81 350 Engine noise
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81 350 Engine noise
After getting on it from a red light I started to hear a noise. After arriving at home I lifted the hood and at first I thought it was the water pump. So I changed it and stated it up and the noise sounded worse than before.So I took off the belts and still the same. Sounds like someone in the engine with a ballpeen hammer.Almost goes away at idle,but bring up the RPMs and hammering starts. It does not seem to miss or run and different. Please help... Thanks Randy
Le Mans Master
Joined: Jan 2006
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From: Boca Raton Florida
what part of the engine is the noise coming from? Is it hammering or clacking? might just be a collapsed lifter or rocker nut backed off. If it is hammering it can be a bad bearing. Look at the exhaust manifold gaskets, could easily be a leak.
Good Luck, let us know
Good Luck, let us know
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Ok pulled valve cover off and on passenger side one of the rockers looked like it was off to the one side. So I grabbed ahold of it and there is about half an inch play back and forth.Not really loose but I could move it back and forth. Is that maybe the problem???
Melting Slicks
Joined: Jan 2004
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From: New Cumberland PA
If it's an automatic, put it in gear and step on the brake and the other foot on the throttle. If the noise picks up more than the rpms, I would say it a bearing. A lifter is more of a tick, a bearing is more of thud or hammer sound.
Instructor
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81's are famous for the cam's going flat made of butter let me guess you have around 80,000 miles on your engine???? if not I would recomend a valve job if you do not know how and want to learn there are some great threads here on it or type in valve adustment on google I would explain but I am not a pro so do not wish to give bad advice if the cam is not flat one of the retaing bolts may have gotten loose the one turned to the side !! Oh yeah I have an 81 with 80,000 miles on it.
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Melting Slicks
Joined: Feb 1999
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From: New Paltz, New York USA
I don't think that you should be able to move your rocker back and forth a half an inch. Look for the lars method of valve adjusting and try to adjust your valves. I did my 81 and it made it a lot quieter. Good luck.
Le Mans Master
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From: Boca Raton Florida
LOL, No you should definately NOT be able to move the rocker a half inch. Back the nut off, realign the rocker and rod on the valve. Rotate the crank so that vallve is off the lobe and then readjust the valve. Fire it up and make sure the valve is working, moves he same amount as the others. There is a possibility that the cam lobe is wiped, but maybe the nut just backed off
Abby Normal
Joined: Dec 2001
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From: Press "2" for English
yup, rocker arm is your problem. question is, why?
check the pushrod, but i'd bet that the cam is 'flat'. once you get everything back together, run the engine with the valve covers off. be prepared because this WILL make a mess. you won't have to run it very long but if you have a bad cam, one (or two, or three...) rockers won't seem to move as much as the others.
http://store.summitracing.com/partde...5&autoview=sku
check the pushrod, but i'd bet that the cam is 'flat'. once you get everything back together, run the engine with the valve covers off. be prepared because this WILL make a mess. you won't have to run it very long but if you have a bad cam, one (or two, or three...) rockers won't seem to move as much as the others.
http://store.summitracing.com/partde...5&autoview=sku
Melting Slicks
Joined: Nov 2005
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From: Green Valley Arizona
Originally Posted by 81vettelover1
Ok pulled valve cover off and on passenger side one of the rockers looked like it was off to the one side. So I grabbed ahold of it and there is about half an inch play back and forth.Not really loose but I could move it back and forth. Is that maybe the problem???
Do a visual check on the stud height of that one rocker...bet it has come out a bit. You can drive it back it and it will stay for awhile...but not a long while. Time to pull those heads and throw them away. They are also most likely cracked. Time to spend some money and get a nice set of heads.....but ouch....its going to cost a bit.
Let us know what you find.
LannyL81
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Ok here is the rest of the story. I pulled the heads off and the one rocker that was sitting sideways was all beat up where it ride s on the valve.Also the top of the valve was beat up. Then I look and I guess what happened was the rocker must of came loose and about cut the stud in half. So I took both heads to the machine shop for inspection and now just waiting for the word back. Not really sure at this point about doing a valve job on the old heads or buying new ones.Will I gain anything with new heads?
Le Mans Master
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From: Boca Raton Florida
doing a valve job is a good idea if your going to put the old heads back on. you still need to knoe what the story is on the cam, and you need to find out before putting the heads back on. you can do this with a gauge that is used to measure cam lobe lift.
Anyone got a pic of this thing?
Or, just put in the kit that clutchdust posted.
OR, new heads and all that, downside is more $$, upside is lots more hp to be gained, but more mods will be needed to realise them, like dual exhaust. This is an 81 with the ECM and there is a LOT you can do to wake it up and keep the ecm.
so you need to make up your mind which way to go, just get it back on the road, or serious mod
let us know, be happy to help you spend $$
Anyone got a pic of this thing?
Or, just put in the kit that clutchdust posted.
OR, new heads and all that, downside is more $$, upside is lots more hp to be gained, but more mods will be needed to realise them, like dual exhaust. This is an 81 with the ECM and there is a LOT you can do to wake it up and keep the ecm.
so you need to make up your mind which way to go, just get it back on the road, or serious mod
let us know, be happy to help you spend $$
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Sixfooter, thanks for the info. I guess I better do the new cam cause I dont want to go thru this again. I have done away with the ecm except for the torque converter hook up. I had already changed out the dist with a malloy and went back to non computer rochester carb.
Race Director
Joined: May 2004
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This stuff can cost you a lot money if you do it little by little.
Me, I would pull the engine.
Buy a nice crate engine for a sensible price, drop it in and play to your hearts content without fear of more stuff happening.
If you wish to keep the original engine, you can now take it apart in your garage and play with it for a month or ten years whatever pleases you. Build it back to original, shine it up and drink a toast on it every so often while it sits nice and shiny on an engine stand in your garage.
Just my .02
Me, I would pull the engine.
Buy a nice crate engine for a sensible price, drop it in and play to your hearts content without fear of more stuff happening.
If you wish to keep the original engine, you can now take it apart in your garage and play with it for a month or ten years whatever pleases you. Build it back to original, shine it up and drink a toast on it every so often while it sits nice and shiny on an engine stand in your garage.
Just my .02