Hot Rod Forum banner

dead cylinder? Confused and about to lose my mind

6K views 25 replies 8 participants last post by  bowtie76 
#1 · (Edited)
i got a 1971 camaro with a stock SBC 350. I have a edlebrock intake with a 600cfm holley carb. I installed a Accel HEI dist a few months ago. car was running great. I was driving from NY to Virgina and the car started backfiring on the way down. When I pulled off the road I found that two of my spark plug wires burned up. I went ahead and replaced all the wires. tooki it back out on the road and it was still doing the same thing. I went ahead and pulled the plugs. Ifound a couple were fouled out in the same cylinders that the wires were burned. So I replaced all 8 plugs jsut to cover everything. I got back on teh road and it still did the same thing. Now confused I pulled the cap and rotor. All the points seemed like that had been burned up. i went ahead and cleaned them still didnt change anything. So I decided to get a new cap and rotor. After i installed it nothing changed. I talked to a fellow mechanic and he mentioned the coil. I didnt have any way to test the coil so having the extra money and no were near home I bought a new coil adn put it on. Still nothing.
finally after 8 weeks of being gone I was able to get home. i contacted accell and talked to them. the guy said it sounded like the control module was bad. I couldnt find the receipt he wanted so i took the distributor back to were I bought it and they warrantied it out. i dropped the new one in and still havent had any luck. Now being beyond mad I took it into a shop. They couldnt look into it for long. he did a couple quick checks on it and found that the #6 Cyl was 200 deg cooler then the other 7. He pulled the plug adn it was getting spark but it still looked brand new. he mentioned a possible sucked in intake gasket. I did bring it to work and replaced the valve cover gaskets and turned it over by hand. Saw all the valves moving. All though I did find the intake valve on the #4 cylinder was loose. you caould pick it up by hand and turn it around. I tightned it back down. But I dont know if I should pull the heads and intake off and replace the gaskets. I know at some point someone is going to tell me I am retarded for putting all the money into it replacing everything when i could have spent the money to take it to a shop to diagnose the issue. but I am past that point and I am at a point were I am ready to drive it over a cliff and leave it be. This is my everyday driver at this point. Can anyone help me out?
 
See less See more
#4 ·
Run a compression test and leak-down test. Make sure none of the rocker nuts are over tightened or it will hold the valve open. Turn the engine over a few times and make sure all the rockers move the same amount. Make sure all the plugs are sparking and at the right time. Let us know what you find. :thumbup:
 
#5 ·
ok, so I decided on my day off to tear it down some. didnt have time to go to indepth on it.
I went ahead and removed the intake manifold. Needless to say that the gasket was beyond tore up. But it went down hill from there. I didnt have a compression gauge to check the cylinders. But I had a buddy turn it over by hand. I did find that the #6 was not sealing at all. both valves were moving good. however when it go into the compression stroke I could see bubbles leaking from the intake valve and you can hear a hissing noise coming from it. I also noticed that the two valves had a different amount of travel when they closed. the intake valave didnt seem toclose enough like the exhaust valve did. Also when i removed the intake the exhaust port that connects the #4 and #3 exhaust valves was clogged. i had to chisel it out with a screwdriver. I cleaned everything up and also noticed that on passenger side head there were large gouges taken out in the head by the #2 and #4 Intake valves. I did check the plugs and the amount of spark and the color of them. They all spark the same and all but the #6 plug are a slight brown color. the #6 is still white. I am sure at this point I need to replace he heads. I am sure I could probably get away with just getting a valve job. but seeing the knicks in the head concerned me. I replaced all the intake gaskets. I also reset the timing. it was also off some. it runs better than it did but is still popping when it is under a load. if I am gentle with it she seems to do ok but the slightest hill I had to climb you can feel the loss in power and she starts popping. Is there anything I could possibly do with the valves to fix them without replacing the heads or am I at the point I am lucky it is still running?
 
