PTV checking with VVT cam
10-22-2012, 10:22 PM
#61
ModSquad
iTrader: (6)
I would like to thank you guys for all the valuable information in this thread. I got my shortblock assembled yesterday, with my mast VVT camshaft, and I will be checking PTV tomorrow, as I cleaned an assembled my heads today. How do you request that this thread be made a sticky?
10-23-2012, 06:06 PM
#62
Some copy-paste from my build thread since this is relevant here:
I took apart my phaser completely, down to the individual loose components. To some degree I just couldn't help myself - I wanted to see how it worked. There are some very nicely made parts in there with very tight fits. I don't know how GM can sell replacements for around $100 list. Each phaser vane has a small leaf spring that keeps it biased outward (careful - these are easy to lose). The hub in the center that attaches to the cam is a very tight rotating fit with the housing. There are tiny feed holes all over the place for oil. And there's a small spring loaded plunger behind the hub that seems to either regulate oil flow or maybe act as a detent - I'm not sure. The trigger wheel that also retains the "clock" spring is held by 3 extremely small press pins. If you take it apart this far be very careful not to lose parts and also to get each part back together in the correct orientation/clocking so you don't inadvertently affect the came phasing. I took photos as I took it apart and tracked parts on the workbench to make sure they got right back to where they started.
One of the questions I wanted to answer was can this thing be put back together? My conclusion is, maybe. The coil spring is extremely stiff so it would be very hard to rewind. There appear to be some access holes on the trigger wheel where you could put pins to temporarily hold the spring together while assembling it onto the rest of the phaser. I think once you get the spring wound, the rest of the assembly can be done and would be reasonably straight forward, but winding that spring will be extremely difficult. I plan to give this a try once I'm done with this phaser, but I plan to buy a new one regardless for actual use.
Okay, so on to the progress. After disassembling the phaser, I added the phaser limiter block from Comp Cams. I found that the screws holding the phaser together were actually the perfect diameter to block the vanes into the fully advanced position, so I cut a screw and put it in. This would seem like a waste of a screw, but I had other troubles that led me there. On an initial assembly, one of the torx drives completely stripped out of one of the phaser bolts. Maybe I applied too much torque or maybe the tool didn't fit well, but the result was drilling out the head of the screw so I could get it out. What a pain that was. I will be VERY careful torquing these next time.
With the phaser locked in the fully advanced position, I installed the cam and got started degreeing it using the no1 cylinder and measuring from my solid lifters. I found TDC using the indicator method, looking for the spots on either side of TDC where the piston was .100 below peak. I measured each side of TDC with the piston coming up from the bottom of the bore after pressing down on the piston by hand to take out slack in the bearing/pin clearances (had to rotate CW for one and CCW for the other to make this happen). I checked it 3 times to make sure it was right; each time .100 corresponded to equal distance on either side of TDC on the degree wheel. For the cam timing, I measured through three revolutions for both intake & exhaust and got the same values each time. I will outline the steps once I upload photos, but let me just discuss the results for now:
I'm not 100% sure what the acceptance limits should be for a cam. My gut says these numbers are fine, but what do you think?
The next step is to check piston-valve clearance. I got everything setup last night, but had to stop work to get to bed (will outline with photos later).
I took apart my phaser completely, down to the individual loose components. To some degree I just couldn't help myself - I wanted to see how it worked. There are some very nicely made parts in there with very tight fits. I don't know how GM can sell replacements for around $100 list. Each phaser vane has a small leaf spring that keeps it biased outward (careful - these are easy to lose). The hub in the center that attaches to the cam is a very tight rotating fit with the housing. There are tiny feed holes all over the place for oil. And there's a small spring loaded plunger behind the hub that seems to either regulate oil flow or maybe act as a detent - I'm not sure. The trigger wheel that also retains the "clock" spring is held by 3 extremely small press pins. If you take it apart this far be very careful not to lose parts and also to get each part back together in the correct orientation/clocking so you don't inadvertently affect the came phasing. I took photos as I took it apart and tracked parts on the workbench to make sure they got right back to where they started.
