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Jimmypooh

Valve help needed

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Jimmypooh

This pertains to a big block 454 in my 67 Camaro. It started popping/back firing. I thought it was the carb so I had it rebuilt. After he rebuilt it, the popping didn't stop, so he tried adjusting the valves. He said he couldn't get the number 6 exhaust lifter adjusted. He thought it might be a lifter/cam problem. I felt like taking it from there. If I'm going to own a classic, I may as well learn to repair it.

So I brought the car home and started tearing into it. I find that the number 6 is loose but I can adjust it down. However there seem to be a lot more threads showing than the rest. Also it looks like the spring is seated in a different position than the rest of the springs. Do you think there is a bent valve? Do I need to reseat the spring? Do you think I should pull the cam/lifters and have a look? Below are some pictures of the issue.

Number 6 problem on the bottom right, number 8 on the bottom left. Notice that the base of the number 6 spring is at the bottom of the opening while the number 8 spring is at the top.

IMG_20130125_224201_zpse8b3638c.jpg

You can see in this picture that the number 6 (bottom second to left)is leaning out more than the others. You can also see the larger amount of threads needed to get it tight.

IMG_20130125_224959_zps146b1f9b.jpg

Thanks for the help!

Jim

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G-Mack

check the installed height of the valve. If it is consistent them it is not a hung valve... then you move to lifter assuming hydraulic lifter... then it could be a camshaft... failure of the case hardening of the camshaft can wear out the lobe very quickly... pull the coil wire and turn the motor over again assuming hydraulic lifters you can build enough oil pressure to see what is happening

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Jimmypooh

Thanks for the info. I will check the installed height and see if they are the same.

I should add a few more things....

It doesn't pop when cold, only when up to temp.

Not sure if this is normal, but with my breaker bar (2 foot) the engine is very hard to turn over by hand. It takes about 50 lbs of pressure to get it to move.

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scfdfireman

The motor will be hard to turn with the spark plugs in especially if the compression is on the higher side. Take the plugs out or use a starter switch to turn it over. I was wondering why the progression from the carb to the valves? There's quite a few electrical components that may be the hidden issue (cap, rotor, wires, points, coil, etc). If the cam lobe has gone flat on that cylinder you won't see the lifter rise (or rise as high) as the motor turns over. Before you start fooling with the adjusting nuts find out if you have solid or hydraulic lifters...

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CliffB

That does sound somewhat like a bent valve. As suggested, check the installed height - if it's short then you've got a valve that isn't fully seating. The valve stem should move smoothly and freely, but without excessive side to side play.

Sounds like you have hydraulic lifters....sometimes those get sticky and bind. You can take them out and clean them all and reinstall and see if that makes a difference.

Good luck!

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Jimmypooh

I was wondering why the progression from the carb to the valves? There's quite a few electrical components that may be the hidden issue (cap, rotor, wires, points, coil, etc). If the cam lobe has gone flat on that cylinder you won't see the lifter rise (or rise as high) as the motor turns over. Before you start fooling with the adjusting nuts find out if you have solid or hydraulic lifters...

Carb to valves---Because I'm just learning. Mechanic pointed me to valves. I replaced the distributor about 2000 miles ago (the weights in the old one blew up), but kept the coil, cap, and wires. I should probably replace those since I don't know when they were originally put in there.

I think I have hydraulic lifters; how can I tell? Take the intake off and pull one? I'm due for some maintenance and am eager to learn, so I don't mind pulling stuff apart even if it's to check it out and maybe clean it.

If I measure cam lift with hydraulic lifters, do I have to do something special since they will compress?

I also have timing gears instead of a chain which I don't really care for. If I end up replacing the cam, I will swap out to a chain.

One thing I wasn't expecting was to see some jagged looking holes in the heads that you can see down to the lifters. See Below:

IMG_20130125_194241_zps1e6f2cae.jpg

Edited by Jimmypooh

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Steve B.

Yes, make certain its not an electrical issue first. Do a compression test also. What led up to this issue?

Did you over rev it by a mis shift to like 9000 rpms? Did the engine overheat?

Keep us posted,

Steve B.

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greg2vlx

I'm not an expert, but have built a couple of engines. Do you have the cam shaft/engine in the right postion to tighten that particular valve/rocker arm? If the engine is not in the correct position you can easliy overtighten the rocker arm nut. My point is you can't tighten/adjust all of the valves from TDC.

