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7/16/13 11:20am - Original Message: 'Engine rattle above 2000 rpm'
Case75
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230

I've discovered an engine rattle above 2000 rpm. It happens even when the car is in park. Crank bearings? I can feel it when I put my hand on top of the air cleaner.



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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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7/16/13 12:24pm - Reply: 'Re: Engine rattle above 2000 rpm'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Ruh Roh!
You say you can "feel" it...is it a noise, or a vibration....or both?

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Joel Adams
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7/16/13 1:15pm - Reply: 'Re: Engine rattle above 2000 rpm'
Case75
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230
It's both Joel. I've been hearing it for the last 400 or 500 miles. It sounds like a diesel a bit if that is a good description. The oil pressure is right on 40 psi, temp stays around 190 to 200 but every time the revs get over 2000 I can hear it and today when I put my hand on the engine I could feel it too. It idles just fine and is smooth below 2000 rpm. At first I thought the sound was coming from the rear end or the tranny but the noise is there in park.

|UPDATED|7/16/2013 10:15:17 AM (AZT)|/UPDATED|


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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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7/16/13 1:30pm - Reply: 'Re: Engine rattle above 2000 rpm'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19447
Did ya maybe get some crappy gas recently? The "sounds like a diesel" points to spark knock/ping. Is your distributor tight? Perhaps it has moved counterclockwise, advancing the timing too far. That would cause the noise and a rough idle/vibration....

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Joel Adams
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7/16/13 1:52pm - Reply: 'Re: Engine rattle above 2000 rpm'
Case75
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230
I checked the distributor hold down, it's tight. Lugged it up some hills, no noise and it's 90 F outside today and very humid. 3 tanks of gas through it at least. Using Shell premium. Timing is set at 12 degrees. Running ported vacuum. Total timing is 34 degrees at 3000. I don't think it's knocking. When I say diesel, I mean it has that growl. Another description from inside the car is the sound of a playing card in a bicycle spoke amplified 10 times. It's getting worse. I can now hear it at highway speeds even with the windows down and the tops off. I uses to only hear it when the car was closed up. The sound is constant when I'm on the gas and goes away as soon as I let off or at the very least diminishes in volume. I can drive it all day if I stay in town and it sounds fine as long as I accelerate below 2000 rpm.  

|UPDATED|7/16/2013 10:52:13 AM (AZT)|/UPDATED|


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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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7/16/13 11:05pm - Reply: 'Re: Engine rattle above 2000 rpm'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19447
Wow....hard to say what it could be, without actually hearing it, but it may be a rocker arm, or lifter failing, could be that something has gotten on top of one of the pistons(carbon, etc)....so many possibilities. Is there a chance you could get a video, and post it somewhere, so we can maybe hear it?

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Joel Adams
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7/17/13 8:14pm - Reply: 'Re: Engine rattle above 2000 rpm'
stingrayjim jr Lifetime Member
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SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
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Not to sound overly simplistic, but, could it be the pcv valve?? or, some other vacuum related noise?... maybe a line collapsed,brake booster line?... just a thought?? 

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StingrayJim
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7/17/13 8:17pm - Reply: 'Re: Engine rattle above 2000 rpm'
Case75
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230
Adams' Apple said: Wow....hard to say what it could be, without actually hearing it, but it may be a rocker arm, or lifter failing, could be that something has gotten on top of one of the pistons(carbon, etc)....so many possibilities. Is there a chance you could get a video, and post it somewhere, so we can maybe hear it?

Someone else mentioned to me that it may be carbon...Lamp Dunno.
I don't know if it is in the valvetrain as the car idles very well; you would think it would be missing a lot.
 
I'll see about videoing it if I can figure out how to post it.




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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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7/17/13 10:24pm - Reply: 'Re: Engine rattle above 2000 rpm'
VetteCountry Lifetime Member
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Belvidere, IL - USA

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1977 Black T-Top ZZ4 5Sp 16in Wheels


Joined: 10/24/2004
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If you know which side is making noise. Take the valve cover off, cut a 6" wide card board insert in valley to stop oil from getting all over. Start engine and watch rockers for movement. If some are not moving much, I would say cam and lifters are bad.

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7/17/13 10:31pm - Reply: 'Re: Engine rattle above 2000 rpm'
danascar
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Germansville, PA - USA

Vette(s):
1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats

Joined: 1/28/2010
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Try an automotive stethoscope if you can get your hands on one. This was the only way I could find a tap in my engine which turned out to be the fuel pump arm hitting the block. 

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7/18/13 6:29pm - Reply: 'Re: Engine rattle above 2000 rpm'
JohnRR
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Yes, Stethoscopes are cheap and very helpful.  Make sure you check areas all over the engine.  Such as the distributor and on the bellhousing.  Check the valve covers, A/C compressor, fuel pump, etc.

John


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7/18/13 7:12pm - Reply: 'Re: Engine rattle above 2000 rpm'
Case75
Former Member
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230
Thanks for all the suggestions fellas. Really busy with home renovations right now so not much time to work on the Vette. I've got an electrician coming on Monday and drywallers after that. We're renovating the living room and dining room, a bedroom and part of the kitchen. No money or time to play with the Vette.