One of the questions I wanted to answer was can this thing be put back together? My conclusion is, maybe. The coil spring is extremely stiff so it would be very hard to rewind. There appear to be some access holes on the trigger wheel where you could put pins to temporarily hold the spring together while assembling it onto the rest of the phaser. I think once you get the spring wound, the rest of the assembly can be done and would be reasonably straight forward, but winding that spring will be extremely difficult. I plan to give this a try once I'm done with this phaser, but I plan to buy a new one regardless for actual use.
Okay, so on to the progress. After disassembling the phaser, I added the phaser limiter block from Comp Cams. I found that the screws holding the phaser together were actually the perfect diameter to block the vanes into the fully advanced position, so I cut a screw and put it in. This would seem like a waste of a screw, but I had other troubles that led me there. On an initial assembly, one of the torx drives completely stripped out of one of the phaser bolts. Maybe I applied too much torque or maybe the tool didn't fit well, but the result was drilling out the head of the screw so I could get it out. What a pain that was. I will be VERY careful torquing these next time.
With the phaser locked in the fully advanced position, I installed the cam and got started degreeing it using the no1 cylinder and measuring from my solid lifters. I found TDC using the indicator method, looking for the spots on either side of TDC where the piston was .100 below peak. I measured each side of TDC with the piston coming up from the bottom of the bore after pressing down on the piston by hand to take out slack in the bearing/pin clearances (had to rotate CW for one and CCW for the other to make this happen). I checked it 3 times to make sure it was right; each time .100 corresponded to equal distance on either side of TDC on the degree wheel. For the cam timing, I measured through three revolutions for both intake & exhaust and got the same values each time. I will outline the steps once I upload photos, but let me just discuss the results for now:
Cam Card / Measured
Intake @ 0.050
Open (BTDC): 5 / 7
Close (ABDC): 41 / 40.5
ICL (ATDC): 108 / 106.75*
Duration: 227 / 227.5*
Lift: .361 / .362
Exhaust @ 0.050
Open (BBDC): 55 / 57
Close (BTDC): 0 / 1
ECL (BTDC): 117.5* / 119*
Duration: 235 / 236*
Lift: .365 / .365
LSA: 113 (112.75*) / 112.875*
* calculated from open/close events using this calculator
Compared to the cam card, the cam appears to be advanced ~1.25deg (easily adjusted w/ VVT). The intake has 0.5deg more duration & 0.001in more tappet lift. The exhaust has 1deg more duration. The LSA seems to split the difference between what's stated on the cam card and what I calculated from the cam card open/close events.Intake @ 0.050
Open (BTDC): 5 / 7
Close (ABDC): 41 / 40.5
ICL (ATDC): 108 / 106.75*
Duration: 227 / 227.5*
Lift: .361 / .362
Exhaust @ 0.050
Open (BBDC): 55 / 57
Close (BTDC): 0 / 1
ECL (BTDC): 117.5* / 119*
Duration: 235 / 236*
Lift: .365 / .365
LSA: 113 (112.75*) / 112.875*
* calculated from open/close events using this calculator
I'm not 100% sure what the acceptance limits should be for a cam. My gut says these numbers are fine, but what do you think?
The next step is to check piston-valve clearance. I got everything setup last night, but had to stop work to get to bed (will outline with photos later).
10-23-2012, 06:07 PM
#63
As promised, here are some photos of my progress. First, here is the disassembled phaser with both the Comp Cams limiter and a cut-down screw (very hard to see sorry) between the vanes to lock it into a fully advanced position. You are looking at the rear of the assembly in this photo, so rotating the vanes CCW here will rotate the cam CW (advanced) with respect to the engine. Note you can also see in the top right of this photo the unsprung "clock" spring that keeps this assembly in the advanced position when no oil pressure is applied.
I lubed the cam with assembly lube and carefully installed it in the block while holding it with the long bolt supplied with the cam. Then I installed the timing set "dot-to-dot", using the long bolt to pull the cam forward while seating the phaser onto the cam pin. Note in these photos I have an allen wrench installed to keep the tensioner held back, but later removed it during the degreeing process.
