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Honda V-4 Magna/Sabre
|Courtesy Dodge Racing & Promotions
Huntersville NC 28708
|Dave Dodge has generously agreed to publish his time tested valve adjustment procedure. V-4 valve adjustment has been the subject of dispute for many years. Below is a procedure, developed by David Dodge, that eliminates the guesswork and provides a reliable, accurate adjustment, without the use of the cam tool.|
|V-4 Performance Products|
A) Remove all of the spark plugs and left side alternator cover.
B) Rotate the engine at the crank nut (alternator) in a clockwise rotation (only) while putting your finger tightly over the #1 plug hole (left rear). When the engine begins compression stroke on #1 you will feel pressure against your finger. Once you begin to feel pressure, slowly rotate crank to align "T-1" index mark of the rotor with the case half alignment position. This is your starting point at cylinder #1NOTE: The cam lobes on the rear cylinders Will point away from each other at TDC compression. The cam lobes on the front cylinders will point up and slightly towards each other when timing marks are aligned The marks on the cam sprockets will also line up with the gasket surface on the head when the cams are in the correct Inca f/on.
C) I personally do not use the factory Honda tool. I instead (beginning with #1, lobes pointing away from each other) insert a .003" feeler gauge between the cam lobe and rocker arm pad. I then turn the adjusting screws until they lightly touch the ends of the valves and tighten the lock nuts. This method will give you a snug .003" clearance at the cam, and .005" clearance at the valve. The recommended .004" at the valve is too tight.
D) Slowly rotate crank (clockwise from #1) with finger over #2 plug hole until 'T" rotor mark aligns with case mark. You should have felt the pressure against your finger. The lobes will be pointing up and slightly towards each other and the cam sprocket marks aligned with head surface. Adjust valves.
E) Slowly rotate crank to #3 cylinder and follow alignment procedure "C"
F) Slowly rotate crank to #4 cylinder and follow alignment procedure "D"NOTE: After adjusting each cylinder check for proper clearance at each valve. After adjusting all of the valves, rotate engine for a couple revolutions and recheck all clearances again at TOO locations (just to make sure). When you are satisfied that all clearances are set, the locknuts must be torqued to 14 ft. lbs.
What is the cam tool?
The cam tool is a part supplied by Honda, that has a 'thumbwheel' screw assembly at the top. Its function is to hold the cam up in the journal while adjusting the valve. This was supposed to simulate actual operating conditions.
Other Valve Adjustment Info From The V65 Society
Valve Adjustments - In Practice
The following was taken from the V65 Society Newsletter. It describes the basics of valve adjustment.
Also, be sure to use TWO sets of feeler gauges... one for each of the arms of the twin arm rockers. It's very important to have the appropriate feeler gauge under each arm when adjusting... using only one will yield inaccurate results.
One thing remember when adjusting valves, is that it is VERY easy for something to accidentally slip and fall down the cam chain tunnel. I know of two incidents where small tools found their way down into the oil pan via this hole. The fact that your fingers will be slick with oil while doing this work makes matters worse... it's very easy to drop things. Tip: attach a long piece of wire to any small tools that might possibly fit down the cam chain pit.
The oil pan cannot be removed without dropping the exhaust system, which requires the removal of nuts/studs which are often frozen, etc. Though it is a real trick, it is possible to lower the oil pan a tiny amount without removing the exhaust, just enough to fish out any small lost items with a piece of wire, magnet, etc.
In order to set the correct position of the crankshaft, and thus cams, for proper valve adjustment, the alternator cover must be removed to gain access to the flywheel.
Tip: when installing a new alternator cover gasket, apply a tiny bit of gasket tack to the cover side, but then apply a thin film of high temperature anti-seize lubricant to the engine side. The next time you remove the cover, the gasket will remain intact, and be reusable. I've gotten over four cover removals out of one gasket, zero leakage.
Though most mechanics are able to torque things pretty accurately by "feel", I recommend using a torque wrench on the valve adjusting lock nuts. The torque on these nuts is critical... too loose, the adjuster may loosen up, too tight, you can strip the parts. Keith M. experienced an adjuster nut that backed off, and it ultimately resulted in four bent valves. Since there's not much clearance between the frame and the rearward head, it's necessary to use a relatively small torque wrench with a 1/4" drive, or a very small 1/2" drive wrench and 1/4" adaptor. Even then, you may need to customize the length of a 1/4" drive 10mm socket and/or socket extension to allow fit.
Removing the rearward valve cover is tricky. The top part of the two-piece cover must be removed. The bottom part, which is more difficult to remove, can be left in, since it is possible to simply shift it up and out of the way of the adjusters. Ray T. suggests that the PCV air box (breather separator) on Sabres can be removed without too much trouble, to allow easy removal of the valve cover bottom half.
As Bruce B. points out, the plastic heat shield which exists between the coils and rearward valve cover is a real pain to remove and replace. Bruce recommends to remove this plastic shield just once, and discard it. On a V45 I once owned, I cut and modified the heat shield to make removal/replacement easier. Incidentally, the shield must be removed from the right side of the bike. Be careful not to bend the solid clutch hydraulic line or stress the wire harness.