I had a painful and potentially expensive experience in my '69 427 Vette yesterday. I was under hard acceleration and shifted 1st to 2nd. WOT. And the throttle stuck wide open. I scrambled to see if it was a floor matt causing it -- nope. Seriously over revved the engine. I turned the key off and coasted onto a side road. When I turned the key I was met with a "bang" that I am hoping was a backfire. On the good side, there was no catastrophic oil loss or smoke. There are no visible signs of damage, but who knows what lurks within. In looking around, I saw what I thought was a broken throttle linkage. The butterfly on the center carb was wide open and I didn't dare try and start it, and I left it in place.

So, in getting ready for the flatbed, I noticed a nut, bolt and a couple washers sitting on the manifold. I removed the air cleaner assembly to collect them to send along with the car to the Corvette specialist that handled the rebuild of all 3 carbs going into last season. I doubt I even have 100 miles on it since the rebuilds, but let's say 200 to be extremely liberal. What I realized is the carburetor linkage is a 2 piece part, connected in the center by the very bolt, nut, and washers I saw sitting on the manifold. It is clear somehow the nut (should be a lock nut) backed itself off that quickly and allowed the linkage to separate, resulting in the WOT and overrev.

I am nervous as hell what has happened to the internals of the engine. I do not run my car to redline. I have never raced it. It is a weekend car in season and does not get the use it should, but I take good care of it. My point is the engine, which I had rebuilt when I bought the car, was in perfect working order. My trusted Corvette specialty shop subbed the carbs out for rebuilding, which I was perfectly fine with. In fact, despite the time it took, I actually welcomed the work being performed by someone who likely can do it blindfolded. But now I am worried whomever did the linkage may have actually been blindfolded. [I assume but do not know the shop sent the carbs but not the manifold. Wouldn't that mean the shop installed the linkage?]

So how pissed should I be? I just made it clear to the owner I know what happened and asked his tech to look at it very carefully. I did not make any threats. What I am looking for here is really how likely it could be my situation was the result of a part failure of some sort that was beyond anybody's control. While anything is possible, it just seems to me someone must have dropped the ball. AND, if the shop connects it back up, and it seems to run ok, to what extent do you all think I should request (or insist upon) a partial tear down to inspect exactly what the condition is of everything. My instinct is I should do exactly that. Opinions will be most appreciated. (Name of shop intentionally omitted)

 

What rpm did the engine hit when it stuck open?

 

It's a Chevrolet. If it had oil in it, doubt you did any harm. Since it didn't come apart @ WOT would say your OK. If it makes you feel better, drain the oil and check it out.

 

What he said....my friend street-raced...when the valves began to "float" he shifted to the next gear. As Gold Dragon said..drain the oil/look and smell for "burned-overheated oil" and for tiny metal particles/replace the filter and put in new oil.

I would get your mechanic shop to drain/change the oil and filter while you watched...then examine the oil.

After that...it's your decision as to an engine oil pan removal and internal inspection.

 

I'd say you're likely fine, as it wasn't hitting redline under load. You'd likely float the valves before harming anything.

 

If it was me I would have someone else in the car and fire it up. Make sure the linkage is all free and operate the linkage by hand with the hood open. This way you can control the linkage. Once I found out the motor is OK, chances are yours is fine hook up the linkage and make sure it is working correctly. I don't trust anyone else working on my car. They are doing it on a flat rate or hourly and move cars through as fast as they can to make money. I double and triple check things. BTW I over reved mine many times when missing a shift. Never hurt anything. I know run rev limiters.

 

I feel your pain. Something like that happened to me in a vehicle (non vette). A rodent of some sort deposited a nut ohan top the engine and it became lodged where the stop-screws is. I felt about like you do, but I didn't have as much time or recent work in my engine. In the end, no damage seemed to happen to me. In your case I guess, give it some time and see how things go. You're probably ok.

 

I am feeling a bit was better seeing the responses. Draining the oil looking for particles and swapping out the fairly new filter is sensible. To answer the question on what RPMs did I hit -- dunno. In the millisecond I took to look down, the tach needle was bouncing at the max. I really do not know what the engine is capable of at WOT -- as noted there was no load. Clutch went to the floor when it happened, so it was spinning freely until I cut it off. It was just up to temp at the time leaving my development. I am not sure how that cuts.

Fingers crossed.

