Did I put in the correct length pushrods?
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
Did I put in the correct length pushrods? When tuning on the street it really feels like the power is falling off huge between 6000 and 7000 RPM. I requested Patrick G spec the cam based upon shifting at 7200RPM. No dyno yet.
- Block decked .020
- PRC 5.3L heads requested to be milled to 59cc, found they were 62cc (even though it appears they already took .020 off based upon the bolt boss thickness) and milled another .020 off to reach 59cc
- Cometic .040 gaskets
- stock rockers shimmed .020 (I think?) for wipe pattern
- Cadillac Racing lifters
- Cam is a 22x/23x .6xx/.6xx, 110+2, LSK lobes, degreed in using ICL method
- I'm not sure what else is part of the equation
7.400 pushrods, 3/8"x.080 wall, were chosen based upon how it felt as well as using a Crane pushrod length checker. I'm just wondering if somehow we got the measurements wrong and that would account for the fall off up top. I have a Comp Cams pushrod checker at my disposal, but I'm not sure what preload to use for the Caddy lifters. Any guesses what range I should be in and/or a good pushrod length checking tutorial?
- Block decked .020
- PRC 5.3L heads requested to be milled to 59cc, found they were 62cc (even though it appears they already took .020 off based upon the bolt boss thickness) and milled another .020 off to reach 59cc
- Cometic .040 gaskets
- stock rockers shimmed .020 (I think?) for wipe pattern
- Cadillac Racing lifters
- Cam is a 22x/23x .6xx/.6xx, 110+2, LSK lobes, degreed in using ICL method
- I'm not sure what else is part of the equation
7.400 pushrods, 3/8"x.080 wall, were chosen based upon how it felt as well as using a Crane pushrod length checker. I'm just wondering if somehow we got the measurements wrong and that would account for the fall off up top. I have a Comp Cams pushrod checker at my disposal, but I'm not sure what preload to use for the Caddy lifters. Any guesses what range I should be in and/or a good pushrod length checking tutorial?
When tuning on the street it really feels like the power is falling off huge between 6000 and 7000 RPM. I requested Patrick G spec the cam based upon shifting at 7200RPM. No dyno yet.
- Block decked .020
- PRC 5.3L heads requested to be milled to 59cc, found they were 62cc (even though it appears they already took .020 off based upon the bolt boss thickness) and milled another .020 off to reach 59cc
- Cometic .040 gaskets
- stock rockers shimmed .020 (I think?) for wipe pattern
- Cadillac Racing lifters
- Cam is a 22x/23x .6xx/.6xx, 110+2, LSK lobes, degreed in using ICL method
- I'm not sure what else is part of the equation
7.400 pushrods, 3/8"x.080 wall, were chosen based upon how it felt as well as using a Crane pushrod length checker. I'm just wondering if somehow we got the measurements wrong and that would account for the fall off up top. I have a Comp Cams pushrod checker at my disposal, but I'm not sure what preload to use for the Caddy lifters. Any guesses what range I should be in and/or a good pushrod length checking tutorial?
- Block decked .020
- PRC 5.3L heads requested to be milled to 59cc, found they were 62cc (even though it appears they already took .020 off based upon the bolt boss thickness) and milled another .020 off to reach 59cc
- Cometic .040 gaskets
- stock rockers shimmed .020 (I think?) for wipe pattern
- Cadillac Racing lifters
- Cam is a 22x/23x .6xx/.6xx, 110+2, LSK lobes, degreed in using ICL method
- I'm not sure what else is part of the equation
7.400 pushrods, 3/8"x.080 wall, were chosen based upon how it felt as well as using a Crane pushrod length checker. I'm just wondering if somehow we got the measurements wrong and that would account for the fall off up top. I have a Comp Cams pushrod checker at my disposal, but I'm not sure what preload to use for the Caddy lifters. Any guesses what range I should be in and/or a good pushrod length checking tutorial?
I would think the chassis dyno would be the best tool here. Im sure you could gain access to one and for less than $100 get a few pulls on it to see what exactly is going on. Trying to use the SOTP method is not going to work although it seems it certainly alerted you to a potential problem.
