pushrod legnth and related questions
04-14-2010, 01:10 AM
#1
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pushrod legnth and related questions Stock heads/gaskets/lifters
XER273 cam 224/230 114LSA .581INT/.592EXH lift
Stock rockers - I plan on using the comp cams trunion upgrade kit
All the supporting stuff Patriot dual gold springs, LS2 timing chain, oil pump, etc.
This is for my weekend street/strip car
Long story short, the LS1 performance shop by my house swore that 7.400 pushrods would be what I would need(included in cam package) and if I needed to get a different size after I had everything apart and measured I could just swing by and exchange them. Now that I am ready to install, I come to find out the shop closed down and I am stuck with this set. Reading all the different posts on this site has me a little confused. I am ok with ordering new PRs (after measuring), but I want to confirm I have all my info straight ahead of time.
Will I need two different size PRs since my intake and exhaust are different or should the base circles be the same?
Is ~.050"-.060" preload correct for stock lifters? I know there are plenty of posts saying more/less is better, but what is the best general rule of thumb?
Will the trunion upgrade change my wipe pattern where I would have to shim my rockers? (I would assume that if I have the correct length PR I would not need to shim, but I am assuming and that is why I am asking)
Thanks in advance for any help
XER273 cam 224/230 114LSA .581INT/.592EXH lift
Stock rockers - I plan on using the comp cams trunion upgrade kit
All the supporting stuff Patriot dual gold springs, LS2 timing chain, oil pump, etc.
This is for my weekend street/strip car
Long story short, the LS1 performance shop by my house swore that 7.400 pushrods would be what I would need(included in cam package) and if I needed to get a different size after I had everything apart and measured I could just swing by and exchange them. Now that I am ready to install, I come to find out the shop closed down and I am stuck with this set. Reading all the different posts on this site has me a little confused. I am ok with ordering new PRs (after measuring), but I want to confirm I have all my info straight ahead of time.
Will I need two different size PRs since my intake and exhaust are different or should the base circles be the same?
Is ~.050"-.060" preload correct for stock lifters? I know there are plenty of posts saying more/less is better, but what is the best general rule of thumb?
Will the trunion upgrade change my wipe pattern where I would have to shim my rockers? (I would assume that if I have the correct length PR I would not need to shim, but I am assuming and that is why I am asking)
Thanks in advance for any help
04-14-2010, 07:23 AM
#2
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The only 100% sure way is to measure with a pushrod length checker after the cam is installed. That being said, with those XE-R lobes a 7.400 sounds right on. I just checked on my install, and my exhaust lobe (232 ex-r) needed just a tick longer than a 7.400, but I dropped down to that common size. Since your lobes are both xe-r I would say you would need the same pushrod. Cams with different lobes (Lsk/xer, xfi/xer, etc) more commonly require a different length for intake and exhaust. The typical range of pre-load is .050-.080", but that can vary depending on who you ask. I also used the Comp trunion upgrade, and it hasn't changed my wipe pattern.
04-14-2010, 08:43 AM
#3
The only 100% sure way is to measure with a pushrod length checker after the cam is installed. That being said, with those XE-R lobes a 7.400 sounds right on. I just checked on my install, and my exhaust lobe (232 ex-r) needed just a tick longer than a 7.400, but I dropped down to that common size. Since your lobes are both xe-r I would say you would need the same pushrod. Cams with different lobes (Lsk/xer, xfi/xer, etc) more commonly require a different length for intake and exhaust. The typical range of pre-load is .050-.080", but that can vary depending on who you ask. I also used the Comp trunion upgrade, and it hasn't changed my wipe pattern.
04-14-2010, 12:22 PM
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Thanks guys. I am definitely measuring, just wanted to make sure I was measuring correctly and had my facts straight for preload. Hopefully after this weekend if all goes well I'll be driving like Ricky Bobby