 

You probably bent a pushrod or two, wont hurt anything.
Pull them out, roll them on a flat surface youll see quickly which are bad.

 

Bang was plug firing when you turned key on. Lit the fuel in the exhaust. Several times messing with the 34 hatteras I saw tach reclined at idle. You can't hear the engines on the flybridge. Never hurt anything. Made to spin. And valvesprings are a built-in rev limiter. If you bent a valve you will hear the compression los cranking the starter.

 

Like Derek derek said, when you shut it off you got a raw fuel charge make it through the chamber without being burned. When you cranked it up the raw fuel fired while the intake valve was open or partially open.

 

I'd be looking for a new shop or learn how to do those sort of things myself.

 

Hey, it happens. You've got damage, which I doubt, or you don't.
Bolt it back together and try it out. If good, forget about it.
Or, you could stress out and nothing will happen anyway.
Total bummer, but what can you do?

 

If you have hydraulic lifters, I doubt that you damaged the engine. If it over-revved a lot with solids, who knows? I agree that the full throttle shut down allowed a lot of raw fuel to get into the intake; then it [back]fired when ignition was fired. If it didn't blow the carb off the manifold nor crack the intake, you are probably fine on that count.

Wish you the best. If your shop is good, and they chose the carb shop for the out-sourcing, they will probably own up to any damage done. I would play it cool and wait to hear the status of the engine and whether damage was done or not.

 

Thank you all for the solid advice. As for the comment suggesting I learn to do things like this myself, that comment is born from someone who likely has turned his own wrenches his whole life. Over time I have learned, sometimes the hard way, there are times when it is best to look to others who specialize, whether it is the Corvette shop I having been using for over a decade, or something as simple as the electrician I used when I installed motion sensing lights at my home. My typical experience as a DIY guy is I do all the research I can, start with a sense of optimism, and end up frustrated and cursing under my breath. Win some/lose some. For certain things, like older cars, experience and a good feel for the basics that is gained only over time, I am willing to pay someone else to do a job correctly as opposed to me fumbling through it. For me, the pleasure comes with enjoying the performance, the sounds, and even the smells of driving a classic car. In my dream world, I would have a guy in white overalls that sneaks into my garage each night to make sure My Mistress remains at 100% waiting for me to feel the urge.

In the end, this will work out. I am extremely frustrated the specialists seem to have missed a small but very important detail in a project I paid top dollar for (and did not complain about spending). I hope the shop responds with its best foot forward and gives me a game plan on how they will make up for what happened. I do not want it to be contentious. I will report back what happens for anyone interested.

 

Just curious, what position did the Corvette shop take? do they agree that faulty workmanship potentially factored in here, have they indicated that any damage caused by this would be covered by them or their subbed out vendor?
Certainly seems like there should be some shared responsibility. I would hope that the party's involved here offer more than the shrugging of shoulders.

Best of luck and keep us posted.

ps. Sorry for the redundancy in questions, just saw your last post after I typed this up. I do agree with your position of using experts to handle certain situations. Pay for expertise and expect it to last for a long time. BTW, your car looks beautiful.

 

The center carb linkage should have a shouldered bolt with a nylon lock nut.

 

The center carb linkage should have a shouldered bolt with a nylon lock nut.

 

FWIW, one of my former neighbors worked for the GM's Rochester carburetor division. On a regular basis, they had engines on the dynos, doing testing and calibration runs. Once finished with the "research", the engines were scrapped off. My neighbor told me that once in a while, when things were "slow", before they removed an engine from the dyno, they'd run it up to MAX speed, and just let it sit there, for as long as it would last.

He said they none of them ever let go, as long as the engine was being kept under a "load". If they suddenly removed the load, like if you were racing and missed a shift, then yeah, odds were good they'd scatter. So, OP, if you still had the engine under load, you should be OK...........

 

Interesting side note. I struck up conversations with the guy whose house I ended up in front of when I coasted onto a side road. He lives very close by but I had never met him. He came right out when he heard the roaring engine make its way to his house. He was extremely friendly and helpful and helped push the car partially off the road to his lawn where I left it over night (I know -- horrible. She had never been out for the night). When the flat bed showed up the next morning and got there a minute or two before me, he called my cell to let me know (we had exchanged numbers). His caller ID from before he retired and moved to my town showed up. TONAWANDA. The failure was going to happen, but it was obviously meant to happen exactly when and where it did. Anyone believe things happen for a reason? I believe it more and more all the time.