This is related to my current emissions problem as per my "minumum idle speed" thread. It's also related to my thread earlier this year (started late last year) entitled "1994 Chevy Surburban running way too rich and ..."
Namely, in that prior thread I talked about the problem I was having setting the timing. If you're really bored, you can read it here -
http://chevyforum.org/chevy-forums/showpost.php?p=47524&postcount=31
So since I'm now running a tad too rich at idle to pass NJ inspection, and since a few people have suggested retarding the timing a bit, I went back to that "sawtooth timing plate" (which is apparently called the "timing tab") today. As I said in my prior thread, the plate is hard to see and hard to get at. I never did go back (last time) and try to clean it up so that I could actually read where the "0" mark is. So I decided to do that today.
I removed the upper plastic fan shroud to give me better access. Then I loosened the serpentine belt and moved it out of the way. That gave me very good access to the timing plate for both viewing and cleaning. I hit it with a wire brush and got it cleaned up a bit.
But the bad news is that it's pretty rusty and I still can't make out much of anything on it other than MAYBE a "4" on one of the marks. I'm pretty sure it's a 4, but not positive.
Now, here's a timing plate that looks very much like mine -
http://ww2.justanswer.com/uploads/ZZdaryl/2010-01-30_181920_timing2.png
that came from this article -
http://www.justanswer.com/gm/32woa-1994-gmc-sanoma-4x4-4-3-lt-engine-ned.html
As you can see, it's suggested in that article that this timing plate is not for my 5.7 L Suburban engine. But it's the closest one to mine that I've found so far. It even appears to have the "see thru" tube that mine has (I think it's that circular thing at the bottom of the plate in the picture). One difference, however, is that my plate only has 3 "teeth" whereas this one has 4. So mine doesn't have the last tooth which is the last tooth at the top in the picture.
But my plate does have the deeper cut which is the "0" mark on this plate. Therefore, I suspect that this deeper cut on my plate is also the "0" mark. Consistent with this notion is the fact that the "4" that I think I can make out on my plate is also where the 4 on this plate is.
Also consistent with this notion is what else I did; namely, I positioned the crank pulley such that the timing mark lined up with the deeper cut "0" mark on my plate (which I'm assuming is the "0" mark). I then removed the distributor cap and checked the rotor position vis-a-vis the #1 lug on the cap. The rotor was significantly to the left of that #1 lug, which would indicate that the timing is somewhat advanced. That makes sense because when I set the timing back when, I used the yellow mark that was already on the timing plate (put there by a prior mechanic).
So if I'm reading my plate correctly, that prior yellow mark was about 8 degrees before TDC, and thus I set the timing pretty significantly advanced.
So, my question very simply is this:
If anyone out there knows what the timing plate looks like on a 1994 K1500 5.7 L TBI Chevy Suburban, and can thus confirm (or disconfirm?) that the "0" mark is where I think it is, I'd sure appreciate it.
Tomorrow I'll go to my local library and see if Chiltons shows it for my truck. But I'm not too hopeful that it will.
P.S.: The "see thru" tube is not used on my truck to set the timing. I'm guessing that it's used on other models and Chevy just put the same plate on many different models.
Namely, in that prior thread I talked about the problem I was having setting the timing. If you're really bored, you can read it here -
http://chevyforum.org/chevy-forums/showpost.php?p=47524&postcount=31
So since I'm now running a tad too rich at idle to pass NJ inspection, and since a few people have suggested retarding the timing a bit, I went back to that "sawtooth timing plate" (which is apparently called the "timing tab") today. As I said in my prior thread, the plate is hard to see and hard to get at. I never did go back (last time) and try to clean it up so that I could actually read where the "0" mark is. So I decided to do that today.
I removed the upper plastic fan shroud to give me better access. Then I loosened the serpentine belt and moved it out of the way. That gave me very good access to the timing plate for both viewing and cleaning. I hit it with a wire brush and got it cleaned up a bit.
But the bad news is that it's pretty rusty and I still can't make out much of anything on it other than MAYBE a "4" on one of the marks. I'm pretty sure it's a 4, but not positive.
Now, here's a timing plate that looks very much like mine -
http://ww2.justanswer.com/uploads/ZZdaryl/2010-01-30_181920_timing2.png
that came from this article -
http://www.justanswer.com/gm/32woa-1994-gmc-sanoma-4x4-4-3-lt-engine-ned.html
As you can see, it's suggested in that article that this timing plate is not for my 5.7 L Suburban engine. But it's the closest one to mine that I've found so far. It even appears to have the "see thru" tube that mine has (I think it's that circular thing at the bottom of the plate in the picture). One difference, however, is that my plate only has 3 "teeth" whereas this one has 4. So mine doesn't have the last tooth which is the last tooth at the top in the picture.
But my plate does have the deeper cut which is the "0" mark on this plate. Therefore, I suspect that this deeper cut on my plate is also the "0" mark. Consistent with this notion is the fact that the "4" that I think I can make out on my plate is also where the 4 on this plate is.
Also consistent with this notion is what else I did; namely, I positioned the crank pulley such that the timing mark lined up with the deeper cut "0" mark on my plate (which I'm assuming is the "0" mark). I then removed the distributor cap and checked the rotor position vis-a-vis the #1 lug on the cap. The rotor was significantly to the left of that #1 lug, which would indicate that the timing is somewhat advanced. That makes sense because when I set the timing back when, I used the yellow mark that was already on the timing plate (put there by a prior mechanic).
So if I'm reading my plate correctly, that prior yellow mark was about 8 degrees before TDC, and thus I set the timing pretty significantly advanced.
So, my question very simply is this:
If anyone out there knows what the timing plate looks like on a 1994 K1500 5.7 L TBI Chevy Suburban, and can thus confirm (or disconfirm?) that the "0" mark is where I think it is, I'd sure appreciate it.
Tomorrow I'll go to my local library and see if Chiltons shows it for my truck. But I'm not too hopeful that it will.
P.S.: The "see thru" tube is not used on my truck to set the timing. I'm guessing that it's used on other models and Chevy just put the same plate on many different models.
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