How much seat and open pressure are those springs? What is the spring rate?
LSK lobes need some stout pressures to keep the roller glued to the cam lobe...
My advise is to hit the dyno so you can post the gragh....lets see whats really going on
Tony
How much seat and open pressure are those springs? What is the spring rate?
LSK lobes need some stout pressures to keep the roller glued to the cam lobe...
My advise is to hit the dyno so you can post the gragh....lets see whats really going on
Tony
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Joined: May 2007
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7200 rpm with that ICL. Hmm not really happening.
When tuning on the street it really feels like the power is falling off huge between 6000 and 7000 RPM. I requested Patrick G spec the cam based upon shifting at 7200RPM. No dyno yet.
- Block decked .020
- PRC 5.3L heads requested to be milled to 59cc, found they were 62cc (even though it appears they already took .020 off based upon the bolt boss thickness) and milled another .020 off to reach 59cc
- Cometic .040 gaskets
- stock rockers shimmed .020 (I think?) for wipe pattern
- Cadillac Racing lifters
- Cam is a 22x/23x .6xx/.6xx, 110+2, LSK lobes, degreed in using ICL method
- I'm not sure what else is part of the equation
7.400 pushrods, 3/8"x.080 wall, were chosen based upon how it felt as well as using a Crane pushrod length checker. I'm just wondering if somehow we got the measurements wrong and that would account for the fall off up top. I have a Comp Cams pushrod checker at my disposal, but I'm not sure what preload to use for the Caddy lifters. Any guesses what range I should be in and/or a good pushrod length checking tutorial?
- Block decked .020
- PRC 5.3L heads requested to be milled to 59cc, found they were 62cc (even though it appears they already took .020 off based upon the bolt boss thickness) and milled another .020 off to reach 59cc
- Cometic .040 gaskets
- stock rockers shimmed .020 (I think?) for wipe pattern
- Cadillac Racing lifters
- Cam is a 22x/23x .6xx/.6xx, 110+2, LSK lobes, degreed in using ICL method
- I'm not sure what else is part of the equation
7.400 pushrods, 3/8"x.080 wall, were chosen based upon how it felt as well as using a Crane pushrod length checker. I'm just wondering if somehow we got the measurements wrong and that would account for the fall off up top. I have a Comp Cams pushrod checker at my disposal, but I'm not sure what preload to use for the Caddy lifters. Any guesses what range I should be in and/or a good pushrod length checking tutorial?
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Good call....
Neither the duration, the LSA, or the ICL is condusive to that RPM....
Mid 230's on the intake lobe and at least a 113 ICL (or even 114) with little or no advance would have been better suited for that job. Or a 112 with even more duration might have done it. Also, airflow is at a premium here (as is valvetrain weight and stability) and the entire package from the CAI to the exhaust tips would need to be optimized to allow the engine to hang on like that with a hyd. roller.
That small a cam on a 110 probably peaks in the low 6000's and is falling off a cliff by 6800
Once again however....why bother guessing when a dyno gragh is worth 1000 words as they say.
Tony
Neither the duration, the LSA, or the ICL is condusive to that RPM....
Mid 230's on the intake lobe and at least a 113 ICL (or even 114) with little or no advance would have been better suited for that job. Or a 112 with even more duration might have done it. Also, airflow is at a premium here (as is valvetrain weight and stability) and the entire package from the CAI to the exhaust tips would need to be optimized to allow the engine to hang on like that with a hyd. roller.
That small a cam on a 110 probably peaks in the low 6000's and is falling off a cliff by 6800
Once again however....why bother guessing when a dyno gragh is worth 1000 words as they say.
Tony
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Joined: May 2007
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Having dynoed this camshaft before I have no problem saying its out steam at 6300. In fact most of the stuff out there is. I have found some ways to get the ls6 intakes to go to 7k but I ain't giving that info out.
Good call....
Neither the duration nor the LSA is condusive to that RPM....
Mid 230's on the intake lobe and at least a 113 ICL (or even 114) with little or no advance would have been better suited for that job.