#9 ·
I know I need to do a compression check. I know it is easy and fast just a matter of getting the time off to get it done. I was expecting about that much for the parts. I guess i am going to have to force work into giving me the time off to get the compression checked. i know it was done years ago. i had the intake and rear main gaskets replaced. He said he ran the compression and all were up to 120 psi but the #8 cyl was running 90. Now it seems it has moved into other cylinders like a disease HAHA. imagine that!! Thanks for the info
 
#11 ·
Ok well at this point I wont lie. You just spoke spanish to me. LOL I uno dos tres and that is it. I got the basics and can take something apart and get it back together like it was new. IF I know what I am looking for and doing. As for what i have done to i. I have dealt with all that before. but i have never really messed with the rockers other than tightening the one up that was about to fall off.
 
#12 ·
bowtie76 said:
Ok well at this point I wont lie. You just spoke spanish to me. LOL I uno dos tres and that is it. I got the basics and can take something apart and get it back together like it was new. IF I know what I am looking for and doing. As for what i have done to i. I have dealt with all that before. but i have never really messed with the rockers other than tightening the one up that was about to fall off.
Try this link from our knowledge base
 
#14 ·
Thanks overdriv. i am going to try that this weekend. doesnt look tough at all. Most of everything I have learned so far has been hands on. So again thanks. I am hoping that helps some. Only because I dont want to start learning how to install a new cam yet haha. I was hoping to do that when I find another engine. i have always wanted to build one from the ground up to put in my camaro. It is looking like I might be doing that sooner than later.
but i do have anotehr question. I have read a few places about the popping also being linked to a lean condition or retarded timing. i know the timing isnt retarded. But as for running lean. Well that I am unsure of. I know it has plenty of fuel flow. Is there a way to find out if it is running too lean?
 
#15 ·
Ok so here is a question i was pondering today at work. I know I had been told a possible bad lobe on my cam could cause the issue I have with my car. however, when I had the intake off and watching the valves open and close. They all did just that. the intake fully opened and just don't seem to close. So that would rule out a bad cam right? second It was mentioned to adjust the valve and make sure they are zero backlash. I read up on it. looks simple. But the question I have at this point. If i never had a issue up until recently, wouldn't the rocker be loose when the valve is closed? Not holding it open. A nut doesn't tighten itself down on a spring loaded valve. I am going to buy a compression gauge tomorrow morning and test the compression. but I wanted to get someones opinion on it before I start messing with the valves. There is one I know for a fact came loose and that was on the #4 cylinder intake valve. i just tightened it down to stop the slapping it was doing. So that I will adjust properly. but can someone answer the other questions I have please.
 
#17 ·
bad gas (old gas) can stick valves open. Especially on the intake valves.

Old gas gets sticky and stinky with age and gums up the valve guides and sticks the valves.

if the valves are sticking in one place, then that also tends to eat cams due to the extreme force on the lifter that is trying to move the stuck valve.

I have seen valve seats fall out which get trapped and hold the valve open.

but a cam lobe only can push, not pull (opposite of a rope).

compression test will show the dead cylinders. autozone rents tools for free (they give you the money back when you return the tool)
 
#18 · (Edited)
I suggested you adjust the pre-load on the lifters because it sounded to me you either didn't do it right or might have messed up the adjustment by just tightening one or more down.

Now you are saying an intake valve is not closing?? That is a serious problem.

You are a bit confusing in your posts.

Step back, take a deep breath. Do the following if you want us to help you. Do not skip any step.

1. Adjust the lifter pre-load to 1/2 turn from zero-lash, COLD.
2. Warm up engine, that means till the engine is at normal operating temp.
3. Pull all spark plugs.
4. Prop the throttle wide open. Do not open wide for each one.
5. Pull the coil wire off the distributor and the coil.
5a. If HEI equiped, disconnect the large red or pink wire going to the HEI terminal.
6. Connect new compression tester to a cylinder to test. Start at #1.
7. Crank engine with starter till the gauge on tester quits increasing.
8. Write down reading on a piece of paper numbered 1-8.
9. Repeat steps 6-8 till you have tested all 8 cylinders.
10. Post your results so we can maybe help you further.

