Another lifter preload question ;)
Thread Starter
Instructor
Joined: Apr 2008
Posts: 245
Likes: 2
From: melbourne florida
Another lifter preload question ;)
The particulars;
Ls1 with ls6 ported and polished heads; heads just shaved .003 to make sure they were true.Running a 273 xer cam {xer lobes}with stock lifters,aftermarket chromoly pushrods; comp cams 7.4 length.Granted the stock pushrods are 7.385 on these motors,7.4 is what I decided to go with.Question; with these pushrods my preload is about .088. Is that to much for this setup? Concern is;with these xer lobes on this cam;there is lots of valvetrain noise.Runs great but not happy with the added noise. I also run a full set of headers so it does not help the noise issue I am sure.I set this up to run a little bigger on the preload thinking with more preload it might run quieter in advance but this may not be the case here.....Any ideas? Input? Thanx in advance. Note: You would think with a smaller base circle on these aftermarket cams that you would need a longer pushrod in general? Thoughts?
Ls1 with ls6 ported and polished heads; heads just shaved .003 to make sure they were true.Running a 273 xer cam {xer lobes}with stock lifters,aftermarket chromoly pushrods; comp cams 7.4 length.Granted the stock pushrods are 7.385 on these motors,7.4 is what I decided to go with.Question; with these pushrods my preload is about .088. Is that to much for this setup? Concern is;with these xer lobes on this cam;there is lots of valvetrain noise.Runs great but not happy with the added noise. I also run a full set of headers so it does not help the noise issue I am sure.I set this up to run a little bigger on the preload thinking with more preload it might run quieter in advance but this may not be the case here.....Any ideas? Input? Thanx in advance. Note: You would think with a smaller base circle on these aftermarket cams that you would need a longer pushrod in general? Thoughts?
Drifting
Joined: May 2007
Posts: 1,547
Likes: 210
From: Huntersville, NC
Are you sure the base circle is smaller? the preload on my cam was .080 but the machine shop compensated for both a small flycut to flatten the heads and to compensate for grinding the seats and valves (which also affects the "observed" preload) by grinding the valve tips. I ended up with stock length pushrods for an .080 preload, on every valve, and yes it is NOISY. I've run about 20 track days since, and maybe 5k street miles, and it is still holding together. If the shop is worth going to, they will know this and do this without telling you.
Regarding valvetrain noise, headers don't dampen sound like cast iron manifolds do, so you will hear a bunch of "disturbing" valve train noise with headers. Add to that the steep slope the valve train sees with a bigger cam and you have your noise. So you are comparing apples to oranges, sound-wise when you do a bunch of mods and add headers at the same time.
If the noise is bothering you, I'll trade you even for all your mod parts; my pile of stock parts, ls1 heads, exh manifolds, etc, for your mod parts and you pay all shipping!!!!! Then you will have the butter smooth quiet LS you had before.
Regarding valvetrain noise, headers don't dampen sound like cast iron manifolds do, so you will hear a bunch of "disturbing" valve train noise with headers. Add to that the steep slope the valve train sees with a bigger cam and you have your noise. So you are comparing apples to oranges, sound-wise when you do a bunch of mods and add headers at the same time.
If the noise is bothering you, I'll trade you even for all your mod parts; my pile of stock parts, ls1 heads, exh manifolds, etc, for your mod parts and you pay all shipping!!!!! Then you will have the butter smooth quiet LS you had before.
Drifting
Joined: Oct 2006
Posts: 1,724
Likes: 23
From: Minnesota
I'm running the (XR281HR) comp cam 228/230 .571/.573 112 w/comp cams OEM lifters. Initially, I went with ~.080" preload (7.4" pushrods (stock are 7.385" like you said). The noise drove me crazy. I switched out the pushrods for ~.040" preload. No real difference, the noise still drives me crazy. .088" might be a little much however, the noise isn't going away. I hate the valve train noise...sounds "loose".
I also put on YellaTerra rockers. No difference.
I've driven it hard for at least 10K miles, no problems.
Someone said this about the valve train noise: "Sounds like a tin tray full of silverware being carried by a person having a seizure."
I thought that was hilarious.
I also put on YellaTerra rockers. No difference.
I've driven it hard for at least 10K miles, no problems.
Someone said this about the valve train noise: "Sounds like a tin tray full of silverware being carried by a person having a seizure."
I thought that was hilarious.
Last edited by reactor2; Feb 16, 2015 at 11:59 PM.
yep that would be a good description for the noise my has with cam & headers.
Sort of lol.
