This past weekend I changed my timing belt, and when I put everything back on and drove the car, it felt really slow. So I checked the cam gear timing, and I noticed that when the crank pulley is at TDC, the 2 marks on the cam gears that are supposed to line up with each other,are off by about 2 millimeters (left cam gear mark is slightly under the midway point, and right cam gear mark is slightly over the midway point).

When I line up the cam gears so that the markers are in the correct position for TDC, the crank pulley TDC mark is about 2-3 millimeters to the left of where it should be.

I dont think that the cam gears are off by a tooth, because the two marks on the cam gears arent off by that much, but they still dont line up exactly!

Do you guys have any idea what the problem could be?

 

You know they're not only supposd to line up with each other, but they're supposed to line up with a straightedge laying across the shaft centers. As well as the corresponding marks on the far outside of each sprocket. Right?

2mm is almost 1/2 a tooth? (I don't remember.) If so, try moving it so it's 1/2-tooth off in the other direction? Mine isn't perfect, but it's less than 1/2 a tooth.

But FIRST, how's your spark timing?

 

well about 2 months ago I adanced my ignition timing by about 2-3 degrees...could that be why it is still off ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Eclipse spanker &raquo;</TD></TR><TR><TD CLASS="quote">well about 2 months ago I adanced my ignition timing by about 2-3 degrees...could that be why it is still off ?</TD></TR></TABLE>I guess what I really meant was, did you check your spark timing AFTER changing the timing belt? If your intake cam was 1/2-tooth advanced but now it's 1/2-tooth retarded, then your spark timing isn't the same place where you think it is...

Cam timing & spark timing can both make it run bad, but maybe spark timing has the stronger influence? I would double-check both.

 

If everything lined up before changing the belt, and you line up everything afterwards, there shouldn't be any need to adjust ignition timing.

How is the belt tension? Did you tension the belt properly after installing it? If the belt doesn't have the proper tension on it, it might cause the cams to not be in exactly the right position in relation to the crankshaft.

 

Did you put the exh cam 1 tooth back, Then tension the slack out?

That works for me everytime.

 

Even though I know how to do a timing belt and everything and could probably get it all lined up, I think I'm still going to make marks on the belt and all the sprockets before I pull my old one off, so nothing like this happens.

 

well that s the thing......I think i read somewhere that the belt tension is suppose to be such that there is a one inch deflection along the front side.....well on mine there is about a half an inch deflection....in otherwards, its pretty damn tight...could that be the problem ?

Should I try to turn the exhaust cam counter clockwise one tooth, and then retension the belt ?

 

Did you know that there are holes in the tops of the camshafts that allow you to keep them aligned at TDC while you put the belt on? You can put drill bits in the holes to keep them in place (don't forget to take them out before you start turning the crank to tension the belt!!)

There are also hex shaped castings on the cams so you can make fine adjustments with a wrench (a big crescent wrench worked for me but I think its 27 mm if you have that).

Makes it easier to keep things in place while you put the new belt on. Then you go through the retensioning procedure and things should be good.

 

well I noticed that there are 4 holes on the top......when it looks like the moto is at TDC, bits can go inot the right top hole and bottom left hole but not the other two

 

Perhaps your's is a little different being a GS-R. I have a '94LS (B18B1) and it just has the two holes in the cams that align with the holes in the engine block at TDC. They are only on the drivers side of the camshafts on the LS.

 

oh ok..the gs-r has 2 on the drivers side, and 2 on the passenger side.


does anyone have any other ideas......could it possibly be that the timing belt is on too tight ?

 

I don't know, but if you're in doubt, just re-tension it:

Loosen tensioner bolt, then re-tighten.

Rotate engine over by about 5-6 revolutions.

Loosen the tensioner bolt by 1/2 turn.

Rotate the engine by 3 teeth on the cam gear.

Tighten the tensioner bolt and torque to spec.

Then set the #1 piston to TDC and check to make sure the cam gears are lined up as they should be.

 

just re time it, use 2 5mm punches and take off cam cover time it perfectly then check and change with a timing light