If you can't accomplish #1 then there is not much need to check compression.

When you are finished adjusting the lifters, look at the amount of threads sticking above the adjusting nut. If all nuts are the same, and no stud has pulled out of the head, and the cam lobes are OK, and there is nothing else broken or bent, there should be about the same number of threads above all adjusting nuts. If not, find out why not.
 
#19 ·
two things can cause a rocker to become loose.

a) wear.
b) the nut backed off.

a is much more common, usually the cam lobe going away.. but occasionally those lock nuts can back themselves off and you just need to replace the nut and re-lash it.

if the cam lobe is going away, the valve won't open as much. to accurately check the cam lobes, you need to set up a dial indicator and measure all of the rockers. if you know the cam specs, compare your measured numbers to that, if you don't, the numbers should all be within a close tolerance of each other (I think about 10% is normal) remember that intake and exhaust lift numbers can be different...
 
#20 ·
I am sorry my posts are confusing. i have been just as confused as anything else overdrive. it seems like I am constantly coming across something new that seems like it might be an issue. But I have 4 days off this week. So I am going to rent the compression tester adn be doing that. I did get a chance to get underneath the car yesterday for a bit. found the motor mounts were bad. i bought some replacements. got them installed but the damn passenger-side bolt won't line up to save my life. So I will be elbow deep into it Thursday. So I will definitely do what you suggested. I will check the valves as well. As far as I know they had never been touched other than the one that I found loose and I just tightened it down so I wouldn't damage it or the push-rod. So I will check the lash on them. So again sorry it seemed very confusing. It just gets to a point that what you initially find as the problem and fix it. Just doesn't help out at all. I just think it is time to buy a built 383 from Engine factory adn call it a day LOL
 
#21 ·
kc8oye said:
two things can cause a rocker to become loose.

a) wear.
b) the nut backed off.

a is much more common, usually the cam lobe going away.. but occasionally those lock nuts can back themselves off and you just need to replace the nut and re-lash it.

if the cam lobe is going away, the valve won't open as much. to accurately check the cam lobes, you need to set up a dial indicator and measure all of the rockers. if you know the cam specs, compare your measured numbers to that, if you don't, the numbers should all be within a close tolerance of each other (I think about 10% is normal) remember that intake and exhaust lift numbers can be different...

or 3

A rocker arm stud could be pulling out. If he doesn't have screw in studs.
 
#23 ·
bowtie76 said:
. As far as I know they had never been touched other than the one that I found loose and I just tightened it down so I wouldn't damage it or the push-rod.
uhhhh... how exactly did you 'just tighten it down' ?
did you follow the correct procedure for setting valve lash? or did you just crank it down as far as it would go?
 
#25 ·
that could well be your miss right there.

you need to set that rocker correctly.

get that cylinder to TDC _COMPRESSION_ stroke. (put your thumb over the sparkplug hole, you'll feel the compression stroke start)

then if you can't see into the spark plug hole, I find a screwdriver works well to put in the hole, and turn the engine BY HAND.. dont' bump it with the starter if you have something inside the cylinder! once the piston is at the top..

loosen the rocker nut until you can move the pushrod up and down between the lifter and the rocker.
then slowly tighten the nut back down until you can only just barely move the rod up and down. now twirl the rod back and forth between your fingers while you continue to tighten the nut. as soon as you feel any resistance at all, stop. now add 1/2 turn to the rocker and you are done.
 
#26 ·
I will do that here in a few KC. I was checking the timing when A buddy here at work said there was a puddle under the car. I turned the car off and looked and Now I am leaking tranny fluid from the cooler line. i just replaced it a few weeks ago. Some how it has a pin hole in it So I will be tackling that tomorrow. But I will def do what you are saying and check the valve lash on all the cylinders not just the one. Thanks for the help. I am hoping that all these issues will go away soon. Well at least for a short period of time. LOL I need a mental break as well as my pocket book
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top