Re: '77 Chrysler 105 problems!!!
Background: Because you can get a large angular change with a very small linear change at top dead center, the factory developed a tool to check the timing at 32 degrees before top dead center. If it is set accurately at 32 before top dead center, it must be accurate at TDC so if the pointer marks do not match, you move the pointer to match them at 32 BTDC
So, what do you do if you do not have the tool? Simple!
1. least desirable method--Remove all four spark plugs. With the ignition off, insert a screwdriver into the top plug hole, touching the piston baffle, and rotate the flywheel. As the piston comes up to TDC, you will feel the screwdriver stop moving. Rock the flywheel back and forth a little to determine actual TDC. The disadvantage of this method is that it takes a keen sense of feel and even then, you can be off a couple of degrees. It is best if you close your eyes to minimise distraction while you are doing this and you need to practice a bit to develop the "feel"
2. 2nd method--most desirable. Take a depth gauge and insert it into the spark plug hole. Move the piston as near to TDC as possible and set the depth gauge. Reading does not matter, you just need to note it. Now, rotate the flywheel until the 32 degree mark is a bit before the pointer mark. Now set the depth gauge by adding to the original reading .XXX.This is 32 degrees BTDC and you turn the flywheel until it just touches the depth gauge. Set the pointer to the 32 degree mark on the flywheel.
Now, the reason I wrote .XXX is because I forgot the actual measurement. However, if you can get your hands on an Intertech manual, they give the actual measurement. As an alternative, KNOWING THAT THE CRANKSHAFT STROKE FOR A 105 IS 2.80 inches, a good math major can plug in the formula for you and tell you exactly how much 32 degrees rotation at TDC will give in inches---it's real small, something like .187.
And, of course, the most accurate method would be to use a dial indicator once you know the measurement.
This method works for ALL Chrysler engines from 75 to 140 HP and Force engines from 85 to 125 HP, with the following caveat: The Chrysler 125 and 140 (and possibly a few others) had a 2.875 stroke so the XXX measurement is larger. I believe--am not sure-- that some Force 125 had a 2.80 stroke and some had a 2.875. So, you need to measure it before taking a setting number.