Next I installed the degree wheel I bought from Summit. I fashioned a pointer from a coat hanger and mounted it on the front of the block, cutting the end to a point for improved accuracy. Then I used a magnetic base indicator stand to position my indicator over the center of the piston. I used the method described in my previous post to find TDC and adjusted the pointer appropriately.
After cleaning and oiling the outside of my welded-solid lifters, I installed them in their bores over the cam lobe and made sure they moved freely. Next came the most challenging aspect of this - getting this stand adjusted so I could actually measure. It sounds silly, but it did take a bit of time just finding a good way to position the arms to make this work. I also had to install an extended tip on my indicator to make it reach. Fortunately I have a set of tips in my machinist box. I have to admit this stand and indicator came from Harbor Freight many years ago when I only intended to use them once for setting up gears. I have some better quality indicators in my box, but none with enough travel for this job.
Here you can see I used the edge of the lifter to read from. Even though the plunger was welded on these lifters, I felt the flat surface on the outside would be a better location to read from.
The results of degreeing the cam are described in my previous post. Altogether it took about two hours and probably less than $50 in tools between the Summit wheel, coat hanger and HF indicator & stand. When i get further along I will be repeating some of these measurements with the phaser locked to full retard so I can see how much mechanical phaser travel is available.
Next I moved on to piston-valve clearance. The first step was cleaning and installing the old MLS head gaskets. The new gaskets I bought are the same GM part number, so these old gaskets should replicate the compressed thickness.
Installing the head took some time because I am using ARP fasteners and needed to lube them with the ARP thread lube. This is important because it gives more consistent clamping. I put a dab under the head of the bolt, a dab under the washer, and a smearing over the first ten threads or more which tends to be enough to coat them completely while they're installed. I torqued the bolts using the factory-recommended sequence in 3 steps per the ARP instructions. Then I came up with yet another creative way to position my indicator stand to measure valve-piston clearance.
Before installing the rockers, I dropped in an adjustable pushrod so I can acheive zero lash. My plan is to rotate the crank in small increments (using the degree wheel for reference), push the valve down with my finger until it contacts the piston, and measure the valve travel with the indicator positioned as above. This will tell me the valve clearance for that position of the crank. I will have to repeat until I find the minimum clearance. I will do this for both the intake and exhaust, although the intake should be most limited in this scenario with the phaser fully advanced since the intake will be opening sooner as the piston is approaching TDC. When the phaser is fully retarded, the exhaust valve will have it's minimum clearance since it will be closing later as the piston approaches TDC.
I lubed the cam with assembly lube and carefully installed it in the block while holding it with the long bolt supplied with the cam. Then I installed the timing set "dot-to-dot", using the long bolt to pull the cam forward while seating the phaser onto the cam pin. Note in these photos I have an allen wrench installed to keep the tensioner held back, but later removed it during the degreeing process.
Next I installed the degree wheel I bought from Summit. I fashioned a pointer from a coat hanger and mounted it on the front of the block, cutting the end to a point for improved accuracy. Then I used a magnetic base indicator stand to position my indicator over the center of the piston. I used the method described in my previous post to find TDC and adjusted the pointer appropriately.
After cleaning and oiling the outside of my welded-solid lifters, I installed them in their bores over the cam lobe and made sure they moved freely. Next came the most challenging aspect of this - getting this stand adjusted so I could actually measure. It sounds silly, but it did take a bit of time just finding a good way to position the arms to make this work. I also had to install an extended tip on my indicator to make it reach. Fortunately I have a set of tips in my machinist box. I have to admit this stand and indicator came from Harbor Freight many years ago when I only intended to use them once for setting up gears. I have some better quality indicators in my box, but none with enough travel for this job.
Here you can see I used the edge of the lifter to read from. Even though the plunger was welded on these lifters, I felt the flat surface on the outside would be a better location to read from.
