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Topic: Timing Set Problem

in Forum: C3 Engines


Timing Set Problem

Posted: 4/27/06 6:51pm Message 21 of 37
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ORLANDO, FL - USA
Joined: 12/11/2002
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Vette(s): 1980 L82 Dark Metallic Green Coupe, Gymkhana Suspension, AM/FM/CB, GM ZZ383....nice....

Well removed carb, distributor, hoses, and intake. All came off fine. More bad news. Got all of the rods out but found that some of the lower pieces that the rods fit into (hydralic lifter?) were raised up and damaged in most of the same locations where the rods were bent. Some had a few of the brown phenolic looking pieces broken out and laying there. Tried to push it down but it will not go. Not sure what would cause this failure? 

FLA VETTE38834.8175462963


 
1980 L82 (5069 made), Dark Green Metalic (844 made)
Gymkhana Suspension, AM/FM/CB, Sporting a ZZ383......... 
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Timing Set Problem

Posted: 4/27/06 7:21pm Message 22 of 37
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Duncanville, TX - USA
Joined: 11/8/2003
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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
Sounds like time for a new cam/lifters/pushrods. That sux.


Joel Adams
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Timing Set Problem

Posted: 4/27/06 7:32pm Message 23 of 37
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ORLANDO, FL - USA
Joined: 12/11/2002
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Vette(s): 1980 L82 Dark Metallic Green Coupe, Gymkhana Suspension, AM/FM/CB, GM ZZ383....nice....
So what do you think was the root cause? Timing chain cam gear stripped? cam failure? hydraulic lifter failure? rod failure? something else?


 
1980 L82 (5069 made), Dark Green Metalic (844 made)
Gymkhana Suspension, AM/FM/CB, Sporting a ZZ383......... 

Timing Set Problem

Posted: 4/27/06 7:57pm Message 24 of 37
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Duncanville, TX - USA
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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
Bernie, without actually seeing what you're seeing, its hard to say. It most likely is a combination of things that led to this happening.
It could simply be that some of the lifters took a poop. The thing is, tho, that normaly does not create broken p-rods. I think you may want to have a look at the valve springs, and see if there is evidence of any "coil bind" on them, especially the cyls. with the broken rods. If the springs are binding, it will bend/break p-rods.
It could also be that the valve adjustments were too tight, and when you ran the engine up on your last run, the lifters pumped up, and just created a bind on the valve-springs, bending the p-rods.
(I'm sure Ken could explain this much better than I can.)


Joel Adams
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Timing Set Problem

Posted: 4/28/06 3:52pm Message 25 of 37
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Virginia City, NV - USA
Joined: 1/19/2005
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K. Styer & J. Adams, (sounds like a law firm, don't it?) I've been adjusting valves by the base circle method for a long time. Most of the pro drag racing teams do it the same way. Have either of you done it that way, and what do you think of it??

Dave




Timing Set Problem

Posted: 4/28/06 6:28pm Message 26 of 37
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CUYAHOGA FALLS, OH - USA
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Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

Just an odd thought, do your lifters actually have a problem?  Some of them are up in any engine positions.  If you turn the engine you may see the ones sticking up will go down and others rise, normal operation.

If the tops all look the same except for position it's okay.  But if the center of the lifters don't match the outer barrel, the lifters could have a problem.  If the tops of the lifters are out of place they are shot.   There should not be any brown phenolic pieces from inside the lifters.  You may be seeing pieces of old baked valve seals, or after market rod guides.

As Joel said before, over revving the engine is the most common problem.  This is very easy to accomplish if you down shift too soon.

What else Joel was saying, if the springs are weak, or if the rockers bind and in either case cause the valves to close too slowly, the lifters and valve train get some slack in them as the cam lobe drops away.  This can cause lifters to pump up after a few revolutions, and over fill.  As the engine starts to slow down, the valves try to open too far (already binding) and the pressure on the valve train rises sharply and the rods can't handle it, so they bend.  Over revving the engine actually is a similar reaction, but the binding friction comes from the speed and mass of the valve train parts.  The extra strain occours even without the lifters pumping up.  This is why over rev will cause solid lifter cars to do the same thing.  Too much oil pressure can contribute to this problem.




Timing Set Problem

Posted: 4/28/06 6:42pm Message 27 of 37
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Duncanville, TX - USA
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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
[QUOTE=Pumps]

K. Styer & J. Adams, (sounds like a law firm, don't it?)...

Dave

[/QUOTE]

Except we don't charge $500 per hour for talking to someone on the phone!

Dave, if you're talking about adjusting the valves with the lifter all the way down(base circle of the cam), then yes, that's how I do it. This is the best way to get your initial adjustment, and pretty much the only way to do it on a solid lifter cam.

Ken, thanks for the clarification! I find it really hard to explain "tech" stuff to where anyone else but me can understand it!


Joel Adams
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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Timing Set Problem

Posted: 4/29/06 8:25am Message 28 of 37
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
Joel thats why we make a good team,  but if I make it to PF I'm not going to stand next to you until after the WHACKING!  I don't want caught in the crossfire!


Timing Set Problem

Posted: 4/29/06 4:39pm Message 29 of 37
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ORLANDO, FL - USA
Joined: 12/11/2002
Posts: 459
Vette(s): 1980 L82 Dark Metallic Green Coupe, Gymkhana Suspension, AM/FM/CB, GM ZZ383....nice....




 
1980 L82 (5069 made), Dark Green Metalic (844 made)
Gymkhana Suspension, AM/FM/CB, Sporting a ZZ383......... 

Timing Set Problem

Posted: 4/29/06 4:41pm Message 30 of 37
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ORLANDO, FL - USA
Joined: 12/11/2002
Posts: 459
Vette(s): 1980 L82 Dark Metallic Green Coupe, Gymkhana Suspension, AM/FM/CB, GM ZZ383....nice....

This is my first time posting with a picture. Not sure how to add text with the photo.

What are the brown pieces?




 
1980 L82 (5069 made), Dark Green Metalic (844 made)
Gymkhana Suspension, AM/FM/CB, Sporting a ZZ383......... 

in Forum: C3 Engines


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