Timing shortcuts

[georgeb]

After a rash of suspected jumped timing cases I decided to check up on my own responses by checking the cam timing on my cars. Turns out that my suggestions (from the manual) aren't worth a pint of pee when tried on an actual car.
With the top cover removed it's easy to line up the 12 and 3 marks. None of my three cars have the top cover installed. I did chop the part that wraps around the idler wheel on one cover for ease of removal but haven't employed it yet.
The problem is lining up the crank. There's a notch in the flange behind the sprocket but I cannot see it on my EFI car because of the VAF. There's also a notch on the pulley that lines up with the T on the scale. The notch is tiny and is hidden by the scale because of the sight angle. There is a keyway that can be felt but hard to know if it's at 12 o'clock.
What I did was remove the pulley, file the notch bigger and paint it with Wite-out. Because I still cannot see it I also made a white mark on the pulley OPPOSITE the keyway so it points directly down. Even though there's nothing to line it up with, due to the 2:1 ratio and the crank pulley being larger than the cam gear, it would be noticably off if it slipped a tooth.
There are two marks on the scale on an EFI car: The T mark (cam) and 10 degrees (ign). I seriously don't know how a timing light could see that thing. I might weld a tab to the notch next time.

[Christ]

I can't get a timing light in on the right angle to actually see the timing mark on the crank without pulling the grille. I played with it for like half an hour once, finally got it ONE time, and ended up giving up on it and doing it by ear like I always have (on a friend's Festiva). Later, he had the grille out and decided to check it again, and it was as close as anyone could hope for. I guess that happens when you've been doing it for like 10 years.

I haven't done anything with Cam timing on the Festiva *and don't plan on it, at least w/ the B3*, but on my Civic, it was always set perfectly using a *gasp* screwdriver in the spark plug hole for the crank position. One time, I used a hole saw and cut a notch in the bell housing of the trans on my Civic, and marked the tooth that was up at TDC on the flywheel, so I didn't have to mess w/ the pulley end at all. Stick a screwdriver in the bell housing to turn the flywheel until the mark points up, check the marks on the cam against the gasket surface (they were at 9 and 3 on that particular engine) of the cylinder head.

[blkfordsedan]

You're getting ignition timing and cam timing confused. The (T) and the (10) are for ignition timing and have absolutely nothing to do with cam timing.
Cam timing is not adjustable. If its off by even 1 tooth you'll know something is wrong. That is very rare for a timing belt to slip a tooth. I've never seen it happen in my life. Every engine has some kind of mark on all cam sprockets or gears to allow them to be lined up...its either on or off, no in-between, and it doesn't change as the motor gets older. Hope that helps.

[georgeb]

The "screwdriver in the spark plug hole" and some threads pointing to possible cam timing issues are the reasons I did this research. I am attempting to pinpoint TDC without any dissassembly. If someone has purchased a car that the PO has worked on and it won't run right the first thing you would want to check is the cam timing. Without a definitive mark that can be seen this is difficult. Also, the 0 mark on the scale is not for ignition unless it is a carbed model. When the sprocket notch is lined up with the mark, the pulley notch will be lined up with the 0 on the scale. I checked it.

[blkfordsedan]

OK, I see what you're trying to do now, LOL. I agree, if a PO has installed a t-belt it could be off a tooth. IIRC, even being off 1 tooth would be like 15 or 16 degrees, so it would be very appearant that somethings wrong. If all you want to do is a quick check, then that should be simple enough. Yes, in theory, one of the marks on the crank pulley should line up with a mark on the ignition timing scale to indicate TDC. I've never looked at mine, so I can't say how hard it is to see or what lines up, but I've never seen a motor that didn't have something to indicate TDC. If you say the "0" lines up, then that would make sense. The cam sprocket is twice as big as the crank sprocket and therefore turns half as fast (i.e. it takes 2 turns of the crank to get 1 turn on the cam). So......every other time the crank pulley ignition timing mark lines up at TDC, the cam marks should line up at 12:00 and 3:00....and therefore every time the cam sprocket marks are at 12:00 & 3:00, the crank should line up at TDC. No reason to use any kind of screwdriver to feel the piston or anything like that.

[htchbck]

The two I've picked up that weren't running due to a botched Tb install were waaay out. One was a full 180 off, the other 90 degrees (they had lined the 3oclock mark straight up).

[georgeb]

OK, I see what you're trying to do now, LOL. I agree, if a PO has installed a t-belt it could be off a tooth. IIRC, even being off 1 tooth would be like 15 or 16 degrees, so it would be very appearant that somethings wrong. If all you want to do is a quick check, then that should be simple enough. Yes, in theory, one of the marks on the crank pulley should line up with a mark on the ignition timing scale to indicate TDC. I've never looked at mine, so I can't say how hard it is to see or what lines up, but I've never seen a motor that didn't have something to indicate TDC. If you say the "0" lines up, then that would make sense. The cam sprocket is twice as big as the crank sprocket and therefore turns half as fast (i.e. it takes 2 turns of the crank to get 1 turn on the cam). So......every other time the crank pulley ignition timing mark lines up at TDC, the cam marks should line up at 12:00 and 3:00....and therefore every time the cam sprocket marks are at 12:00 & 3:00, the crank should line up at TDC. No reason to use any kind of screwdriver to feel the piston or anything like that.

Exactly. A"quick check" is what I'm looking for. Also, there is no "0" on the EFI scale. It says "T" in case anyone is looking for a 0. A day too late I also discovered that a V could be filed at the T and 10 marks on the plastic scale that would expose the pulley white mark. You can't read the scale otherwise.

[blkfordsedan]

I guess the "T" is for TDC and "10" is 10* BTDC? I've never actually used a timing light to set the ignition timing on my B3 or paid any attention to the timing marks. I just set it by ear and feel. I seem to remember trying it once and something was odd....like a scale molded into the belt cover in two different places or something?
When I get my B6 rebuild completed, I'll need to pay close attention while the engine is out. I would really like to use an actual timing light so I can get it set properly without too much drama.

[blkfordsedan]

The two I've picked up that weren't running due to a botched Tb install were waaay out. One was a full 180 off, the other 90 degrees (they had lined the 3oclock mark straight up).

How can they possibly get it that far off, LOL? All I can think of is they must not have even tried. I did a 2.2L Chrysler once and got it off by 1 tooth (retarded). IIRC, it was very vague in terms of being able to line any marks up. Luckily I fired it up before putting anything back together. It fired up and it actually ran pretty well, but the throttle response was a little sluggish . I could see where someone with less experience may not have noticed and just put it back together.

[htchbck]

Well I can see how the 90* happened, since there ARE two marks on the cam and they just got the wrong mark lined up.