Need help with valvetrain choice!
03-08-2003, 01:50 PM
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Need help with valvetrain choice! Hey guys, I just sent my money out for a Comp 228 XE-R (228/228 .588/.588 112). I am going to buy Comp 918 valvesprings, and have a few questions. I was lookin on Scoggin Dickey's website, and they seem to have some pretty good deals. They have Manley Chromemoly pushrods 16 for $92. I was wondering if those pushrods are as good as the Comp pushrods, cuz if they are, I will buy those. Also, I don't know what size I need. I'm assuming I would need the stock length, but not sure. And then I was also looking at the Manley Titanium Retainers cuz they are a lot cheaper than the Comp Titanium Retainers. But I am not sure which one's are the right one's, and I don't know if they work with the Comp 918 springs. Here are the two Ti retainers they have:
1. 1.155 O.D. Titanium Retainers for LS1
Price: $89.50
Part # MAN23632-16
Titanium retainers made specifically for the LS1 and LS6 factory stem diameter and the GM valve locks. Designed for the SD1423 valve spring, however this retainer will fit most 1.255" OD springs. The inner id of the retainer is 0.828". For most applications this retainer will set the spring at the factory "installed height".
2. 1.155 O.D. +0.050" Titanium Retainers for LS1
Price: $94.75
Part # MAN23633-16
Titanium retainers made specifically for the LS1 and LS6 factory stem diameter and the GM valve locks. Designed for the SD1423 valve spring, however this retainer will fit most 1.255" OD springs. The inner id of the retainer is 0.828". This retainer is designed to increase the valve spring installed height by 0.050".
Sorry about the long post, but i'm just trying to put together a good valvetrain setup for my cam at the best price!! Please let me know what you guys think, and what combo to use. Thanks in advance for any help you guys can give me!!! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
1. 1.155 O.D. Titanium Retainers for LS1
Price: $89.50
Part # MAN23632-16
Titanium retainers made specifically for the LS1 and LS6 factory stem diameter and the GM valve locks. Designed for the SD1423 valve spring, however this retainer will fit most 1.255" OD springs. The inner id of the retainer is 0.828". For most applications this retainer will set the spring at the factory "installed height".
2. 1.155 O.D. +0.050" Titanium Retainers for LS1
Price: $94.75
Part # MAN23633-16
Titanium retainers made specifically for the LS1 and LS6 factory stem diameter and the GM valve locks. Designed for the SD1423 valve spring, however this retainer will fit most 1.255" OD springs. The inner id of the retainer is 0.828". This retainer is designed to increase the valve spring installed height by 0.050".
Sorry about the long post, but i'm just trying to put together a good valvetrain setup for my cam at the best price!! Please let me know what you guys think, and what combo to use. Thanks in advance for any help you guys can give me!!! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
03-08-2003, 05:00 PM
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Re: Need help with valvetrain choice! Anyone have any ideas? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
03-09-2003, 08:18 AM
#4
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Re: Need help with valvetrain choice! Since you are not getting any replies, I will at least give you my 2 cents:
1. All the hardened chromemoly pushrods are the same. I installed Thunder Racing pushrods in my engine since I was purchasing a cam at the same time. The rods you are interested in would be just as good as Comp Cams, etc
2. I believe titanium retainers are a waste of money on an LS1 that will never see above 6,600 revs. Additionally, the LS1 retainers are very small in comparison to lets say big block chev or MOPAR retainers. Do to there small size, the wieght savings of a titanium retainer is insignificant when used with 918 springs.
3. If you are still set on purchasing titanium retainers for the 918 springs, I would go with the stock spec MAN23632-16 retainers. This will yield about a 1.80" install height if just dropped in. As per Comp Cams literature, they are not supposed to get into coil bind with the cam you will be using. If you install the other retainers, you will loose lots of valve seat pressure due the increased install height they will give you. Again, if you have no problem with coil bind, there is no reason to purchase those.