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Jimmypooh

Yes, make certain its not an electrical issue first. Do a compression test also. What led up to this issue?

Did you over rev it by a mis shift to like 9000 rpms? Did the engine overheat?

Keep us posted,

Steve B.

Didn't miss a shift. Never overheated. The car sits a lot so it might be that. I just started it one day after it sitting for a while and it was popping. Maybe I'll do a compression test tomorrow as well as check the installed valve height.

I'm not an expert, but have built a couple of engines. Do you have the cam shaft/engine in the right postion to tighten that particular valve/rocker arm? If the engine is not in the correct position you can easliy overtighten the rocker arm nut. My point is you can't tighten/adjust all of the valves from TDC.

Thanks. I have been reading a lot before I do anything. I know I can't adjust everything from TDC. I have most of the day tomorrow to mess with it so I will start checking a few things and post back up tomorrow night.

Thanks for the help everyone.

Jim

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Jimmypooh

I spent the day tearing apart the engine. I found a worn lobe and lifter. I will be ordering a new cam and lifters. I will also be replacing my timing gear driver with a chain drive. I don't care for the noise of the gear drive. If anyone wants my old one, it's only got a few thousand on it.

My question now is, did something cause this to wear, or was it just a problem with the cam/lifter? Is it going to happen again? Should I pull that spring and check the valve? Does anyone have any recommendations of cam to put in it? It's a 454 in a 67 Camaro used for street. I don't know what the current cam is, but included pictures below. I will try figuring out the current cam by the stamp tomorrow.

Engine Torn Down

IMG_20130127_185051_zps56256f14.jpg

Worn Lobe

IMG_20130127_193848_zpsa76c559f.jpg

Worn Lifter

IMG_20130127_193811_zpsf8629e06.jpg

Cam Stamp

IMG_20130127_195448_zps8a9a6ea6.jpg

Edited by Jimmypooh

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Jimmypooh

I wonder if it's worth taking the heads off and pulling them apart to check the valves/springs. Any thoughts on what could have caused this cam/lifter failure?

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scfdfireman

Typically a worn cam lobe won't effect the valve train, but since you're so far into it it may be a good piece of mind. I restored a 66 corvette and used a "Competition" brand cam since they offered an OEM style solid lifter cam. Since your car isn't stock I'd go with a hydraulic cam and lifters since it will be much easier. Stay with a name brand or even GM performance parts. Also, be sure to change your oil and filter and after you run it for a bit change it again to try and flush the small metal fines out. The cam may have failed due to a bad casting or a bad lifter or improper adjustment or lubrication... The holes in the head are just ruff casting holes and are normal...

Edited by scfdfireman

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Tims

You are pretty far into this engine now. Any thoughts of doing a full rebuild? That worn metal from the cam and lifter is more than likely sitting at the bottom of your oil pan. Totally understand if you are on a specific budget, just something to think about. At minimum, consider doing a leakdown test on each cylinder to determine ring and valve seal. Noticed that you had roller valve train so I am assuming that you have some kind of performance cam. When considering a replacement, take a look at the packages (cam, head, intake, carb) from the big name brands. They do a good job of matching thing up to optimize performance. Noticed you have oval port heads; if it were me, I would try and find a set of square port heads or similar aftermarket ones and match them up as referenced above. The boost in performance will be significant and make the teardown worth it. :chevy:

Let us know how it goes.

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sprintdriver47

Don't know about taking the heads off to check the valves. Get a cylinder leak down tester and check each one. If you have a bad ring or bad valve seat it will show up with that test.

Also with a bad lifter/cam combo like that I would definately be checking the springs with a spring tester. Or most likely look at replacing them anyway because they may not end up being the correct seat pressure for the new cam and lifters.

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vette-ski

Again, another non-expert weighing in.....I would do some investigation into what caused that. The wear seems excessive, and to only be on one lobe/lifter points to a lack of lubrication in that spot in my opinion. Make sure the oil passage is clear....I believe it is in the lifter bore. And I think once the oil fills the lifter it goes up the push rod like a straw to the rocker arm. Any blockage will stop oil flow. If you just replace and put it back together, my gut feel is yes, you'll be doing this again. Unless it was just a bad lifter or poor lifter-to-bore clearance. Unfortunately, if there is a blockage in the block somewhere, the best solution is to have it tanked (IE, pull out and tear down completely).

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Steve B.

