear cylinder cover, so that the starter motor will work. Flip the kill switch so the engine won't actually start, then blip the starter so that the cam lobe on the *opposite* end of the camshaft you're working on is at full lift.

The cam profiles on the Magna/Sabre are not very radical, so you have a fair bit of leeway as to where this occurs. Now, on the end of the camshaft you're working on, install the special tool. Both ends of the camshaft are now being pressed up against the camshaft holders, so the camshaft won't be tilted. The long flat feeler gauges are flexible enough to be easily bent to ensure there is no binding when testing the clearance. ("Bent" doesn't mean putting a sharp crease in them to make an angle, just pressing down a little to curve it so that it goes straight in between the adjusting screw and valve.)

Use two gauges at once, one under each side of the follower. When the clearance is correct, the gauge should be moveable with a slight drag, whereas the next size up should not go in at all, unless you really force it, in which case you're fighting against the valve spring. Even after carefully setting the valve clearance, there may still be a little audible ticking, especially before the engine fully warms up.

As related on Robyn Landers's web site, some later engines had the cam bearings line bored. These can be identified by half-circle plugs in the heads where the boring tool went in. Clearances on these engines are tighter so supposedly you don't need the special tool to adjust valve clearances. You can check out valve noise with an automotive stethoscope, or the poor man's substitute: a long screwdriver held with the tip pressed into the hex socket in the head of the rocker shaft and the other end pressed against your ear.

VF500 Valve Adjustment Tools

The VF500 engines use a 3mm square end tappet screw. Both the Honda and Clymer manuals specify a part number for a valve adjusting wrench which is no longer valid on Honda's order system. The invalid part number is 07708-0030400, the correct part number (as of 10/2000) is 07908-KE90200.

In the interest of frugality, however, this is a cheaper alternative: a square head drywall screw and a handle made from a door knob or small block of wood.

Tips

After setting the valve clearance, rotate the engine until the adjustment screw rises in the head. The pressure from the cam keeps the screw from turning as you tighten the adjustment nut. This also allows more clearance for use of a wrench (torque or otherwise).

After tightening the adjustment nuts, rotate the engine through two combustion cycles to "set" the valves and measure the valve clearance again. If off, set again. Rotate and repeat. If they are still off, sometimes they move and you have to initially set the clearance tighter or looser to get a good "final' clearance.