Personally, (and only my preference), I would look for a cam with a little less lift. Those XE-R lobes will greatly reduce the service life of your springs and make for a very noisey valvetrain. But, thats up to you. A lift in the area of .550" - .565" is a lot easier on the springs with very little tradeoff in HP. I hope you are going to go with a set of Stage 2 heads to take advantage of that cam. If not, you may want a little less cam in it. A little less duration will give the car better throttle response and a flatter torque curve (which is a plus in a daily driver)
Just my opinions,
Hope it helps
Ron
1. All the hardened chromemoly pushrods are the same. I installed Thunder Racing pushrods in my engine since I was purchasing a cam at the same time. The rods you are interested in would be just as good as Comp Cams, etc
2. I believe titanium retainers are a waste of money on an LS1 that will never see above 6,600 revs. Additionally, the LS1 retainers are very small in comparison to lets say big block chev or MOPAR retainers. Do to there small size, the wieght savings of a titanium retainer is insignificant when used with 918 springs.
3. If you are still set on purchasing titanium retainers for the 918 springs, I would go with the stock spec MAN23632-16 retainers. This will yield about a 1.80" install height if just dropped in. As per Comp Cams literature, they are not supposed to get into coil bind with the cam you will be using. If you install the other retainers, you will loose lots of valve seat pressure due the increased install height they will give you. Again, if you have no problem with coil bind, there is no reason to purchase those.
Personally, (and only my preference), I would look for a cam with a little less lift. Those XE-R lobes will greatly reduce the service life of your springs and make for a very noisey valvetrain. But, thats up to you. A lift in the area of .550" - .565" is a lot easier on the springs with very little tradeoff in HP. I hope you are going to go with a set of Stage 2 heads to take advantage of that cam. If not, you may want a little less cam in it. A little less duration will give the car better throttle response and a flatter torque curve (which is a plus in a daily driver)
Just my opinions,
Hope it helps
Ron
03-09-2003, 08:32 AM
#5
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Re: Need help with valvetrain choice! I don't know what the base circle is on the cam you want to use, but the below info will make pushrod length selection a little clearer. You more than likely be able to get by with stock 7.40" length rods. Certainly, you DONT want shorter rods.
________________________________________________
LS1 CAM BASE CIRCLE INFO:
The aftermarket cams being installed today will usually have a smaller base circle than the stock LS1 cam they are replacing. Base Circle is actually the distance accross the cam's lobe. This is 90 degrees from the top of the cam's lobe at the point of highest lift.
You can easily measure this base circle distance with a micrometer. Measure across the cam's lobe (the lobe's smallest distance across). You will find that it is 1.552” on a stock LS1 cam. You will need to cut this distance in half in order to get the cams "centerline to lobe heal" distance. The stock LS1 cam has a .776" centerline to lobe heal distance (19.7mm).
This centerline to lobe heal distance is what is important to you in determining lifter preload.
A TR-220 cam has a 1.502” across the lobe base circle. Cutting this number also in half will equal a 0.751” centerline to heel distance. This is a 025" smaller centerline to lobe heal distance than the stock cam.
To be very accurate, you would then need a pushrod that is .025" longer than stock to achieve the same spec lifter preload as you had with your stock cam.
These aftermarket pushrods come in .050" length increments, so in this case, a stock 7.40” pushrod would be ok.
Remember, hydraulic lifters, due to there design have a + - preload variance that the lifter can operate within. It don't need to be exact. Just get it as close as possible with the various pushrods that are available (in .050" increments)
Be advised, milling the heads will change all this and require shorter pushrods equal to how much is milled off the heads (see below).
So, to re-iterate all this:
1. If your cam has a .025" smaller centerline to lobe heal distance than stock, you would need a .025" [longer] rod.
2. If you just milled the heads .025", you would need a .025" [shorter] rod.
3. Combine the two, and your stock 7.40" pushrod would be perfect … It then becomes “tit for tat”
________________________________________________
CHECKING LIFTER PRELOAD:
1. Turning the engine, bring the EXHAUST valve on one of the cylinders down until it is at peak lift (valve fully open). The pushrod will be pushed all the way down and the valve spring will be compressed.