The results of degreeing the cam are described in my previous post. Altogether it took about two hours and probably less than $50 in tools between the Summit wheel, coat hanger and HF indicator & stand. When i get further along I will be repeating some of these measurements with the phaser locked to full retard so I can see how much mechanical phaser travel is available.
Next I moved on to piston-valve clearance. The first step was cleaning and installing the old MLS head gaskets. The new gaskets I bought are the same GM part number, so these old gaskets should replicate the compressed thickness.
Installing the head took some time because I am using ARP fasteners and needed to lube them with the ARP thread lube. This is important because it gives more consistent clamping. I put a dab under the head of the bolt, a dab under the washer, and a smearing over the first ten threads or more which tends to be enough to coat them completely while they're installed. I torqued the bolts using the factory-recommended sequence in 3 steps per the ARP instructions. Then I came up with yet another creative way to position my indicator stand to measure valve-piston clearance.
Before installing the rockers, I dropped in an adjustable pushrod so I can acheive zero lash. My plan is to rotate the crank in small increments (using the degree wheel for reference), push the valve down with my finger until it contacts the piston, and measure the valve travel with the indicator positioned as above. This will tell me the valve clearance for that position of the crank. I will have to repeat until I find the minimum clearance. I will do this for both the intake and exhaust, although the intake should be most limited in this scenario with the phaser fully advanced since the intake will be opening sooner as the piston is approaching TDC. When the phaser is fully retarded, the exhaust valve will have it's minimum clearance since it will be closing later as the piston approaches TDC.
10-24-2012, 11:06 AM
#64
Had just enough time last night to measure the intake valve clearance with the phaser at full advance. I did this by rotating the crank in 2 degree increments, pushing down on the tip of the valve (through the rocker) and measuring the travel of the valve until it hit the piston. I got a minimum intake valve to piston clearace of .210in. Here is the raw data:
crank deg (starting from BTDC) / clearance (in)
4 .270
2 .260
0 .250
2 .235
4 .227
6 .219
8 .210
10 .210
12 .210
14 .210
16 .222
18 .231
20 .245
22 .258
I thought it was interesting that for range of about 6 crank degrees the valve chased the piston, maintaining the same minimum clearance. This looks like plenty of clearance.
I will do the exhaust valve next (even though with the phaser currently advanced it will not be worst case). Then I plan to remove the head and clay the piston to check radial clearance. After that I get to do this all over again with the phaser in the retarded position. I also need to decide if I should do this for the other side of the engine. I am tempted not to with this much clearance, but I'll have to see how close the exhaust valve comes. If I don't check the other side, I will at a minimum check the piston-deck protrusion. I did measure piston-deck protrusion on this side and it was an even .010.
For the record, this is an LY6 370 (4.030 bore x 3.622 stroke) with Wiseco flattop pistons and TSP VVT-2 cam. The block is decked to a 9.240 height and the pistons protrude 0.010. I am using GM MLS gaskets and unmilled LY6 (L92) heads.
crank deg (starting from BTDC) / clearance (in)
4 .270
2 .260
0 .250
2 .235
4 .227
6 .219
8 .210
10 .210
12 .210
14 .210
16 .222
18 .231
20 .245
22 .258
I thought it was interesting that for range of about 6 crank degrees the valve chased the piston, maintaining the same minimum clearance. This looks like plenty of clearance.
I will do the exhaust valve next (even though with the phaser currently advanced it will not be worst case). Then I plan to remove the head and clay the piston to check radial clearance. After that I get to do this all over again with the phaser in the retarded position. I also need to decide if I should do this for the other side of the engine. I am tempted not to with this much clearance, but I'll have to see how close the exhaust valve comes. If I don't check the other side, I will at a minimum check the piston-deck protrusion. I did measure piston-deck protrusion on this side and it was an even .010.
For the record, this is an LY6 370 (4.030 bore x 3.622 stroke) with Wiseco flattop pistons and TSP VVT-2 cam. The block is decked to a 9.240 height and the pistons protrude 0.010. I am using GM MLS gaskets and unmilled LY6 (L92) heads.
