Is This Timing Belt 1 Tooth Off?? 87 S-4
09-21-2008, 11:37 PM
#46
Rennlist Member
If the belt job has been done, then that side timing will be near 15 degrees off! (crank degrees) that a lot!! when my car jumped 2-3 teeth in a race qual session, the car BARELY ran! . anyway, I guess as long as the shop, (or whoever) didnt change the precision timing to match the new pulley position, just putting the pulley back to the V marks is a quick solution. if they didnt, and actually timed the engine (unlikely), then its better to just put it back the way you found it, after checking it with the porken tool.
mk
mk
09-21-2008, 11:43 PM
#47
Rennlist Member
The easier way, is to just string the belt up around the driver side and match the marks up. keep a wrench on the cam bolt and put pressure on it CCW, tighting up the belt around the oil pump and crank. Then, you just line up the other side and slip the belt over the pulley.
done.
mk
done.
mk
09-22-2008, 01:52 AM
#48
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Tom M. and i just checked mine today. took a couple hours since the engine was hot, but we found the rear pulley notches were dead on, and Ken's tool showed driver side = 0º, pass side = +1.5º advanced (engine hot). we didn't think this was so far off that it was worth messing with. i'd rather see it when cold before deciding on any adjustments...
09-22-2008, 09:35 AM
#49
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To make the passenger side cam gear 1/2 tooth advanced like you suggest, do you turn it slightly clockwise or counterclockwise?
Brent, You turn it slightly clockwise since it is not really very tight until you put the tensioner on and tighten the belt.
Brent, You turn it slightly clockwise since it is not really very tight until you put the tensioner on and tighten the belt.
09-22-2008, 12:47 PM
#50
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Ken,
Do you have an answer for me on this? You make a statement originally that is kind of confusing. can you clarify?
thanks,
Mk
Do you have an answer for me on this? You make a statement originally that is kind of confusing. can you clarify?
thanks,
Mk
BUMP.
So my real question regarding "variances" was:
How does the WSM set the all the 32valve cams to 2 degrees advanced of the cam key centers? or are you only talking about the WSM setting for the passenger cam only?
I thought the WSM would set the cam timing to be 0, or right on the cam key center, unless its the passenger cam that you state should be 1-2 degrees retarded.
ALSO, a question ive never had answered to ths point, is why the WSM has the different cams with a different spread between the cams as far as degree offset. 1.6 or 1.8 to 2mm intake lifter depression (ie S4 vs 85 cams)
mk
Quote:
Originally Posted by PorKen
The 32V'r is indexed of the center of the cam key. (This is the zero on the V1.) The WSM method sets the cam timing to 2° (crank) advanced of the cam key center for all 32V cams. This is the zero on the V2. The difference in the WSM measurements between sides equals 2° retard for the 1/4 bank to compensate for engine expansion advance.
It's much easier to get the correct timing with the 32V'r versus using a dial indicator.
So my real question regarding "variances" was:
How does the WSM set the all the 32valve cams to 2 degrees advanced of the cam key centers? or are you only talking about the WSM setting for the passenger cam only?
I thought the WSM would set the cam timing to be 0, or right on the cam key center, unless its the passenger cam that you state should be 1-2 degrees retarded.
ALSO, a question ive never had answered to ths point, is why the WSM has the different cams with a different spread between the cams as far as degree offset. 1.6 or 1.8 to 2mm intake lifter depression (ie S4 vs 85 cams)
mk
Quote:
Originally Posted by PorKen
The 32V'r is indexed of the center of the cam key. (This is the zero on the V1.) The WSM method sets the cam timing to 2° (crank) advanced of the cam key center for all 32V cams. This is the zero on the V2. The difference in the WSM measurements between sides equals 2° retard for the 1/4 bank to compensate for engine expansion advance.
It's much easier to get the correct timing with the 32V'r versus using a dial indicator.
09-22-2008, 01:54 PM
#51
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The help desk is by subscription, only.
When measured in degrees at TDC #1, all the exhaust cams are ground 2° advanced of the center of the cam key. The same machine was likely used to grind each type of cam, so they all start at the same reference point.
2° from the center of the cam key is not related to the actual cam timing, it is just a reference measurement. Refer to the WSM cam tables for the timing for each type of cam.
Depending on how the cams are ground, the lobe will be fatter or thinner when measured at 20°. Even though the GT and S3 cams have the same lift and duration, the GT intake cam is advanced 8°, so the lobe is fatter at 20° when compared to the S3 at 20°.
The bank to bank specification is different between grinds because each type of cam will push a little more or less for a 2° movement, when measured at 20°.
EOF
When measured in degrees at TDC #1, all the exhaust cams are ground 2° advanced of the center of the cam key. The same machine was likely used to grind each type of cam, so they all start at the same reference point.
2° from the center of the cam key is not related to the actual cam timing, it is just a reference measurement. Refer to the WSM cam tables for the timing for each type of cam.
Depending on how the cams are ground, the lobe will be fatter or thinner when measured at 20°. Even though the GT and S3 cams have the same lift and duration, the GT intake cam is advanced 8°, so the lobe is fatter at 20° when compared to the S3 at 20°.
The bank to bank specification is different between grinds because each type of cam will push a little more or less for a 2° movement, when measured at 20°.
EOF
09-23-2008, 02:20 AM
#52
Rennlist Member
Thanks for renewing my subsciption! 
ok, so you have compensated for a manufacturing abnormality, but what about the bank to bank differences. They are just a little off as well, and the cam setting spec takes care of this.
Thanks, I think i understand now.
by the way, what do you suspect the retarding of my cam settings will do. remember, i do have the 85 cams and maybe they needed to be advanced to work properly. Maybe retarding them to match the 0 spec from where i had them (same settings as near the GT cam), is going too far and reduce HP more than the adjustments on the S4 or GT cams.