That small a cam on a 110 probably peaks in the low 6000's and is falling off a cliff by 6800
Once again however....why bother guessing when a dyno gragh is worth 1000 words as they say.
Tony
Neither the duration nor the LSA is condusive to that RPM....
Mid 230's on the intake lobe and at least a 113 ICL (or even 114) with little or no advance would have been better suited for that job.
That small a cam on a 110 probably peaks in the low 6000's and is falling off a cliff by 6800
Once again however....why bother guessing when a dyno gragh is worth 1000 words as they say.
Tony
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
I would think the chassis dyno would be the best tool here. Im sure you could gain access to one and for less than $100 get a few pulls on it to see what exactly is going on. Trying to use the SOTP method is not going to work although it seems it certainly alerted you to a potential problem.
How much seat and open pressure are those springs? What is the spring rate?
LSK lobes need some stout pressures to keep the roller glued to the cam lobe...
My advise is to hit the dyno so you can post the gragh....lets see whats really going on
Tony
How much seat and open pressure are those springs? What is the spring rate?
LSK lobes need some stout pressures to keep the roller glued to the cam lobe...
My advise is to hit the dyno so you can post the gragh....lets see whats really going on
Tony
Regarding the cam design, I don't know what to say. Pat has a good reputation and I told him I wanted to shift at 7200 to take advantage of mechanical gearing, but I also wanted to lower my torque curve for autox/RR. The cam doctor specs are here: https://ls1tech.com/forums/showpost....59&postcount=6
Last edited by JimMueller; Nov 10, 2007 at 10:43 PM.
The larger issue here is your request was unrealistic....in a sense almost at the opposite end of the spectrum. One is aimed at high RPM power and the other is concerned with low RPM TQ to help explode a car out of a slow corner. Kind of like asking for a cam that will turn 7200 and idle like a stocker. The reality is a combination like that doesn't exist....not until our beloved LS1's have V-Tec.....LOL
Regards,
Tony
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
It didn't need to make great power above 6K, but I am hoping it doesn't fall off horribly. I'm heading to the dyno today and have another scheduled next week if I need to change pushrods.
I think I have the math right, but obviously it still needs to be checked. I'm not clear if the base circle is different between intake & exhaust on a LSK cam. Maybe those threads which indicated the exhaust was different had different lobes.
StockPR+RockerShim-(StockGasketCompressed-NewGasketThickness)-HeadMill-BlockMill+Preload+((StockBaseCircle-BaseCircle)/2)
I come up with 7.4 before compensating for the base circle. The change in the base circle radius is .0785, so from a math perspective I come up with a 7.4785" pushrod, which I would round down to 7.475. If that is the case, what symptoms may I notice from a pushrod that is .075 too short?
I think I have the math right, but obviously it still needs to be checked. I'm not clear if the base circle is different between intake & exhaust on a LSK cam. Maybe those threads which indicated the exhaust was different had different lobes.
Code:
Stock pushrod length 7.398 Rocker arm shim 0.020 Stock Gasket thickness 0.056 My gasket 0.040 Head milled 0.042 Engine block milled 0.020 Requested lifter preload 0.060 Stock Base circle 1.552 LSK base circle 1.395 Estimated Pushrod length 7.4785
I come up with 7.4 before compensating for the base circle. The change in the base circle radius is .0785, so from a math perspective I come up with a 7.4785" pushrod, which I would round down to 7.475. If that is the case, what symptoms may I notice from a pushrod that is .075 too short?
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
OK, here's 3 pulls from today at Norris Motorsports. We didn't feel it fall over at all on the dyno 
These are by no means completely tuned, just a baseline and some quick adjustments.
Pull 1: Baseline. Low timing but logging wrong PID to determine where to adjust. AFR was set ~12.5 below torque peak and about 13 above. VE isn't quite polished yet to yield what I command. 3-4* of constant KR at WOT.
Pull 2: Set commanded AFR to 13 across the board and this time we could see what was going on with the spark. 19-25* from 2400->4400. 3-4* of constant KR at WOT.
Pull 3: Put in some mid-to-upper 20's advance values to get in the ballpark. Temporarily altered max KR table.
