Mitsubishi 4 cyl SOHC Camshaft Dialling

Okay you have a camshaft and you want to install it into your engine. We will do a separate guide to the actual fitting at a later stage. This guide is for the actual dialling in of the camshafts. Very important as the wrong setting up of a camshaft severely affects the idling and drive ability of the vehicle. There are many ways of doing this and many people want to know the lift / duration and cam opening / closing times etc. This is all too hard way of doing it.

RPW instead uses the following method called the "Centre Line Method" by working off the centreline of the camshafts. Is a lot easier and we have been doing this successfully for a number of years. We hope this makes life a little easier for you to do as well. We will try to be as specific as we can with detailed photos. RPW takes no responsibility for this guide and is not liable for any wrong fittings, accidents and anything relating to this information. Any reference to this information is done at the users own risk.

Installation Guides

(A) Tools Required ..... - You will require the following tools.

  1. Dial wheel / cam wheel to be fitted to the crankshaft of the engine.
  2. Dial guage with 6" extension with magnetic base to affix to top of cylinder head.
  3. Socket set with 6" extension
  4. Screwdriver set
  5. Allen key set (If you have RPW Vernier Camshaft Gear)
  6. Small hammer
  7. Small container to place all screws and clips so they don't get lost (Trust me on this)

(B) Step 1 ..... - Removing Rocker Covers

1. Ensure vehicle engine is turned off (Obvious we know), out of gear and the handbrake is on. Preference is on a flat driveway as at some stage the vehicle will have to have the handbrake turned off and on again. Chock wheels if possible.

2. Remove rocker cover and all items across the top of the motor. If you are having difficulty with any of this stop now, refit everything up and take the vehicle to someone who knows what they are doing. It is a lot cheaper in teh long run.

3. Get the crankshaft on top dead centre on number one cylinder and ensure that the rocker gear is on top dead centre number one, not number four cylinder.

4. Fit your degree wheel to the crankshaft and affix a marker to where zero degrees is on your crankshaft pulley. This may necessitate removal of your front pulley off your engine. Ensure you get the car on TDC number 1 before removing the pulley.

5. Once this is done (It is assumed at this point your new camshaft and cam gears are already fitted to the vehicle), we are now ready to find out where the timing of your camshaft is.

(C) Step 2 ..... - Working out where you are now - exhaust lobe

1. Turn the motor over until number 1 cylinder exhaust lobe is at its highest lift point IE when the exhaust valve is depressed the most. At this stage fit the magnetic base dial gauge to the top of the cylinder head, and set it up so that you are in the middle of its adjustment with 50% loading. Ie if you have four revolutions of movement, then set it so that you are on the 2nd revolution of movement.

2. Now turn the motor backwards half a revolution and zero your dial guage again.

3. Turn your motor forwards until reading off the dial gauge, you have reached the maximum lift point / max depression on the exhaust valve.

4. You will note that there is a degree of movement, usually 10 degrees of where you can continue to turn the motor without the dial gauge moving. You can either work on the halfway point, or the start and finish of this movement, as long as you use the same reference point on all measuring.

5. Using whatever method described above, mark the position on your degree wheel that this max lift point is. Best to write it down on a piece of paper. It will be something like for example, 110 degrees BTDC etc.

(C) Step 3 ..... - Working out where you are now - Intake lobe

1. Repeat the above method but this time on number one cylinder, perform it on the intake lobe.

2. Using whatever method described above, mark the position on your degree wheel that this max lift point is. Best to write it down on a piece of paper. It will be something like 120 degrees ATDC etc.

(C) Step 4 ..... - Working out the centre line of your camshaft.

1. Now you have your figures, and for ease of understanding lets say that the max lift point of your Intake lobe is 120 degrees ATDC and the Exhaust lobe max lift point is 110 BTDC to save confusion.

2. To work out the centreline of your camshaft the formulae is Exhaust Lobe Max lift point minus Intake Lobe Max Lift Point. This would then work out

110 Deg BTDC minus 120 Deg ATDC which woudl result in the camshaft centre line being 10 Degrees ATDC. Therefore the camshaft is at this time running 10 degrees Advanced.

3. Now that you know where your camshaft centre line is, it gets really easy.

(C) Step 5 ..... - Adjusting your camshaft

1. Going on the principle that the camshaft is currently 10 degrees advanced and we want to set it to true zero, you firstly adjust the cam gear to move the camshaft the desired direction.

2. From here choosing either the intake or exhaust lobe position, repeat the finding of your max lift point. Mark the position again and see how far you have moved the camshaft. If you have moved it too much then whilst you are this point, adjust it to where you want it and check again.

3. Remember this is a circle so whatever amount of degrees you wish to move it, divide it by half. For example we want a 10 degree movement in total here. So that means we need to reposition the max lift point of the exhaust lobe to 115 degrees BTDC as this will then relocate the intake lobe to 115 degrees ATDC. I hope you can see how this works.

4. Once you have set the camshaft centreline to zero degrees, you can now choose to either leave it there, advance or retard your cam timing to whatever your desired position. We recommend once you have found the zero point, mark the cam gear so that you can go back to that any time without having to do all this work again.

5. This can also be done without having any of the rocker gear fitted and reading directly off the camshaft to the same degree.

We hope this helps with the fitting and dialling of the camshaft into your engine. Note this method does not require any camshaft specifications, because you are working directly off the centreline of the camshaft, which allows you to do so easily without having to know any technical knowledge.

Copyright © 2020 Racing Performance Works. All Right Reserved.