Rocker/push Rod Issue
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Instructor
Joined: Aug 2013
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From: Johnston Rhode Island
Rocker/push Rod Issue
Hey guys. Been a while, but I value the collective knowledge here, so this is my thought process.
Took the 71 out for a bit today. Ran great like always. Leaving my laundromat I started hearing popping coming from up front/under hood. No other noise than the popping. Minimal popping upon start up and somewhat rough idle. Any pedal movement increases the popping. Pulled right over etc. Had it flat bedded home.
My thought is possibly I popped a rod....or the rockers are loose...or worse yet a cam problem. Didn't have a chance to look yet, but when I do I will take the valve covers off and crank to make sure everything is moving. Prior to that I might fire it up under cover of darkness and see if I cooked a wire or something easy. I am just brainstorming at this point so I have a direction. I have a small block 350 bored .6 with roller rockers.
Any suggestions would be appreciated and I will update as I go along. Thanks for reading.
Took the 71 out for a bit today. Ran great like always. Leaving my laundromat I started hearing popping coming from up front/under hood. No other noise than the popping. Minimal popping upon start up and somewhat rough idle. Any pedal movement increases the popping. Pulled right over etc. Had it flat bedded home.
My thought is possibly I popped a rod....or the rockers are loose...or worse yet a cam problem. Didn't have a chance to look yet, but when I do I will take the valve covers off and crank to make sure everything is moving. Prior to that I might fire it up under cover of darkness and see if I cooked a wire or something easy. I am just brainstorming at this point so I have a direction. I have a small block 350 bored .6 with roller rockers.
Any suggestions would be appreciated and I will update as I go along. Thanks for reading.
Le Mans Master
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Hey guys. Been a while, but I value the collective knowledge here, so this is my thought process.
Took the 71 out for a bit today. Ran great like always. Leaving my laundromat I started hearing popping coming from up front/under hood. No other noise than the popping. Minimal popping upon start up and somewhat rough idle. Any pedal movement increases the popping. Pulled right over etc. Had it flat bedded home.
My thought is possibly I popped a rod....or the rockers are loose...or worse yet a cam problem. Didn't have a chance to look yet, but when I do I will take the valve covers off and crank to make sure everything is moving. Prior to that I might fire it up under cover of darkness and see if I cooked a wire or something easy. I am just brainstorming at this point so I have a direction. I have a small block 350 bored .6 with roller rockers.
Any suggestions would be appreciated and I will update as I go along. Thanks for reading.
Took the 71 out for a bit today. Ran great like always. Leaving my laundromat I started hearing popping coming from up front/under hood. No other noise than the popping. Minimal popping upon start up and somewhat rough idle. Any pedal movement increases the popping. Pulled right over etc. Had it flat bedded home.
My thought is possibly I popped a rod....or the rockers are loose...or worse yet a cam problem. Didn't have a chance to look yet, but when I do I will take the valve covers off and crank to make sure everything is moving. Prior to that I might fire it up under cover of darkness and see if I cooked a wire or something easy. I am just brainstorming at this point so I have a direction. I have a small block 350 bored .6 with roller rockers.
Any suggestions would be appreciated and I will update as I go along. Thanks for reading.
All the push rods should slowly spin if the cam taper is intact.(It's the first thing to go)
Look for broken valve springs/loose rockers
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Sounds like a dead exhaust on one cylinder that's not opening. Rocker, stud, pushrod hopefully. Easy fixes....after that we look at cam/lifters.
JIM
JIM
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From: Johnston Rhode Island
Thanks guys. We're on the same page with the rods....hopefully. I was being very optimistic with wires, but I know that won't be the case.
I will try to get in there tomm. I get such anxiety when something is broken/not working right. I will report back.
I will try to get in there tomm. I get such anxiety when something is broken/not working right. I will report back.
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I'm assuming it's a steady/rythmic popping that increases with RPM?
JIM
JIM
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From: Johnston Rhode Island
427hotrod....you are correct.
I opened up the cover on the passengers side. The rocker was just laying in there. The stud is snapped with the adjustment nut on it. I hope I can get the rest of the stud out without pulling everything apart. They are threaded studs, but I can't remember if I used Loctite. It was a long time ago. I can't really see anything on the sides.
I opened up the cover on the passengers side. The rocker was just laying in there. The stud is snapped with the adjustment nut on it. I hope I can get the rest of the stud out without pulling everything apart. They are threaded studs, but I can't remember if I used Loctite. It was a long time ago. I can't really see anything on the sides.
Last edited by Hpozzuoli; Sep 28, 2015 at 11:12 AM.
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From: Johnston Rhode Island
I was able to get my threaded stud out very easily. I didn't use Loctite apparently. I was also able to extract the snapped bolt out of my adjustment girdle. Only thing I need is a new stud and adjust the valves. Might as well hit them all. Good thing it's going to rain all week here. I should be on the road next weekend.
Melting Slicks
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From: Michigan
I use permatex thread sealer on my heads for rocker studs, some heads intake studs go right into the runner and you'll use oil if you don't seal it. I also always use arp rocker studs, compared to cheap studs the arp have a flat top that helps hold lash. Check your pushrod 
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Good news is it's an easy fix.
