What pushrod length for 232/236 LSK??
03-29-2007, 12:41 PM
#1
What pushrod length for 232/236 LSK?? Specs....232/236 .643/.646 110+2 LSK lobes
Right now I have 7.350" pushrods with my TREX V2 and 853 heads that have been milled ~0.070". Comp R lifters and stock rocker arms. Valve train is nice and quiet and doesnt sound like a sewing machine...but I read that the LSK lobes are a smaller base circle than XER's, so what length would I need here? Also, should I shim my valve springs? I have PRC Platinum dual springs that are still as stiff as they ever were and I have never had any valve float issues with them.
Right now I have 7.350" pushrods with my TREX V2 and 853 heads that have been milled ~0.070". Comp R lifters and stock rocker arms. Valve train is nice and quiet and doesnt sound like a sewing machine...but I read that the LSK lobes are a smaller base circle than XER's, so what length would I need here? Also, should I shim my valve springs? I have PRC Platinum dual springs that are still as stiff as they ever were and I have never had any valve float issues with them.
03-29-2007, 12:55 PM
#2
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You NEED to use a pushrod checking tool to actually measure what size you need. We can not guess what size you need because you have too many parts changed from stock.
Yes the LSK lobe base is smaller so you will need a longer PR. lso keep in mind those lifters need to be run with a very low preload, .002-.004.
Order a pushrod checker, it is only $20 and will tell you the exact size you need.
Yes the LSK lobe base is smaller so you will need a longer PR. lso keep in mind those lifters need to be run with a very low preload, .002-.004.
Order a pushrod checker, it is only $20 and will tell you the exact size you need.
03-29-2007, 11:06 PM
#3
All I basicly need to know is how much smaller the base circle on this cam will be versus my TREX V2 which is also ground by Comp. So lets assume I have stock unmilled heads and stock 7.400" pushrods. How much longer would my new pushrods have to be over stock? Right now with my setup, I have 0.020" preload for my lifters, which has made my motor quieter than any other big cam motor I have heard around here anyway.
03-29-2007, 11:59 PM
#5
Its twenty thousandths preload = 0.020"
I believe brad8266 got his numbers backwards. I talked to Comps tech people and they told me 0.020" preload was good and that stock rocker arms would work just fine as long as the preload was correct. I have 9,000 + miles on my motor with Comp R lifters and this preload with a TREX V2 and my motor is very quiet and does not sound like a sewing machine like alot of other big cam cars. My dyno numbers are in my sig...looks to me everything is working fine here.
I believe brad8266 got his numbers backwards. I talked to Comps tech people and they told me 0.020" preload was good and that stock rocker arms would work just fine as long as the preload was correct. I have 9,000 + miles on my motor with Comp R lifters and this preload with a TREX V2 and my motor is very quiet and does not sound like a sewing machine like alot of other big cam cars. My dyno numbers are in my sig...looks to me everything is working fine here.
03-30-2007, 12:14 AM
#6
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hey, moe,
i spoke to compcams earlier today and they told me three thousands (.003") after warming up the engine, and their instructions site says .002-.004" in this link http://www.compcams.com/Technical/In.../Files/160.pdf
but, you HAVE THEM and are using them, so you tell me, bro, b/c i will be installing them.
i spoke to compcams earlier today and they told me three thousands (.003") after warming up the engine, and their instructions site says .002-.004" in this link http://www.compcams.com/Technical/In.../Files/160.pdf
but, you HAVE THEM and are using them, so you tell me, bro, b/c i will be installing them.
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03-30-2007, 10:04 AM
#8
The part # for Comp R's is 875-16. It was not listed in the part #'s for the lifter preload specs you just posted up. Those are not the right specs. And by the way, I turn my motor 7200 rpms and spray anywhere from 100 to 200 shot of nitrous and never had a problem with the lifters and never had trouble with noise. Like I said though, I talked to a tech person back when I did my motor a year ago. They may have changed the specs...but 0.020" is what it was when I did my motor and things are great with it, except that I am gonna change cams.
03-30-2007, 10:08 AM
#9
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875-16's take .002-.004 preload, read the install document.
http://www.compcams.com/Technical/In.../Files/160.pdf
I never said anything about needing aftermarket rockers, all you need are shorter PR's to get to proper preload with stock rockers. My numbers arent backwards.