But then again, maybe the change wont be that significant. It will be interesting to see if there was a torque loss and a hp gain like Louie saw on his cam adjustments. (3 degree advance vs 3 degree retard)
Thanks for the clarification. The tool is a great idea and I will probably get one next time i dig into the timing again!
Mk
ok, so you have compensated for a manufacturing abnormality, but what about the bank to bank differences. They are just a little off as well, and the cam setting spec takes care of this.
Thanks, I think i understand now.
by the way, what do you suspect the retarding of my cam settings will do. remember, i do have the 85 cams and maybe they needed to be advanced to work properly. Maybe retarding them to match the 0 spec from where i had them (same settings as near the GT cam), is going too far and reduce HP more than the adjustments on the S4 or GT cams.
But then again, maybe the change wont be that significant. It will be interesting to see if there was a torque loss and a hp gain like Louie saw on his cam adjustments. (3 degree advance vs 3 degree retard)
Thanks for the clarification. The tool is a great idea and I will probably get one next time i dig into the timing again!
Mk
The help desk is by subscription, only.
When measured in degrees at TDC #1, all the exhaust cams are ground 2° advanced of the center of the cam key. The same machine was likely used to grind each type of cam, so they all start at the same reference point.
2° from the center of the cam key is not related to the actual cam timing, it is just a reference measurement. Refer to the WSM cam tables for the timing for each type of cam.
Depending on how the cams are ground, the lobe will be fatter or thinner when measured at 20°. Even though the GT and S3 cams have the same lift and duration, the GT intake cam is advanced 8°, so the lobe is fatter at 20° when compared to the S3 at 20°.
The bank to bank specification is different between grinds because each type of cam will push a little more or less for a 2° movement, when measured at 20°.
EOF
When measured in degrees at TDC #1, all the exhaust cams are ground 2° advanced of the center of the cam key. The same machine was likely used to grind each type of cam, so they all start at the same reference point.
2° from the center of the cam key is not related to the actual cam timing, it is just a reference measurement. Refer to the WSM cam tables for the timing for each type of cam.
Depending on how the cams are ground, the lobe will be fatter or thinner when measured at 20°. Even though the GT and S3 cams have the same lift and duration, the GT intake cam is advanced 8°, so the lobe is fatter at 20° when compared to the S3 at 20°.
The bank to bank specification is different between grinds because each type of cam will push a little more or less for a 2° movement, when measured at 20°.
EOF
09-23-2008, 12:49 PM
#53
Inventor
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I regained 15+ rwhp going from +3° to 0° on my S3, same dyno session.
In general, each degree ± moves the peaks about 100 rpm.
In general, each degree ± moves the peaks about 100 rpm.
09-23-2008, 01:07 PM
#54
Rennlist Member
Interesting. shows that this adjustment might have bought me something.
do you have a dyno print out of this? Louie's dyno runs only showed a 3-5hp gain and a slight shift to the right for the HP curve.
mk
do you have a dyno print out of this? Louie's dyno runs only showed a 3-5hp gain and a slight shift to the right for the HP curve.
mk
09-23-2008, 01:12 PM
#55
Rennlist Member
Regarding the bank to bank spec differences (actually, adjustment specs)
are you saying there is a difference between the driver and passneger intake cam lobe where one side is purposly retarded because it has a slightly different profile? I know part of the adjustment spec is for the engine expansion, and part might be due to something else. However, i still dont get why there would be such a differnece betwen S4 and S3 cams. 2mm lifter depression for both driver sides and then either 1.6 or 1.8mm for the passenger sides. (85 vs S4)
mk
are you saying there is a difference between the driver and passneger intake cam lobe where one side is purposly retarded because it has a slightly different profile? I know part of the adjustment spec is for the engine expansion, and part might be due to something else. However, i still dont get why there would be such a differnece betwen S4 and S3 cams. 2mm lifter depression for both driver sides and then either 1.6 or 1.8mm for the passenger sides. (85 vs S4)
mk
09-23-2008, 01:28 PM
#56
Inventor
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Yes.
No. 
Different lobe ramps, valve opening times.
EOF
Different lobe ramps, valve opening times.
EOF
09-23-2008, 01:42 PM
#57
Rennlist Member
09-23-2008, 01:46 PM
#58
Inventor
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Side to side, no. S4 versus S3, yes.
No.
EOF
No.
EOF
09-23-2008, 01:54 PM
#59
Rennlist Member
But, isnt the reason for the lag spec anyway due to block expansion? If so did the 85 engine grow more and require a greater retarding of the driver cam?
OR, is it because that "growth" creates a different disparity in the 85 cam vs the S4 cam? That must be it. I think I get it.
However, the GT cams have the same profile and those spec's are only spaced apart by .3mm. (2.8mm/3.1mm) I guess its all shaving hairs, but i was curious.
mk
OR, is it because that "growth" creates a different disparity in the 85 cam vs the S4 cam? That must be it. I think I get it.
However, the GT cams have the same profile and those spec's are only spaced apart by .3mm. (2.8mm/3.1mm) I guess its all shaving hairs, but i was curious.
mk
09-23-2008, 02:03 PM
#60
Inventor
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Yes. No.
No. No.
There is not the same lift at 22° as there is at 20°. The S4 has different lift at 22° than the S3 has at 22°.
The GT intake cam is ground 8° advanced of the S3 - the GT has different lift at 22° than the S3 has at 22°.
EOF
No. No.
There is not the same lift at 22° as there is at 20°. The S4 has different lift at 22° than the S3 has at 22°.
The GT intake cam is ground 8° advanced of the S3 - the GT has different lift at 22° than the S3 has at 22°.
EOF