But you might want to look closely at the rocker geometry and specifically pushrod length. I can't really see the pattern on the valve, but those rockers are riding way high on the stud. That's causing you to not have a lot of thread engagement in the adjuster nut. "IF" the pushrod length is correct, you might look into some longer studs. If correct the rocker should pivot down in the shank area...not up on the threads.
If the heads have longer than stock valves, valve sunk during a valvejob, or have been milled, or block milled etc...it all adds up.
JIM
But you might want to look closely at the rocker geometry and specifically pushrod length. I can't really see the pattern on the valve, but those rockers are riding way high on the stud. That's causing you to not have a lot of thread engagement in the adjuster nut. "IF" the pushrod length is correct, you might look into some longer studs. If correct the rocker should pivot down in the shank area...not up on the threads.
If the heads have longer than stock valves, valve sunk during a valvejob, or have been milled, or block milled etc...it all adds up.
JIM
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Joined: Aug 2013
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From: Johnston Rhode Island
Good news is it's an easy fix.
But you might want to look closely at the rocker geometry and specifically pushrod length. I can't really see the pattern on the valve, but those rockers are riding way high on the stud. That's causing you to not have a lot of thread engagement in the adjuster nut. "IF" the pushrod length is correct, you might look into some longer studs. If correct the rocker should pivot down in the shank area...not up on the threads.
If the heads have longer than stock valves, valve sunk during a valvejob, or have been milled, or block milled etc...it all adds up.
JIM
But you might want to look closely at the rocker geometry and specifically pushrod length. I can't really see the pattern on the valve, but those rockers are riding way high on the stud. That's causing you to not have a lot of thread engagement in the adjuster nut. "IF" the pushrod length is correct, you might look into some longer studs. If correct the rocker should pivot down in the shank area...not up on the threads.
If the heads have longer than stock valves, valve sunk during a valvejob, or have been milled, or block milled etc...it all adds up.
JIM
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Ideally you want as much thread in the nut as possible. The allen screw locks should be close to flush with the top.
Here's a good video that will show you what to look for.
https://www.youtube.com/watch?v=o5is...ature=youtu.be
JIM
Here's a good video that will show you what to look for.
https://www.youtube.com/watch?v=o5is...ature=youtu.be
JIM
Drifting
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Good news is it's an easy fix.
But you might want to look closely at the rocker geometry and specifically pushrod length. I can't really see the pattern on the valve, but those rockers are riding way high on the stud. That's causing you to not have a lot of thread engagement in the adjuster nut. "IF" the pushrod length is correct, you might look into some longer studs. If correct the rocker should pivot down in the shank area...not up on the threads.
If the heads have longer than stock valves, valve sunk during a valvejob, or have been milled, or block milled etc...it all adds up.
JIM
But you might want to look closely at the rocker geometry and specifically pushrod length. I can't really see the pattern on the valve, but those rockers are riding way high on the stud. That's causing you to not have a lot of thread engagement in the adjuster nut. "IF" the pushrod length is correct, you might look into some longer studs. If correct the rocker should pivot down in the shank area...not up on the threads.
If the heads have longer than stock valves, valve sunk during a valvejob, or have been milled, or block milled etc...it all adds up.
JIM
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From: Johnston Rhode Island
Thank you guys for the advice. I will look at the video later tonite. I have it bookmarked. I built this car 20years ago with my dad. I was 18 at the time. I didn't make all the decisions on what performance parts to use, but I did all the assembly etc. My family owned an Arco/Sunoco gas/repair station until 2 years ago when we sold it. I deferred to dad for what parts. Now this doesn't mean we picked the right stuff or did things the best possible way. We didn't have internet then either. So I value the input here.
Here's a shot of the rod showing the length.
Here's a shot of the rod showing the length.
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The main idea is to get the pivot point on the rocker in the right place on the studs as well as positioning the rocker geometry correctly.
The issue isn't the nut coming loose from lack of engagement like you would concern yourself with on something you were actually tightening....it's all that motion going on at the top of the stud in the thread area. Grabbing the top 3/8" of an inch will eventually snap it off just like this one did if the cam has any real motion to it at all.
JIM
The issue isn't the nut coming loose from lack of engagement like you would concern yourself with on something you were actually tightening....it's all that motion going on at the top of the stud in the thread area. Grabbing the top 3/8" of an inch will eventually snap it off just like this one did if the cam has any real motion to it at all.
JIM
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Can you wipe off the tip of the valve and get a good shot of the wear mark on the tip?
JIM
JIM
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Figured I would give a little update. I put everything back together, started it, and heard a horrible rocker slapping noise. Pulled off the front two rockers on the passengers side. Both had chunks taken out of the back. I pulled both rods, one was good and the other was bent. I ordered 2 new rods and 2 new roller rockers. Fired her up and she purrs. Even with the valve covers off the rockers are silent. Sadly I haven't driven it due to weather and time, but I am happy it's back together.
Thank to all who helped with some great insight.
Thank to all who helped with some great insight.
Last edited by Hpozzuoli; Dec 16, 2015 at 05:48 PM.