10-26-2012, 10:36 AM
#65
More piston-valve clearance results, this time for the exhaust. I think this is very interesting.
Exhaust, Phaser Fully Advanced
crank deg (starting from BTDC) / clearance (in)
24 .304
22 .285
20 .272
18 .260
16 .251
14 .244
12 .239
10 .235
8 .235
6 .236
4 .242
2 .249
0 .257
After obtaining this data, I removed the phaser and locked it into full retard with the Comp Cams limiter in place. Because I had to remove the degree wheel and I left the heads on, I did not have true TDC for the next set of numbers. I did however have the degree wheel on and eyeballed TDC based on the dot facing up on the crank timing sprocket. That allowed me to work in 2 degree increments, but the "0" reference may be off a tad. Here is the data
Exhaust, Phaser Fully Retarded, Comp limiter in place
approx crank deg (BTDC) / clearance (in)
20 .150
18 .144
16 .137
14 .136
12 .135
10 .137
8 .142
6 .150
4 .160
2 .172
0 .188
I find a few things very interesting about the above data. Retarding the cam this much killed about .100 of piston-valve clearance. For the advance position, minimum clearance was .235. For the retarded position, minimum clearance was .135. It's also interesting that for the retarded position, over a range from 20-10degrees BTDC, the clearance changed by only .015in while for the advanced position it changed by .037in. I think this make sense because in the retarded position, the exhaust lobe is probably on the steeper portion of it's closing ramp. It is closing faster so it is able to follow movement of the piston better. For the advance position, the exhaust lobe is on a slower part of it's ramp, so the piston is coming up faster than it's closing.
From what I've read .135 is still considered acceptable, but it makes me wonder about others who are using this cam in LY6 and L99 applications. I don't think those pistons have as much valve relief as the Wisecos I'm running. I will try to get some measurements on my old LY6 pistons to compare.
Something else I'm considering is the limiter block. I actually have in my possession two limiter kits from Comp, one of which was designed for the earlier phasers which had (I think) 10 degrees more travel. In both cases the travel is limited to 20degrees, so I think if I used the old-style limiter in my new-style phaser, I would limit travel from 20 degrees currently to 10 degrees. I think (but need to confirm) these numbers are all in cam degrees; they must be doubled to represent crank degrees. If so, I should currently have 40 crank degrees of timing available and could limit it to 20 crank degrees by using the mismatch combination of spacer & phaser. From the VVT tunes I've seen, it doesn't appear anyone is running anywhere near 20 degrees of retard, so this could work out and give me more piston-valve clearance. I think it's worth a shot.
Exhaust, Phaser Fully Advanced
crank deg (starting from BTDC) / clearance (in)
24 .304
22 .285
20 .272
18 .260
16 .251
14 .244
12 .239
10 .235
8 .235
6 .236
4 .242
2 .249
0 .257
After obtaining this data, I removed the phaser and locked it into full retard with the Comp Cams limiter in place. Because I had to remove the degree wheel and I left the heads on, I did not have true TDC for the next set of numbers. I did however have the degree wheel on and eyeballed TDC based on the dot facing up on the crank timing sprocket. That allowed me to work in 2 degree increments, but the "0" reference may be off a tad. Here is the data
Exhaust, Phaser Fully Retarded, Comp limiter in place
approx crank deg (BTDC) / clearance (in)
20 .150
18 .144
16 .137
14 .136
12 .135
10 .137
8 .142
6 .150
4 .160
2 .172
0 .188
I find a few things very interesting about the above data. Retarding the cam this much killed about .100 of piston-valve clearance. For the advance position, minimum clearance was .235. For the retarded position, minimum clearance was .135. It's also interesting that for the retarded position, over a range from 20-10degrees BTDC, the clearance changed by only .015in while for the advanced position it changed by .037in. I think this make sense because in the retarded position, the exhaust lobe is probably on the steeper portion of it's closing ramp. It is closing faster so it is able to follow movement of the piston better. For the advance position, the exhaust lobe is on a slower part of it's ramp, so the piston is coming up faster than it's closing.