Pull 1
Pull 2
Pull 3
Thoughts.... I like the curves, but I'm hoping theres more in it with just tuning. I'll run a tank of 104 to confirm the KR is false. Assuming it is I'll have to decide how I want to deal with it.
These are by no means completely tuned, just a baseline and some quick adjustments.Pull 1: Baseline. Low timing but logging wrong PID to determine where to adjust. AFR was set ~12.5 below torque peak and about 13 above. VE isn't quite polished yet to yield what I command. 3-4* of constant KR at WOT.
Pull 2: Set commanded AFR to 13 across the board and this time we could see what was going on with the spark. 19-25* from 2400->4400. 3-4* of constant KR at WOT.
Pull 3: Put in some mid-to-upper 20's advance values to get in the ballpark. Temporarily altered max KR table.
Pull 1
Pull 2
Pull 3
Thoughts.... I like the curves, but I'm hoping theres more in it with just tuning. I'll run a tank of 104 to confirm the KR is false. Assuming it is I'll have to decide how I want to deal with it.
11 Second Club
Joined: May 2004
Posts: 226
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From: Va. beach,Va
It didn't need to make great power above 6K, but I am hoping it doesn't fall off horribly. I'm heading to the dyno today and have another scheduled next week if I need to change pushrods.
I think I have the math right, but obviously it still needs to be checked. I'm not clear if the base circle is different between intake & exhaust on a LSK cam. Maybe those threads which indicated the exhaust was different had different lobes.
StockPR+RockerShim-(StockGasketCompressed-NewGasketThickness)-HeadMill-BlockMill+Preload+((StockBaseCircle-BaseCircle)/2)
I come up with 7.4 before compensating for the base circle. The change in the base circle radius is .0785, so from a math perspective I come up with a 7.4785" pushrod, which I would round down to 7.475. If that is the case, what symptoms may I notice from a pushrod that is .075 too short?
I think I have the math right, but obviously it still needs to be checked. I'm not clear if the base circle is different between intake & exhaust on a LSK cam. Maybe those threads which indicated the exhaust was different had different lobes.
Code:
Stock pushrod length 7.398 Rocker arm shim 0.020 Stock Gasket thickness 0.056 My gasket 0.040 Head milled 0.042 Engine block milled 0.020 Requested lifter preload 0.060 Stock Base circle 1.552 LSK base circle 1.395 Estimated Pushrod length 7.4785
I come up with 7.4 before compensating for the base circle. The change in the base circle radius is .0785, so from a math perspective I come up with a 7.4785" pushrod, which I would round down to 7.475. If that is the case, what symptoms may I notice from a pushrod that is .075 too short?
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
The top-end is a little rough with smoothing=0, but not jagged like I'd expect with a valvetrain issue. So I'm wondering if the math above is wrong, or what other factors would cause a 7.4" pushrod to work correctly if the math says it needs another .075. Can there be that much tolerance?
Joined: Nov 2001
Posts: 3,043
Likes: 0
From: Texas and Qatar
It would be easier, quicker and most important: more accurate to just use a pushrod length checker. I've never been a fan of calculating pushrod length by measurements (that the setup is "supposed" to be). You're also missing a few calculations such as valve depth and possible slight valve tip length differences from a stock head. I've also seen lifter total length differences between Comp lifters and OEM lifters as an example that needed different pushrods just by a lifter swap.
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
I got a late start on it today and will try again tomorrow since I have to replace a knock sensor also. My measurement today was 8.5 turns, so 8.5*0.050=0.425+6.800=7.225+.060=7.285.
Any tricks to keeping the bottom section of the checker from turning?
Any tricks to keeping the bottom section of the checker from turning?
Joined: Nov 2001
Posts: 3,043
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From: Texas and Qatar
That sounds way too short, are sure the lifter is on the basecircle of the cam? What I do is turn the motor over by hand (clockwise) until the intake rocker is closing, then bring that piston to TDC and that cylinder will have both lifters on the basecircle of the cam. That where you need to check lifter length and preload. I've had to pull the rocker off to make that adj. on those pushrods, isn't there measurement lines on it that indicate how many turns?