Topic: Bent Push rods, broken stud & rocker
in Forum: C3 Engines
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Lifetime MemberSeabeck, WA - USA
Joined: 3/18/2006
Posts: 179
Vette(s): 1981 Red T-Top 450hp / 383ci 3-Speed Auto 63000 12.5 sec 1/4
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My NEW Engine :( 
Barely 1500 miles on it. It was running rough and sounded like a bad spark plug so I just finished cleaning the plugs, changing plug wired, checking timing, then POW !!! sounded like lightning bolts as is all came apart. I was good breaking it in and never got much over 5500 rpm's. Now at least it's under warrenty. But I can't believe it broke. Looking down the push rod holes, you can't even see where 2 of the hydraulic lifters went. Just hoping it can all be fixed without pulling the engine again. 
I did hear a little rocker arm tapping just before it went. I'm trying to figure out what happened and how to make sure it doesn't happen again. I don't know what quality of parts were used, but seems like it should have been a lot stronger. I asked them to build it tough enough to put nos on it. Glad I didn't do that yet. Not sure I will now. I think I need a beer..........
Barely 1500 miles on it. It was running rough and sounded like a bad spark plug so I just finished cleaning the plugs, changing plug wired, checking timing, then POW !!! sounded like lightning bolts as is all came apart. I was good breaking it in and never got much over 5500 rpm's. Now at least it's under warrenty. But I can't believe it broke. Looking down the push rod holes, you can't even see where 2 of the hydraulic lifters went. Just hoping it can all be fixed without pulling the engine again. I did hear a little rocker arm tapping just before it went. I'm trying to figure out what happened and how to make sure it doesn't happen again. I don't know what quality of parts were used, but seems like it should have been a lot stronger. I asked them to build it tough enough to put nos on it. Glad I didn't do that yet. Not sure I will now. I think I need a beer..........SPONSOR AD:: (Our Sponsors help support C3VR)
Man,sorry to hear that,I am pretty sure you'll be pulling it out even if it is under warranty,they are gonna want to see it and tear it down.did you adjust the valves b4 you started it up? it sounds like the piston hit a valve 
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Lifetime MemberHOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
OUCH!!! Sorry t o hear this!
LukesVette 2007-02-03 07:00:39
Sorry t o hear this!
Valve floating and caught by a piston is what this looks and sounds like - odd for both of them though - were you revving the engine to set total timing? Some of the damage was definiftely done prior based on the valve train noise that your heard - my guess is that the damaged roller rocker was one of the initial culprits that let go....
Much over 5500 RPM may be past the recommended max for the motor...What RPM max was quoted for the engine and if you didn't adjust valves, did the the instructions state explicitly that the valves were already adjusted?
Is that a 3rd pushrod that's slightly bent? That stymies me....I could see an issue isolated to a cylinder but...ugh
If yer lookin for GM to honor the WTY, I might not discuss the RPM topic
Good luck!!
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man sorry to hear that, best get her in to the shop, making sure they know that you have to have time to break her in before the trip to carson city.
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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/
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#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
1) Improper assembly...no lube on the rockers
2) P-rods not correct length
3) Valve springs too stout/tall...coil binding
to be continued...
2) P-rods not correct length
3) Valve springs too stout/tall...coil binding
to be continued...
Joel Adams
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Lifetime MemberSeabeck, WA - USA
Joined: 3/18/2006
Posts: 179
Vette(s): 1981 Red T-Top 450hp / 383ci 3-Speed Auto 63000 12.5 sec 1/4
Two pistons were not working correctly when we shorted out one spark plug at a time, as noted that the rpm did not drop when these two were shorted. All others were ok. These two also happened to be the two that
came apart. The engine builder is a business in Tacoma, K&N Engines, that builds high performance racing engines. I had a local shop in Seabeck install the engine, as they do a lot of business with this company and recommended them. I never got a spec on the RPM's or anything else, but I tried to keep it within limits of the old engine although I was told it should be capable of more RPM's than the old stock 350. I know the local shop did not adjust any valves as I was there 95 % of the time working with them. The engine was suppost to be ready to run, minus valve covers, water pume, fuel pump and intake manifold. I have lots of pictures of it as it was being installed. It was tested at K&N and oil pressure readings etc. There is even one more rocker arm, not part of the two that came apart, that feels way too loose. I have no specs for this engine so maybe your right, not the correct length rods or something. Just glad it didn't happen on the way to Carson city and should have pleanty of time to get a fixed one "broken in".....(don't like that word anymore)
Lifetime MemberHOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
Let us know how it works out! We're here for ya if ya need us!!