From what I've read .135 is still considered acceptable, but it makes me wonder about others who are using this cam in LY6 and L99 applications. I don't think those pistons have as much valve relief as the Wisecos I'm running. I will try to get some measurements on my old LY6 pistons to compare.
Something else I'm considering is the limiter block. I actually have in my possession two limiter kits from Comp, one of which was designed for the earlier phasers which had (I think) 10 degrees more travel. In both cases the travel is limited to 20degrees, so I think if I used the old-style limiter in my new-style phaser, I would limit travel from 20 degrees currently to 10 degrees. I think (but need to confirm) these numbers are all in cam degrees; they must be doubled to represent crank degrees. If so, I should currently have 40 crank degrees of timing available and could limit it to 20 crank degrees by using the mismatch combination of spacer & phaser. From the VVT tunes I've seen, it doesn't appear anyone is running anywhere near 20 degrees of retard, so this could work out and give me more piston-valve clearance. I think it's worth a shot.
10-26-2012, 11:16 AM
#66
Something else I'm considering is the limiter block. I actually have in my possession two limiter kits from Comp, one of which was designed for the earlier phasers which had (I think) 10 degrees more travel. In both cases the travel is limited to 20degrees, so I think if I used the old-style limiter in my new-style phaser, I would limit travel from 20 degrees currently to 10 degrees. I think (but need to confirm) these numbers are all in cam degrees; they must be doubled to represent crank degrees. If so, I should currently have 40 crank degrees of timing available and could limit it to 20 crank degrees by using the mismatch combination of spacer & phaser. From the VVT tunes I've seen, it doesn't appear anyone is running anywhere near 20 degrees of retard, so this could work out and give me more piston-valve clearance. I think it's worth a shot.
10-26-2012, 11:20 AM
#67
I haven't opened the packaging on the "old style" one yet. What I wrote above is just based on reading. I still need to see.
Which limiter and phaser are you showing in your photo above? Looks the same as mine by eye.
Did you record your phaser travel in cam or crank degrees?
Which limiter and phaser are you showing in your photo above? Looks the same as mine by eye.
Did you record your phaser travel in cam or crank degrees?
10-26-2012, 11:25 AM
#68
"record" it as in the OBD-II Scanner? It listed as "Intake Cam Des Angle" and "Intake Cam Angle" The Des(ired) value seems to track the settings in the tune.
I noticed you put your limiter block in the one vane section that's different than the rest. Did the instructions say to do that, or did you know to, or is it just luck? If you're doing some more testing when you have the test phaser apart again, could you see how much the phaser can rotate with the block in that vane section, vs having the block in one of the other 4 like mine is?
I noticed you put your limiter block in the one vane section that's different than the rest. Did the instructions say to do that, or did you know to, or is it just luck? If you're doing some more testing when you have the test phaser apart again, could you see how much the phaser can rotate with the block in that vane section, vs having the block in one of the other 4 like mine is?
10-26-2012, 11:34 AM
#69
You listed your cam travel as 22 degrees earlier in the post. I didn't know if you recorded that with your degree wheel or assumed it or what.
You're right - my block is in a different position from yours. I put it there based on the photos in the instructions. There is a difference as the timing is limited by the vane section where I put my block. The other vane sections have clearance when moving full advance & retard, so you probably have more travel in your phaser than I do. If you look at the Comp instructions here, step 7 left photo, you can see that they have the limiting vane contacting on the right near the pivot bolt while the adjacent vane to the left has clearance. They put the limiter in the space where I put it.
I'll see what I can measure to quantify the difference for you. Which phaser & spacer combo did you end up using? -358 phaser with 5460 limiter?
You're right - my block is in a different position from yours. I put it there based on the photos in the instructions. There is a difference as the timing is limited by the vane section where I put my block. The other vane sections have clearance when moving full advance & retard, so you probably have more travel in your phaser than I do. If you look at the Comp instructions here, step 7 left photo, you can see that they have the limiting vane contacting on the right near the pivot bolt while the adjacent vane to the left has clearance. They put the limiter in the space where I put it.
