Setting the camshaft timing

[powersmythe]

One of the frequently misunderstood topics of the Ford 300 six is the camshaft timing.
The camshaft timing's most important function on the 300 six is to determine the minimum pump gas octane that the engine can run on without detonation.

The second reason for checking the camshaft timing events is to verify the camshaft specs.

There have been too many cases where an engine build was expected to run on 87 octane pump gas but needed 91 octane to prevent detonation.

A degree wheel and dial indicator with a magnetic base stand are the tools needed to check the camshaft timing events.
An 11" degree wheel is sufficient.
The wheel and dial indicator are relatively inexpensive.

First step is to zero the degree wheel so that the pointer is at TDC on the wheel when the #1 piston is at TDC.
A pointer can be made from coat hanger wire that bolts to one of the bolts holes for the timing cover and loops around to the degree wheel.

If the cylinder head is on the engine, then you will need to use an 18mm adjustable stop that screws into the spark plug hole.
A stop can be made by removing the porcelain center of a spark plug and threading the spark plug base for a bolt.
If the cylinder head is not on the block, then you can make or purchase a bar that bolts across the top of the cylinder with a bolt that screws down the middle of the cylinder bore.



Before you install the stop, get the #1 piston as close to TDC as possible and set the pointer to TDC on the degree wheel.
After the stop is installed, carefully turn the crankshaft one direction until the piston rest against the stop and note the pointer reading on the wheel.
Then turn the crankshaft in the other direction until the piston rest against the stop and note the pointer reading on the wheel.
Add both readings and divide by two.
Then readjust the pointer to that reading on the wheel with the piston against the stop.
To verify the wheel is at TDC, turn the crankshaft the other direction until the piston is up against the stop.
The reading should be the same in either direction.

As an example, If the piston stop is stopping the piston .100" from TDC, then the crankshaft is 16 degrees before and after TDC in either direction against the piston stop.

If the head is off, you can also use your dial indicator instead of a piston stop.
Locate the dial indicator on the center of the piston over the wrist pin so piston rock does not affect the readings.
Bring the piston to TDC and zero the dial indicator. You will notice there is a few degrees of piston dwell time as the crankshaft crosses over TDC.

We usually locate the piston .050" from TDC.
The crankshaft needs to push the piston up into position from both directions rather than pulling the piston down from TDC.
This prevents the connecting rod bearing clearance from creating error.
Turn the crankshaft CW until the dial indicator reads .050" from TDC and note the reading on the degree wheel.
Then turn the crankshaft CCW until the piston returns to .050" from TDC and note the reading.
Add both readings and divide by two.
Use that calculated point to set the reset the pointer on the degree wheel.
It should be close to 11 degrees before and after TDC.

Once you have the degree wheel zeroed, set the crankshaft to TDC and bolt a pointer to the back of the crankshaft.
Then mark the pointer location on the block.
You can use this to set the crankshaft to TDC to check the timing of the harmonic balance when it is installed so you can get the correct ignition timing.

[powersmythe]

Camshaft Timing:

The camshaft should be timed using the .050" duration method.
If the .050" opening and closing points shown on the cam card correspond to the readings you are recording from the degree wheel, then the camshaft is timed correctly, and the camshaft specifications are also verified by the readings.

If you use the Lobe Center method, you are assuming that the lobes are symmetrical and that the actual cam specs are correct which may or may not be true.

You can use a pushrod as an extension between the dial indicator and the lifters.
Zero the dial indicator when the lifter is all the way down on the heel of the cam.
Then turn the crankshaft CW until the dial indicator reads .050" and record the wheel reading.
Continue turning the crankshaft CW.
The dial will go past max lift and down. You can record max lift as you swing past it.
When the dial reads .050" from the bottom, record the wheel reading.
It is IMPORTANT that the crankshaft is always being turned clockwise when taking degree wheel readings, so the timing gear clearance between gears doesn't introduce an error.
If you accidentally go past a .050" point on your dial, back the crank up CCW and come back into the .050" reading CW.

Once you have the intake opening and closing points and the exhaust intake and closing points, you can compare them to the cam card opening and closing points to determine if the cam timing is correct or if the timing needs to be changed.
You can also verify the .050" cam durations, cam lobe lifts and Lobe Separation Angle to see how close the actual cam specs are to the cam card specs.

If the cam timing is off and needs to be changed, there isn't any multi keyway gears sets available at this time.
Straub Technologies is working to provide a multi-keyway gear set.
We are presently using offset keys in the camshaft gear to move the camshaft timing.
Mr Gasket makes an offset key that is used in the camshaft gear.
The Mr Gasket 987G will move the cam 4 crankshaft degrees and the Mr Gasket 988G will move the cam 8 crankshaft degrees.

The Intake opening and the Exhaust closing points are referenced to Before and After TDC so you will use the outside circle of numbers on the degree wheel.
The Exhaust opening and Intake closing points are referenced to BDC and uses the smaller inside circle of numbers on the degree wheel.

[Henry W]

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[Henry W]

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[Henry W]

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