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Honda V-4 Magna/Sabre
Camshaft Installation and Degreeing

Courtesy Dodge Racing & Promotions
16503 Glenfurness
Huntersville NC 28708
drp123@mindspring.com

Dave Dodge has generously agreed to publish his cam degreeing procedure for the Honda V-4 engines to benefit SabMaggers everywhere. 

V-4 Performance Products

Installing cams in a Honda V-4 is probably one of the most time consuming and confusing tasks you can do on this engine. It is also one of the best kept secrets. Many advantages can be gained by degreeing your cams, including changes in performance characteristics to increase bottom-end or top-end power, increased valve to piston clearance, or just blueprinting the lobe center settings to be the same for all four cams. Basically, on a V-4 you are installing cams in two different engine configurations because of the way the heads are mounted, and the effect of engine rotation. Cams should be installed in each head separately, and treated as two independent installations.

We are going to explain the race industry standard method of setting the cams using the 'Lobe Center' method. High performance camshafts come with a timing card. The specs on the card are developed on a machine that does not have any variables such as stretched cam chains, rocker arm play, or clearances that are found when the cams are installed into the engine. Vary rarely will a cam install exactly at the opening and closing numbers shown on the card. Degreeing the cams in by Lobe Center is the only accurate way to install camshafts in an overhead, multiple cam engine. You are actually setting the cams, using a formula that determines where the cam is at full lift in relation to crankshaft position. This averages the opening and closing points, but positions the cams in perfect relation to the crank eliminating any variables.

TOOLS NEEDED:

1) Degree Wheel - with TDC and BDC markings showing zero
2) Degree Wheel Pointer - can be a piece of wire mounted to the case and bent to read wheel numbers
3) Dial Indicator and Base - 1 'travel indicator and a magnetic base work best
4) Positive Stop - threads into plug hole to stop piston before TDC for setting degree wheel

INSTALLATION STEPS
Because you are using two different TDC marks to install the cams in the front and rear heads, it is best to start with the rear head. While installing the cams in the rear head you should remove the cam chain tensioner from the front so the cam chain does not get tangled, easing the ability to rotate the crank.

Rear Head

1) Loosely mount the degree wheel to one end of the crank at approximate TDC. Install the pointer to the case and bend it over degree wheel face. All crank rotating should be done from the opposite end of crank to avoid accidental degree wheel movement.

2) Make sure that the piston of cylinder #1 (left rear) is backed down about 40º before TDC. Install the positive stop tool in the spark plug hole. Slowly rotate the crank in one direction until the piston touches the stop and make note of the number shown on the degree wheel. Slowly rotate the crank in the opposite direction until the piston touches the stop and make note of the number. Move the degree wheel and repeat this procedure until you get the same number of degrees going in both directions. When the positive stop is removed you will have exact TDC when crank is rotated to TDC on the degree wheel.

NOTE: Be certain that the cam chains are not binding while rotating the crank.

3) Mount the cam sprockets onto the rear cams. If slotted (adjustable) cam sprockets are used, only install with one top bolt on each cam. Fully advance the exhaust cam (top of cam flange toward rear) in slot, and fully retard the intake cam (top of cam flange toward front) in slot. This will give you maximum valve -to-piston clearance and Lobe Center to avoid damage while rotating the crank.

NOTE: The rounded side of the cam sprocket [aces against the cam mounting surface.

4) With crank at TDC on #1 cylinder, install the rear cams with the lobes facing directly away from each other and the 'LINE' marks on the sprockets aligned with the head cover gasket surface. Be certain to remove the cam chain slack while installing the cams. Once the cams are installed and marks aligned, finish the assembly of the head, torque the head and cam cap bolts, and set the cam chain tensioner. Squirt oil on cam lobes and rocker arms and rotate the crank (normal direction of rotation) two complete revolutions and back to TDC. Check again to make sure your marks are aligned and that the lobes on #1 cylinder are facing away from each other.