I'll see what I can measure to quantify the difference for you. Which phaser & spacer combo did you end up using? -358 phaser with 5460 limiter?
10-26-2012, 11:48 AM
#70
Phaser # 12606358, Comp limiter kit #5460, 189 core Is what I have.
The "22 deg" I used was directly from the install instructions you reference.
"At the same time, by keeping up to 22 degrees of
movement available, all of the wide-open throttle
benefits of the cam phasing can still be retained."
The instructions use "degrees" many times without referencing Cam or Crank, but they also reference "crank degrees" several times also.. If we presume all degrees there are Crank, that would mean we're limited to 11 cam degrees.
The instructions also specify:
"Step 7: Insert the cam phaser limiter block into one
of the cam phaser control chambers; the slotted end
goes in first."
Which seems to indicate to me that it doesn't matter, but now with the data I'm getting and looking more closely at the vanes, the location I put my limiter may be smaller and I'm being limited another 4 cam degrees from what you may see..
While it may not be the end of the world, I purposely put in pistons with deeper reliefs to let me experiment with more cam retard.
The "22 deg" I used was directly from the install instructions you reference.
"At the same time, by keeping up to 22 degrees of
movement available, all of the wide-open throttle
benefits of the cam phasing can still be retained."
The instructions use "degrees" many times without referencing Cam or Crank, but they also reference "crank degrees" several times also.. If we presume all degrees there are Crank, that would mean we're limited to 11 cam degrees.
The instructions also specify:
"Step 7: Insert the cam phaser limiter block into one
of the cam phaser control chambers; the slotted end
goes in first."
Which seems to indicate to me that it doesn't matter, but now with the data I'm getting and looking more closely at the vanes, the location I put my limiter may be smaller and I'm being limited another 4 cam degrees from what you may see..
While it may not be the end of the world, I purposely put in pistons with deeper reliefs to let me experiment with more cam retard.
10-26-2012, 12:04 PM
#71
I think the location you put your limiter shown above would actually put less restriction on movement. I see your logic that the vane seems closer to the block since it has gap to it's right, but if I remember correctly, without a limiter in place, vane next to the pivot bolt restricts the travel in both directions. Without a block, there should be gap in the vane where you put your block in both advance & retard. That gap means you are getting less restriction in movement and therefore more travel. I will try to measure and confirm either way.
I am not sure yet on cam vs. crank degrees, but looking at the images of our phasers above against a protractor, I think you are right - the phaser travel may be 11 deg limited, resulting in 22 crank degrees. I still plan to measure the phaser travel, so I will let you know what I come up with with both blocks in this phaser.
I am not sure yet on cam vs. crank degrees, but looking at the images of our phasers above against a protractor, I think you are right - the phaser travel may be 11 deg limited, resulting in 22 crank degrees. I still plan to measure the phaser travel, so I will let you know what I come up with with both blocks in this phaser.
10-26-2012, 12:04 PM
#72
I wouldn't do that if I were you, especially if you're running
an auto-trans that wouldn't have the same probability of over-rev'ing as my T56..
10-26-2012, 12:09 PM
#73
Great; you and I are dealing with the same part numbers and the same cam, just different pistons and deck protrusion. I'll have to go back and read a bit because I'm still confused on how you intermixed phasers when you were checking your clearance. If we are replicating phaser timing then the Mahle pistons may have deeper reliefs than my Wisecos. It makes sense since the Mahle advertised volume is more than the Wisecos.
10-26-2012, 12:10 PM
#74
The VVT2 tune from TSP requests 8 deg of cam retard at 6800rpms, which would be 16 crank deg. If you further limit yours to 10 degrees with mis-matched limiter blocks, you would be ok up to 5600rpm in their tune (5 cam deg requested) but would flat line from there up.
I wouldn't do that if I were you, especially if you're running
an auto-trans that wouldn't have the same probability of over-rev'ing as my T56..
I wouldn't do that if I were you, especially if you're running
an auto-trans that wouldn't have the same probability of over-rev'ing as my T56..
