Valve to guide clearance
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Teching In
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From: Finland
Valve to guide clearance I haven't found service limit for valve to guide clearance in LS1. I measured valves and those were within 0.039" within the valve length.
I did also the wiggle test since I don't have such a small micrometer to measure the guide itself. It shows 0.0045 in tightest valve and 0.005 in loosest one.
I didn't have valve springs installed while I did this test.
These valves have been installed 10 years ago but the car has been driven only ~30 k since. The heads have 100 k on them.
Is it time for a stem job or should I leave it like this?
I did also the wiggle test since I don't have such a small micrometer to measure the guide itself. It shows 0.0045 in tightest valve and 0.005 in loosest one.
I didn't have valve springs installed while I did this test.
These valves have been installed 10 years ago but the car has been driven only ~30 k since. The heads have 100 k on them.
Is it time for a stem job or should I leave it like this?
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Without knowing exactly how or what you wiggled, it's hard to say for sure if that's alot or a little. Butt as consistent as they are, especially if it's about the same in all directions, it's probably just fine. Guides usually wear to one direction or another according to the side loads from the rockers, and differently on different valves, so if you don't have that, then the amount of wear is minimal.
Thread Starter
Teching In
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From: Finland
Thanks for the reply.
I put a magnetic leg to my steel table and clamped the head to that same table. I put a dial gauge against the valve top and moved it sideways from intake side to exhaust side. I didn't test the other direction but that's a good hint. I'll do that too and if I get such big numbers, then at least the guide hasn't an oval shape.
I put a magnetic leg to my steel table and clamped the head to that same table. I put a dial gauge against the valve top and moved it sideways from intake side to exhaust side. I didn't test the other direction but that's a good hint. I'll do that too and if I get such big numbers, then at least the guide hasn't an oval shape.
Wiggle test is a joke. It’s meaningless. Nothing accurate about it at all.
I set my valve to guide clearance up at .0015…intake and exhaust. Service limit is like .0037
You need to invest in the correct dial bore tool to measure guide ID and a nice mic to measure your stems. The tooling is expensive. A shop will charge you a fraction of this to accurately tell you where your at. Fwiw the sintered iron guides wear very slowly. I’ve seen 300k mile heads with such little wear, that I don’t worry about the guides….they last a long long time. Bronze is a very different story.
I set my valve to guide clearance up at .0015…intake and exhaust. Service limit is like .0037
You need to invest in the correct dial bore tool to measure guide ID and a nice mic to measure your stems. The tooling is expensive. A shop will charge you a fraction of this to accurately tell you where your at. Fwiw the sintered iron guides wear very slowly. I’ve seen 300k mile heads with such little wear, that I don’t worry about the guides….they last a long long time. Bronze is a very different story.
TECH Senior Member
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From: Central Cal.
Scott-knowing what you just said about bronze guide wear, what is their advantage?
Plus you need roller tip rockers to avoid much of that wear,
AFR requires them for their heads w/ bronze guides
Plus you need roller tip rockers to avoid much of that wear,
AFR requires them for their heads w/ bronze guides
Wiggle test on a valve with the valve spring installed will tell you that there's a problem. Ask me how I know.
Manganese guides are a softer metal and wear before wearing out the valve stem.
Manganese guides are a softer metal and wear before wearing out the valve stem.
Thread Starter
Teching In
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From: Finland
Today I tested one exhaust and one intake valve again. Sideways the intake valve had half of the travel against wiggling from intake to exhaust side. The exhaust valve had same big travel in both ways.
I'll get my hands on a small bore gauge and measure the bore. I'll let you know.
I'll get my hands on a small bore gauge and measure the bore. I'll let you know.
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Aftermarket heads with bronze guides, such as AFR, are typically going to be used with roller rockers as a general rule of thumb, for performance. The argument for the LS steel rocker being superior to roller rockers due to weight savings is not what I’m trying to start here. Ask any builder who builds high rpm LS builds about that topic. Roller rockers reduce guide wear and oil temps, therefor making the move to bronze guides a good choice unless your looking for a 250k mile build.
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Verdad Gallardo TECH Senior Member
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From: Central Cal.
Bronze has a natural lubricity, which is important for making power. When building an engine for max power, reliability isn’t on the chalkboard. Bronze guides also help cool the valve stem through heat transfer. The only time the valve is cooling is when it’s on the seat, which isn’t for very long. The bronze material transfers heat quicker into the casting, thus helping cool the valves. It’s not exceptional but every bit helps when valve temps are high.
Aftermarket heads with bronze guides, such as AFR, are typically going to be used with roller rockers as a general rule of thumb, for performance. The argument for the LS steel rocker being superior to roller rockers due to weight savings is not what I’m trying to start here. Ask any builder who builds high rpm LS builds about that topic. Roller rockers reduce guide wear and oil temps, therefor making the move to bronze guides a good choice unless your looking for a 250k mile build.
Aftermarket heads with bronze guides, such as AFR, are typically going to be used with roller rockers as a general rule of thumb, for performance. The argument for the LS steel rocker being superior to roller rockers due to weight savings is not what I’m trying to start here. Ask any builder who builds high rpm LS builds about that topic. Roller rockers reduce guide wear and oil temps, therefor making the move to bronze guides a good choice unless your looking for a 250k mile build.
Thank you!
Thread Starter
Teching In
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From: Finland
Small update on this. I haven't found a shop nearby which would have a small enough bore gauge.
I tested the theory of wiggle test with an old school approach: I draw these parts as they are measured, into a 2D CAD software.
Then, assuming that valve guide is worn in hourglass-shape, I pushed the valve the measured amount from the top sideways. So that center point in the guide will be the pivot point.
Even if the end of the valve moves 0.005", the clearance between valve and guide is 0.002"
I know this is just theoretical but I cant see why wouldn't this relate to real life as well. Anyway, I'll still measure the guides but I wouldnt be surprised if they are within service limits. My trust on wiggle test is now on test
I tested the theory of wiggle test with an old school approach: I draw these parts as they are measured, into a 2D CAD software.
Then, assuming that valve guide is worn in hourglass-shape, I pushed the valve the measured amount from the top sideways. So that center point in the guide will be the pivot point.
Even if the end of the valve moves 0.005", the clearance between valve and guide is 0.002"
I know this is just theoretical but I cant see why wouldn't this relate to real life as well. Anyway, I'll still measure the guides but I wouldnt be surprised if they are within service limits. My trust on wiggle test is now on test
Movement should be minimal when performing a wiggle test of a valve with valve spring installed. It should be stiff. It's when the valve moves excessively as in up and down indicating a worn valve guide. I witnessed this on a set of TSP PRC LS7 heads I purchased that once had Manley ti valves but the guy I let work on them ended up stealing those valves and installing LS3 hollow stems in there and it didn't take too long to wear out the manganese guides. Valvetrain noise became excessive and after pulling a valve cover and performing a simple wiggle test I quickly found out that all the intake guides were shot. It wasn't until I pulled the heads and did my own investigation that I learned that my valves were stolen..Many years ago but I'd still like to get back at that guy for the $1,500 he stole from me.
What comes around goes around!
What comes around goes around!
Thread Starter
Teching In
Joined: Jun 2013
Posts: 18
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From: Finland