2. Now, fully loosen the rocker arm bolt on the INTAKE of that cyl. (this valve will be fully closed).
3. Then turn that INTAKE rocker arm bolt down until the lifter is at "zero lash". You will be able to tell it is at zero lash when the rocker bolt gets very hard to turn. It gets hard to turn because the valve spring starts to compress. Again, stop turning the bolt as soon as you feel resistance to turning.
4. Mark the bolt with a marker.
5. Now count how many turns it takes to completely tighten the rocker bolt to 22 FT/LB.
The bolt should have turned between 1 3/4 to 2 turns for the acceptable GM lifter peload.
If you don't get the 1 3/4 to 2 bolt turns of preload, you need a different length pushrod. (IE: longer rod if it takes much more than 2 turns, and a shorter rod if it takes much less than 1 3/4 turns).
NOTE: You really only need to do this on one cylinder. The rest will be the same.
NOTE: If you have aftermarket Comp Cams “Type R” lifters, I understand that those like less preload than stock lifters. Instead of 1 3/4 to 2 full turns as indicated above, 1 to 1 1/4 turn may be better. Check with Comp Cams on there actual required preload.
________________________________________________
LS1 CAM BASE CIRCLE INFO:
The aftermarket cams being installed today will usually have a smaller base circle than the stock LS1 cam they are replacing. Base Circle is actually the distance accross the cam's lobe. This is 90 degrees from the top of the cam's lobe at the point of highest lift.
You can easily measure this base circle distance with a micrometer. Measure across the cam's lobe (the lobe's smallest distance across). You will find that it is 1.552” on a stock LS1 cam. You will need to cut this distance in half in order to get the cams "centerline to lobe heal" distance. The stock LS1 cam has a .776" centerline to lobe heal distance (19.7mm).
This centerline to lobe heal distance is what is important to you in determining lifter preload.
A TR-220 cam has a 1.502” across the lobe base circle. Cutting this number also in half will equal a 0.751” centerline to heel distance. This is a 025" smaller centerline to lobe heal distance than the stock cam.
To be very accurate, you would then need a pushrod that is .025" longer than stock to achieve the same spec lifter preload as you had with your stock cam.
These aftermarket pushrods come in .050" length increments, so in this case, a stock 7.40” pushrod would be ok.
Remember, hydraulic lifters, due to there design have a + - preload variance that the lifter can operate within. It don't need to be exact. Just get it as close as possible with the various pushrods that are available (in .050" increments)
Be advised, milling the heads will change all this and require shorter pushrods equal to how much is milled off the heads (see below).
So, to re-iterate all this:
1. If your cam has a .025" smaller centerline to lobe heal distance than stock, you would need a .025" [longer] rod.
2. If you just milled the heads .025", you would need a .025" [shorter] rod.
3. Combine the two, and your stock 7.40" pushrod would be perfect … It then becomes “tit for tat”
________________________________________________
CHECKING LIFTER PRELOAD:
1. Turning the engine, bring the EXHAUST valve on one of the cylinders down until it is at peak lift (valve fully open). The pushrod will be pushed all the way down and the valve spring will be compressed.
2. Now, fully loosen the rocker arm bolt on the INTAKE of that cyl. (this valve will be fully closed).
3. Then turn that INTAKE rocker arm bolt down until the lifter is at "zero lash". You will be able to tell it is at zero lash when the rocker bolt gets very hard to turn. It gets hard to turn because the valve spring starts to compress. Again, stop turning the bolt as soon as you feel resistance to turning.
4. Mark the bolt with a marker.
5. Now count how many turns it takes to completely tighten the rocker bolt to 22 FT/LB.
The bolt should have turned between 1 3/4 to 2 turns for the acceptable GM lifter peload.
If you don't get the 1 3/4 to 2 bolt turns of preload, you need a different length pushrod. (IE: longer rod if it takes much more than 2 turns, and a shorter rod if it takes much less than 1 3/4 turns).
NOTE: You really only need to do this on one cylinder. The rest will be the same.
NOTE: If you have aftermarket Comp Cams “Type R” lifters, I understand that those like less preload than stock lifters. Instead of 1 3/4 to 2 full turns as indicated above, 1 to 1 1/4 turn may be better. Check with Comp Cams on there actual required preload.
