Timing questions....

[Eric VerValin]

Ok, so we all know i'm swapping this short block out... Do I have to get the old motor / heads to TDC #1... or does it really matter? If I leave the heads intact, and keep the chains on the 'other side', aside from the 'fun' of turning those into place, will I be ok? I havent looked at the timing sprocket on the crank yet, as I havent pulled the oil pump and such yet, thats tommorow's project, But dosent that sprocket only fit one way onto the crank's key? I'm thinking when I put the old sprocket on the new block, and turn it into place I should be good? Maybe turn it over by hand a few times to make sure the marks keep lining up? I guess this is one more thing I thought about. I have my covers off, and just waiting to pull the bottom apart, and I guess this is my last snag.

Thanks, yet again..

 

[LJRuddy]

I cant really understand exactly what you are asking but it sounds like you are worried about getting the timing right when swapping parts to another engine?

If so, its really easy to line everything up.

-make sure the cam chains are lined up according to the little dot on each of the sproket. These should be in the middle of the brighter colored chain link I believe there should be 18 links between these dots on the cam chain sprokets.

-An easy way to make sure the cams are rotated to the TDC locations is to check the little notches on the cam shaft. You will notice 1 cube piece of metal on the side of the shaft. These pieces should be facing away from each other and lined up parallel from the surface of the heads.
EX: the exhaust cube on the rear head should be facing the firewall parallel to the surface of the head where the valve cover gasket rests. The intake cam on the rear head should be pointing towards the front of the car parallel to the surface of the head where the valve cover gasket rests.

-Install the belt pulley on the two camshafts. Line up the dot on each pulley to the line that is on the timing belt cover. These lines are at 12 o'clock.

-On the oil pump housing behind the crank pulley, you will see a small dot. You will also see a small dot on the timing belt pulley. These dots should be lined up together. If memory serves right, the dot on the oil pump housing is around the 5 o'clock position. This will ensure that the bottom end is at #1 TDC.

-Install timing belt and align the white line corresponding to the type of transmission you have to the dot on the front belt pulley. There are two white lines on the pulley and if you have an ATX, use the line for an ATX. Same for MTX. The reason for this (i guess) is that the ATX using a hydrolic tensioner where the MTX does not.

Your engine is now timed... in a nutshell

Recap:
1)time cam chains to camshaft sprokets
2)ensure the cam notches are parallel to the surface of the head and make sure that they are pointing away from the opposite cam on that specific head
3)install timing pullies onto the camshafts making sure to line up dots to the dots on the belt cover
4)time the crank to the dot that is located on the oil pump housing
5)line up timing belt to the to belt pullies ensuring that the correct line on the belt is being used. Again, use the line labled "MTX" if you have a 5spd or use "ATX" for your slushbox


I am writing this half asleep so if i missed something major, please note it!

good luck to ya


EDIT: Yes, the timing belt sproket that is on the crank only goes on one way per the keyway.

 

[Eric VerValin]

well that lower pulley i guess is my only question, since i wont be taking the chains loose, those should be easy to set, but the bottom one, i guess i was worried about... maybe getting it in 180 degrees outta whack.. thanks for the write up tho... goin back to the garage to play...

 

[Eric VerValin]

also.. just for ***** n giggles, i turned the motor over until it was at TDC and noticed my belt advanced a notch somehow, and at sometime... that belt only had maybe 10k miles on it, and it was fine after a month of chaning it, i pulld the top cover off and looked at it, and it was ok. But now it seems to have skipped. I cant imagine this is normal, and leads me to believe that I need a tensioner ?! Screw it, I think i'll just buy a new one and be done with it... (damn I say that alot rebuilding this thing....)

 

[pjtoledo]

also.. just for ***** n giggles, i turned the motor over until it was at TDC and noticed my belt advanced a notch somehow, and at sometime... that belt only had maybe 10k miles on it, and it was fine after a month of chaning it, i pulld the top cover off and looked at it, and it was ok. But now it seems to have skipped. I cant imagine this is normal, and leads me to believe that I need a tensioner ?! Screw it, I think i'll just buy a new one and be done with it... (damn I say that alot rebuilding this thing....)

The belt will not always contact the pullies on the same tooth, the belt sort of walks around the pullies advancing a bit on each revolution. For rechecking the timing, just loo at the dots on the pullies.

The crank rotates twice for each cam revolution, so ALL 4-stroke gas engines have their cams 180 out on every other revolution, sort of.



Perry

 

[Eric VerValin]

see thats what i thought, every other one, but yea its just odd to see it one tooth off. Guess its just where it lined up...