Wow. I've never seen a cam lobe worn like that, or a lifter like that too. The valve and spring are now suspect for sure. But a compression/ leakdown should find if there is an issue.

I'm wondering if it was an oiling problem. Clogged pushrod or something. How did the spark plug on that cylinder look? How does the exhaust manifold look at that cylinder?

Overall oil pressure was good?

Good luck,

Steve B.

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Jimmypooh

I will perform a leak down test this evening. I think I was getting oil in a few of the cylinders but that could have been from the intake gasket. It' looked pretty shotty when I pulled it off. A couple of the plugs cam out with oil on them and all of them had a lot of carbon on them.

I don't really want to get into spending a ton for this repair. I might upgrade to a roller cam instead of flat, but that's about it on the expense upgrade area. The rest of the lobes were fine so I doubt the springs caused any problems.

I think I will pull the heads and check the condition of the valves and the spring load. I'll learn a little more and have the piece of mind.

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Sixball

Once a cam and lifter start to go they go fast. I can not tell you what started the issues but cam's are hardened but not the entire lobe. You can pull the spring and check it without puling the head. I will bet you have a inner spring also. A leak down will let you know if the valve and seat are good. I would run it on all cylinders to see if you have other problems. If you change your cam you may need to change springs and spring set up. You will need new lifters with the new cam. If you are not building to a point that you receive benefits from a roller cam I would not put rollers in. If you make changes you need to sit down and look at what you want to do before you start. The only way to get everything out and as cheep as you can is to know what you want to do before you start.

Your playing with something that can make owning a boat look like a drop in a bucket! :whistle: I have some background in this!

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Jimmypooh

Once a cam and lifter start to go they go fast. I can not tell you what started the issues but cam's are hardened but not the entire lobe. You can pull the spring and check it without puling the head. I will bet you have a inner spring also. A leak down will let you know if the valve and seat are good. I would run it on all cylinders to see if you have other problems. If you change your cam you may need to change springs and spring set up. You will need new lifters with the new cam. If you are not building to a point that you receive benefits from a roller cam I would not put rollers in. If you make changes you need to sit down and look at what you want to do before you start. The only way to get everything out and as cheep as you can is to know what you want to do before you start.

Your playing with something that can make owning a boat look like a drop in a bucket! :whistle: I have some background in this!

Thanks for the info. That's good advice...I plan on doing lots of research before starting the rebuild process or even buying any parts. I was thinking about checking the current spring pressure using something like this. That way I may be able to see what cams would work with my current springs. I tried looking up the stamped numbers on the existing cam and can't find what it is. I think I might also run the oil pump with a primer to make sure nothing is clogged near the failed lifter.

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Sixball

We used the same valve spring tool all the time when we ran our drag car. For a quick check its a good tool.

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Jimmypooh

So a little update on my engine project. I decided to pull the heads and do a valve job while I'm at it. I will also be testing the spring pressure to see if I can use them on the new cam. When I pulled off the head I noticed that the head gasket looked like it was too big for the cylinders (see picture below). You can see the carbon between where the gasket sat and the edge of the cylinder. Does this look right to anyone?

I also wanted to pull the pan and oil pump to clean it out and put in a new gasket. I found that I have to pull the engine in order to pull the pan. So be it! I ordered an engine crane and engine stand. While the engine is out I will be steaming the engine compartment and installing a much needed suspension kit.

IMG_20130212_182557_zpse303ece3.jpg

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Lance B. Johnson

I have seen a few HGs that do this. Never had a problem with one as long as the water passages all match.

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Falko

Looks normal to me.

I just read this thread. Your cam and lifter probably failed due to being misadjusted from the start. And as stated, once you burn off the hardened area, it goes down hill quick.

Edited by Falko

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Steve B.

The one modification I think I'd make since you've gone this far, is to go with roller bearing type rocker arms. I wouldn't change the ratio, but there are affordable sets out there that reduce valve train friction greatly.

Steve B.

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Lance B. Johnson

Naw, the flat cam is due to a couple things. 1. It's a Chevy and flat cams are very common. 2. High lift long duration cams make matters even worse.

Valve adjustment COULD have been an issue but I doubt it in this case.

As far as springs are concerned I would buy the recommended springs for the cam. So buy cam, springs, lifters all from same company and go with their recomendation. You can measure with a rimac but I wouldn't bother. I'd just buy recommended springs.

Edited by Ruffdog

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