Love the hood by the way. Does it give more clearance over stock?
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Lifetime MemberSeabeck, WA - USA
Joined: 3/18/2006
Posts: 179
Vette(s): 1981 Red T-Top 450hp / 383ci 3-Speed Auto 63000 12.5 sec 1/4
Thanks, and yes the hood gives a few more inches. I just barely fit right now, but might have to change to a low profile air cleaner if I decide to put the nos on it, (spacer under the carb.)
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Bladenboro, NC - USA
Joined: 1/22/2006
Posts: 1058
Vette(s): 1972 conv., sunfire yellow, blk interior, blk vinyl and convertible top. Off frame restoration with American Speed 383 stroker engine producing 500hp plus a 200hp NOS system. MSD ignition. Hooker super competition headers with chambered exhaust.
Larry, is this the 383 stroker engine that you're talking about?
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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/
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#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
I stated there was no lube on the rockers for a good reason. You can tell that from the pics.
The bottoms of the two rockers,where the fulcrum balls sit are galled from the lack of lubrication. They also are both completely worn thru, tho one is way worse than the other. This damage could be done from the very instant the engine was first fired, if there was not sufficient lube on the rocker balls during assembly.
My theory ?:
The rockers got so worn from lack of lube that they were pushed out of alignment by the pushrods. In doing that, the pushrods started binding in the guide plates. Add all these factors, and you get bent/broken crap. I would have to put this squarely on the engine builder, unless you installed the rockers yourself, or someone else after the engine was "run in" by the builder.
Now, there is still a possibility of the valve springs having too much seat pressure, or being too tall, and coil-binding. Too much seat pressure, whether open pressure or closed, can cause accelerated wear on ball-type rockers. Coil bind can, and normally does create bent p-rods.
Either of these scenarios would still lead you back to the engine builder.
In the photos you posted, I can see that one of the oil holes in one of the rockers is open, but the other appears to be blocked. The one that appears to be blocked is also the one that shows the greatest amount of wear in the ball area. Check the holes to see that they are open, and will allow oil to flow to the rockers from the p-rods.
Also, I can see that the rollers are not contacting the tips of the valve stems squarely. You can see a very pronounced wear pattern on the edge of both of the rollers. Another indication of an alignment problem. (Or...the tips of the valve stems are not machined flat.)
All of this "speculation" is assuming there was sufficient oil pressure available to oil the rockers to begin with, and that this damage is not due to the rockers not having any oil to them while running.(after the initial engine builder run-in)
Looks like a full tear-down is in order, or, at a minimum, the top end.
The bottoms of the two rockers,where the fulcrum balls sit are galled from the lack of lubrication. They also are both completely worn thru, tho one is way worse than the other. This damage could be done from the very instant the engine was first fired, if there was not sufficient lube on the rocker balls during assembly.
My theory ?:
The rockers got so worn from lack of lube that they were pushed out of alignment by the pushrods. In doing that, the pushrods started binding in the guide plates. Add all these factors, and you get bent/broken crap. I would have to put this squarely on the engine builder, unless you installed the rockers yourself, or someone else after the engine was "run in" by the builder.
Now, there is still a possibility of the valve springs having too much seat pressure, or being too tall, and coil-binding. Too much seat pressure, whether open pressure or closed, can cause accelerated wear on ball-type rockers. Coil bind can, and normally does create bent p-rods.
Either of these scenarios would still lead you back to the engine builder.
In the photos you posted, I can see that one of the oil holes in one of the rockers is open, but the other appears to be blocked. The one that appears to be blocked is also the one that shows the greatest amount of wear in the ball area. Check the holes to see that they are open, and will allow oil to flow to the rockers from the p-rods.
Also, I can see that the rollers are not contacting the tips of the valve stems squarely. You can see a very pronounced wear pattern on the edge of both of the rollers. Another indication of an alignment problem. (Or...the tips of the valve stems are not machined flat.)
All of this "speculation" is assuming there was sufficient oil pressure available to oil the rockers to begin with, and that this damage is not due to the rockers not having any oil to them while running.(after the initial engine builder run-in)
Looks like a full tear-down is in order, or, at a minimum, the top end.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
in Forum: C3 Engines
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