NOTE: Make sure the cam chain tensioner blade is seated into the receiver inside the case. If blade is not seated, the tensiot7er will not work and grind against the cam chain.
Finger tighten the rocker arm adjusting screws against the valve tips to zero the valve lash and snug down the lock nuts. Mount the dial indicator and base to a solid location. The top cam chain guide works well. The tip of the dial indicator should rest on the spring retainer at the same angle as the valve, making sure you have unrestricted travel in both directions. Set the dial indicator to read zero.

6) Rotate the engine in the normal direction of rotation until the dial indicator reads .040" of valve lift and note the number on the degree wheel. Continue in the same direction until the dial indicator reads .040" before the valve closes. The smaller dial on the face can show you where .040" lift off seat occurs.

LOBE CENTER FORMULA:

Opening Degrees + Closing Degrees + 180º = XXXº (duration @ .040" checking lift)

Divide the Total by 2, then subtract the smaller number of opening or closing. End number is your Lobe Center.

EXAMPLE: DRP-30750 Intake Cam

Opening 11º BTDC + Closing 51º ABDC + 180º = 242º duration at .040" checking lift

Total 242º / 2 = 121º minus 11º (smaller number) = 110º Lobe Center

To adjust the Lobe Center, the cam is moved in the cam sprocket slot. When the opening number gets bigger the closing number gets smaller and visa-versa, so you are subtracting a different number to change Lobe Center.

For a higher Lobe Center:

Retard the Intake (making the opening number smaller)
Advance the Exhaust (making the closing number smaller)

For a smaller Lobe Center:

Advance the Intake (making the opening number larger)
Retard the Exhaust (making the closing number larger)

NOTE: Intake cams must open BTDC and close ABDC. Exhaust cams must open BBDC and close ATDC. If not remember to work in negative numbers, while checking, until settings can be corrected.

Front Head

1) Make sure that the piston of cylinder #2 (left front) is backed down about 40º before TDC. Install the positive stop tool in the spark plug hole. Slowly rotate the crank in one direction until the piston touches the stop and make note of the number shown on the degree wheel. Slowly rotate the crank in the opposite direction until the piston touches the stop and make note of the number. Move the degree wheel and repeat this procedure until you get the same number of degrees going in both directions. When the positive stop is removed you will have exact TDC when crank is rotated to TDC on the degree wheel.

2) Mount the cam sprockets onto the front cams. If slotted (adjustable) cam sprockets are used, only install with one top bolt on each cam. Fully advance the exhaust cam (top of cam flange toward rear) in slot, and fully retard the intake cam (top of cam flange toward front) in slot. This will give you maximum clearances and Lobe Centers to avoid valve damage while rotating the crank.

NOTE: The rounded side of the cam sprocket faces against the cam mounting surface.

3) Install the cam chain tensioner if previously removed. Make sure the cam chain tensioner blade is seated into the receiver inside the case.

NOTE: If blade is not seated, the tensioner will not work and grind against the cam chain.

4) With crank at TDC on #2 cylinder, install the front cams with the lobes facing up and slightly towards each other and the 'DOT' marks on the sprockets aligned with the head cover gasket surface. Be certain to remove cam chain slack while installing the cams. Once the cams are installed and marks aligned, finish the assembly of the head, torque the head and cam cap bolts, and set the cam chain tensioner. Squirt oil on cam lobes and rocker arms and rotate the crank (normal direction of rotation) two complete revolutions and back to TDC. Check again to make sure your marks are aligned and that the lobes on #2 cylinder are facing up and slightly towards each other.

NOTE:   Firing order is critical and should be 1-2-3-4. Be certain that the cams in #2 (left front) cylinder are installed 270º after #1 (left rear) cylinder has compression stroke. Check firing order while rotating crank (normal direction of rotation) and using your finger over the spark plug hole to feel compression. Make sure that cylinder #2 tires 270º after #1. If it doesn't the cams are 180º out and must be corrected.

5) Degree the front cams using previous steps 5 and 6 along with the Lobe Center Formula above.