Last edited by -TheBandit-; 10-26-2012 at 12:23 PM.
10-26-2012, 01:24 PM
#76
I'm 99% sure the tune is in cam degrees. The scanner tracks those numbers exactly and reports them as cam degrees. Also stock L92 tunes have a max value of 30 (for a phaser of 62 crank max, or 31 cam max) and the stock L99 tunes have a max value of 25 (for a phaser of 52 crank max, or 26 cam max)
10-29-2012, 02:44 PM
#77
Thanks mike. That makes sense. I think I will stick to the limiter I have now. It would be nice if Comp made some smaller increment limiter blocks (few degrees) so you could dial back the retard or even limit the advance if you run into clearance issues.
10-30-2012, 11:08 AM
#78
Here is a better photo showing the phaser locked to full advance. You can see I cut off one of the stripped phaser screws (using a bolt cutter). It happened to fit perfectly.
To get the phaser to full retard, I tried random objects from the garage and found a 1/4" hex drive bit was a great fit.
I had to cut the end off because it was a bit long. I took it outside and used a Dremel with a small abrasive cutoff wheel.
Here are the results for the intake valve in full retard. This time I knocked the pointer, so 0 is at least a few degrees off from TDC. I've read a number of places that minimum clearance tends to occur around 10BTDC for exhaust and 10ATDC for intake, which is consistent with my other measurements.
Intake, Phaser Fully Retarded
approx crank deg (BTDC) / clearance (in)
4 .315
2 .310
0 .310
2 .305
4 .305
6 .308
8 .314
In summary, here are my minimum clearances in full advance/full retard
Intake: .210/.305
Exhaust: .235/.135
My next step will be claying the pistons to confirm and check radial clearance. My plan is to put clay on the pistons, install the heads, rotate the crank over (twice min) with the cam full retarded, then remove the phaser, lock it advanced, reinstall the phaser and rotate the crank (twice) again. The resulting indentations should show the worst case for full advance & retard without requiring removal and reinstallation of the heads. Thoughts?
Here is a photo comparing the factory dished LY6 piston to my flattop Wiseco piston. The dish makes it hard to see, but the exhaust valve reliefs are very close to the same depth. That is why limiting the retard travel is critical when using a larger cam, even with an aftermarket piston. The LY6 piston has no intake valve relief beyond the dish, so I'm sure these aftermarket pistons are helping a bit.
To get the phaser to full retard, I tried random objects from the garage and found a 1/4" hex drive bit was a great fit.
I had to cut the end off because it was a bit long. I took it outside and used a Dremel with a small abrasive cutoff wheel.
Here are the results for the intake valve in full retard. This time I knocked the pointer, so 0 is at least a few degrees off from TDC. I've read a number of places that minimum clearance tends to occur around 10BTDC for exhaust and 10ATDC for intake, which is consistent with my other measurements.
Intake, Phaser Fully Retarded
approx crank deg (BTDC) / clearance (in)
4 .315
2 .310
0 .310
2 .305
4 .305
6 .308
8 .314
In summary, here are my minimum clearances in full advance/full retard
Intake: .210/.305
Exhaust: .235/.135
My next step will be claying the pistons to confirm and check radial clearance. My plan is to put clay on the pistons, install the heads, rotate the crank over (twice min) with the cam full retarded, then remove the phaser, lock it advanced, reinstall the phaser and rotate the crank (twice) again. The resulting indentations should show the worst case for full advance & retard without requiring removal and reinstallation of the heads. Thoughts?
Here is a photo comparing the factory dished LY6 piston to my flattop Wiseco piston. The dish makes it hard to see, but the exhaust valve reliefs are very close to the same depth. That is why limiting the retard travel is critical when using a larger cam, even with an aftermarket piston. The LY6 piston has no intake valve relief beyond the dish, so I'm sure these aftermarket pistons are helping a bit.
10-30-2012, 07:21 PM
#79
Is there anyway to get around this vvt....this all new to me...what if i went carbed or does this need to be ran.....got a good deal on a 08 6.2....trying to see if its even worth picking up..