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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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7/21/13 5:30pm - Reply: 'Re: Engine rattle above 2000 rpm'
Case75
Former Member
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230
Finally got some time to myself today. Got thinking about it being a timing issue as Joel suggested. I had put the vacuum advance back to ported a few days ago with no change; this time I disconected it altogether so now have no vacuum advance. Revved the engine back up and noise is not as bad...so it has to be knocking. I've never heard an engine knock with no load. Got the timing light out and found that the initial had drifted back up to 21 degrees from the 12 degrees I had it at it April even though the hold down was tight. Set the initial back to 12 degrees. Revved it up with the vacuum advance still diconected and knocking is all but gone. Checked the mechanical and I have 32 degrees all in at about 3000. Hooked the vacuum advance back up and it is knocking again. Disconect it and knocking is nearly gone. I did notice too that when I was trying to set the inital, the timing was wondering several degrees. What do you think, distributor? Timing chain? Cam? With the hold down tightened as much as possible I can wiggle the distributor a little bit. I took the car for a drive and I am still getting a bit of knock on the highway sometimes but not all the time like I was. Throttle reponse is pretty lazy now but I don't care about that. I guess the next step is to take a couple of more degrees out of the timing.


Update: Ordered a new distributor today. Rather than repair my old one I've decided to just replace it.

|UPDATED|7/21/2013 2:30:14 PM (AZT)|/UPDATED|


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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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7/21/13 6:27pm - Reply: 'Re: Engine rattle above 2000 rpm'
73 MRVETTE
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it sounds like an ignition timing problem to me. How many miles on the engine?

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7/21/13 8:39pm - Reply: 'Re: Engine rattle above 2000 rpm'
Case75
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230
73 MRVETTE said: it sounds like an ignition timing problem to me. How many miles on the engine?

76,000 miles.



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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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7/21/13 11:04pm - Reply: 'Re: Engine rattle above 2000 rpm'
rod7515 Lifetime Member
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Red Lion, PA - USA

Vette(s):
1974 White 350 Corvette, TH400 Automatic 1972 Tangerine /Go Mango Convertible 383 Stroker, 2004r Automatic

Joined: 10/27/2006
Posts: 1172
Have you taken a look at the balancer to see if the outside ring may be spinning on the inside. Many times the rubber will be drying out and that allows the ring to spin which makes the timing mark jump around. Hope its that simple! Rodney

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7/22/13 9:29am - Reply: 'Re: Engine rattle above 2000 rpm'
Case75
Former Member
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230
rod7515 said: Have you taken a look at the balancer to see if the outside ring may be spinning on the inside. Many times the rubber will be drying out and that allows the ring to spin which makes the timing mark jump around. Hope its that simple! Rodney

Very real possibility Rodney but unfortunately I did check that out and it seems OK.



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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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7/23/13 8:00am - Reply: 'Re: Engine rattle above 2000 rpm'
manchestershark Lifetime Member
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Equinunk, PA - USA

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1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.

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Ermm  How about the advance unit itself, or the weights in the distributor. One spring broke, one weight rusty and stuck, the activatior arm in the unit bent or hung up some how?

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7/23/13 1:08pm - Reply: 'Re: Engine rattle above 2000 rpm'
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Case75 said: I did notice too that when I was trying to set the initial, the timing was wondering several degrees. What do you think, distributor? Timing chain? Cam?


A stretched chain, worn timing gears, worn dist gear or bushings, worn advance weight posts....or just a timing light issue could all cause the mark to jump around. Even a corroded terminal inside the dist cap could do it. To check if the chain is stretched, you can remove the dist cap, and turn the engine by hand a little back & forth. If the rotor on the dist doesn't move until the crank has moved several degrees or more, the chain is stretched. It's normal to see a LITTLE looseness, but not more than a couple of degrees of crank rotation, if that much. But...if you can turn the crank an inch and the rotor doesn't move, there is too much slack in the chain, or the gears are worn, or both.

Worn dist bushings can allow the shaft to flop around, and the timing marks will jump when using a light, as can a worn gear on the dist, or even the drive teeth on the cam. Also, if the cam is moving front to rear, it can do it. The rear cam plug(in the block) could be pushed out a wee bit, or it might not have been installed all the way to begin with.

So many things can cause this issue, as far as the mark jumping around like that. If it is jumping around at 2500 rpms, I would be concerned, but if it is only jumping around at idle, not so much.



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Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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8/11/13 8:55am - Reply: 'Re: Engine rattle above 2000 rpm'
Case75
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, - Canada

Vette(s):
1975 Corvette 383 stroker w/Patriot 190 heads, Eagle stroker kit, Comp 279TH7 cam, DUI distributor, Edelbrock 7116 intake, Edelbrock 1806 carb, Hedman Hedders, TH400 w/TCI Breakaway 2400 stall, Transgo 1-2 shift kit.

Joined: 6/19/2012
Posts: 230
Well, new distributor has not arrived yet but in the mean time, took the car to a show about 25 miles out of town. Babied it all the way there. Noticed some concerning knocking at idle as I was pulling in to park. Started it back up about 8 hours later and knock was gone. Decided to try and make it home on the back roads keeping the speed to about 40 miles an hour. 10 miles out of town the engine made a quite a death rattle and a squeal and quit before I could reach the key. Got it towed home on a flatbed and it now sits in my garage. I guess it wasn't the distributor. Temp was about 190 just before this and oil pressure was running about 38 pounds; a bit lower than usual. My driving season is over for this year. Unhappy

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Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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