Aftermarket rockers may help though to ensure a good valve stem wipe pattern.
http://www.compcams.com/Technical/In.../Files/160.pdf
I never said anything about needing aftermarket rockers, all you need are shorter PR's to get to proper preload with stock rockers. My numbers arent backwards.
Aftermarket rockers may help though to ensure a good valve stem wipe pattern.
03-30-2007, 10:13 AM
#10
I read the one down below...ok its on there. But like I said...I went on what they told me on the phone and have over 9,000 miles on the motor. No sewing machine noises, no lifter issues at all.
Can we get back to my DAMN question about the Base Circle of LSK lobe cam please. Thats what this thread was for anyway.....
Can we get back to my DAMN question about the Base Circle of LSK lobe cam please. Thats what this thread was for anyway.....
03-30-2007, 04:14 PM
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((1.553-1.395)/2)+7.39 stock PR+.003 preload+.052 stock gasket -.070 mill= 7.454
A 7.450 PR will do the trick for ya even if you have a .040 head gasket.
A 7.450 PR will do the trick for ya even if you have a .040 head gasket.
03-30-2007, 04:32 PM
#15
OK...now we are gettin somewhere. I have the stock GM graphite gaskets. With my heads being milled so much, I didnt want to take any chances, and I had read alot of people having great luck with the graphite gaskets holding big power.
7.3725" pushrods...can you get that length?? HAHA, thanks guys. I wanna have everything here and ready to go so my car isnt down while I get more stuff. I appreciate the help.
7.3725" pushrods...can you get that length?? HAHA, thanks guys. I wanna have everything here and ready to go so my car isnt down while I get more stuff. I appreciate the help.
03-30-2007, 04:41 PM
#16
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Originally Posted by moeZ28
OK...now we are gettin somewhere. I have the stock GM graphite gaskets. With my heads being milled so much, I didnt want to take any chances, and I had read alot of people having great luck with the graphite gaskets holding big power.
7.3725" pushrods...can you get that length?? HAHA, thanks guys. I wanna have everything here and ready to go so my car isnt down while I get more stuff. I appreciate the help.
7.3725" pushrods...can you get that length?? HAHA, thanks guys. I wanna have everything here and ready to go so my car isnt down while I get more stuff. I appreciate the help.
03-30-2007, 04:55 PM
#17
On a stock setup yes...but remember I dont have a stock setup...I was gonna use your info and plug in my stuff and get the numbers right...which is what cws t/a already did when he got 7.3725". I am gonna go with a 7.373" pushrod. I dont think .0005" will make any difference.
This is the same as what I got starting out with a 7.350" pushrod which is what I actually have. brad8266 - your numbers were right for a stock setup, which is what I asked for so thanks for showing me the correct math.
This is the same as what I got starting out with a 7.350" pushrod which is what I actually have. brad8266 - your numbers were right for a stock setup, which is what I asked for so thanks for showing me the correct math.
03-30-2007, 04:57 PM
#18
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I can see what youre trying to do by just taking the difference of the base circles and adjusting your pr by that amount.
Just do the smart thing and get a checker because you dont really know if your current pr are the right length. Its like $20, just go buy one and be done with it, guessing games with engines are stupid
Just do the smart thing and get a checker because you dont really know if your current pr are the right length. Its like $20, just go buy one and be done with it, guessing games with engines are stupid
03-30-2007, 04:59 PM
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I gave you numbers for going with the setup you currently have, LSk lobes, r lifters, stock gaskets, and milled heads. Youre coming up short man but whatever its your call it isnt my car.
The 7.350 rods you already have arent even the right size for your current setup so your **** is still going to be off.
7.4315 should be your current PR size with your TREX cam.
The 7.350 rods you already have arent even the right size for your current setup so your **** is still going to be off.
7.4315 should be your current PR size with your TREX cam.
03-30-2007, 05:09 PM
#20
Its not guessing...I know my pushrods are right now. You can see where the wear is on top of the brand new valves I put in the heads when I built the motor. Its dead center. I even had my tuner/experienced engine builder look at it when we had my valve covers off a couple weeks ago. So, doing it this way and just adjusting for the difference in length via the base circle, will be just fine. Its a hydraulic lifter, not a solid. It dont have to be perfect...just close enough. I dont believe the Comp R lifters are as touchy or fragile as everyone else does.