How many revolutions does it take ...

[FFRSpec72]

So how many revolutions does it take for the timing belt marks and the cam/crank marks to all line up, 100? 200? never ?

[Bob_n_Cincy]

So how many revolutions does it take for the timing belt marks and the cam/crank marks to all line up, 100? 200? never ?

The crank shaft pulley has 24 teeth. The belt has 281 teeth.
So after 12 crank revolutions, the belt mark is off by 7.

The least common multiple of 7 and 24 is 168.
I think 12 x 24 =288 crank revolution to bring all the marks back together.
I loved story problems in school.
Bob

Edit: corrected my math

Edit: Just spin it backwards the same number of revolution the engine has run forward.

[billjr212]

Bob - I think you've either got a typo or your math is off. After 20 revolutions of 24 teeth, you've moved 480 teeth, or roughly 1.7 spins of the full belt, leaving you quite a ways off the original mark.

[billjr212]

Assuming the 24 and 281 figures are accurate, you need 24 x 281 revolutions to match up, or 6,744. Since 281 is a prime number, I don't believe they'll match up before then.


Funny you started this thread, I was just wondering this the other day, but didn't bother to to the math.

[billjr212]

Sorry - i butchered that - it's 6,744 teeth need to move for them to match up, meaning 281 revolutions of the crank.

[FFRSpec72]

I only have 280 more cranks to verify !

[Bob_n_Cincy]

I only have 280 more cranks to verify !
I'm waiting
Quicker method is to put engine at TDC and take off belt and re-install.

[FFRSpec72]

I'm waiting
Quicker method is to put engine at TDC and take off belt and re-install.

I did that 2 times (had to verify the verification), not as fun as seeing how many revolutions is takes though

[ssssly]

Edit: Just spin it backwards the same number of revolution the engine has run forward.

Do not turn the crank backwards to verify timing.

If the timing is off, you will bend a valve.

Just take the belt off and redo it if you are in doubt. Only takes 10 minutes.

[Ironhydroxide]

dont spin it that many times... that's illogical. you only need a few spins to make sure all the slack is in the tensioner then Check the timing marks on the crank with the mark on the sensor housing, then check the cams for proper placement...