If you hold a carbureted chevy 2.8 to the floor will the valves float before damage is done?


#1

Early 80’s Chevy 2.8 in a s-10 pickup either an 83 or 84, if you hold the pedal to the floor with the car in neutral will the valves float? Or will something fly apart? The engine is in good condition and runs good, and has about 80k miles on it.

There is a guy at work that does mowing and he always door dings people with that truck so we were thinking of playing a little joke on him by wiring the throttle wide open so when he starts the truck we startle him. We have already jacked up and blocked the rear wheel, tied pop cans to the undercarriage, and lit a smoke bomb under his hood and told him his truck was on fire and he came running out and emptied a fire extinguisher under the hood.

We probably wont actually do this, but the subject came up, will valves float?

We already thought he might panic and pop the truck into gear and go flying into someone so we probably wont do it, so at this point its more of a technical discussion.


#2

Not a good idea…


#3

You mean will the valves float before the pistons and rods fly apart? Not something I would do as an adult.

In our parking garage, stall were pretty narrow to jam as many cars in as possible. Our lab director complained about getting his car dinged from careless people. What he finally did was drape a long piece of roll corrugated shipping material along the side of his car. It not only protected his car but told everyone else how careless they were.


#4

The early 2.8s were not a robust engine and if held wide open throttle I’d bet $100 that the bottom end (rods, bearings, etc) would let loose before part of the valvetrain would. Sounds like a good way to ruin an engine.


#5

@bing

Sounds like a good idea, we may try the bubble wrap method. We can try to shame him into being more careful.


#6

@WheresRick, you going to bubble wrap your cars or his to get the point across?

Auto parts stores used to sell these ugly black rubber bumpers that you could install on your doors to keep from dinging other people’s cars. Maybe you could install some on his.


#7

@rodknox
Au contraire. Wiring the throttle open ? I think it’s a “great” ( dumb) idea and OP ought to give it a try and let us know the outcome. The only time this would be a valid is if the motor were in good condition. Otherwise, it means nothing. It can’t buy the farm too early. It wouldn’t be effective. Just in case, take up a collection to cover expenses. Sounds a little like adult “bullying” though. Heck, it may be his only form of transportation and you want to possibly destroy his car…for door dings ? " we probably won’t do this." You ought to have your collective heads examine if you do. You have now gone from practical joke to criminal behavior ! I might want to ask the business to give the guy his own extra wide designated parking space. That would be a cool, non trouble making form of practical joke ! It may be “a little joke” to you to have your car motor destroyed. You guys must make a lot of money at your job.


#8

A neighbor was showing off a new '57 T’bird and was gunning the motor in neutral to thrill us kids. The throttle stuck full open and the motor rev’d and rev’d and blew up before the startled driver could find the ignition key to turn it off. It was thrilling watching the tow truck take the smoking new car away and the puddle of oil on the ground was impressive.

Floating valves on a motor with no load on it won’t make a difference, it will rev till she blows unless there is a computer control or governor somewhere in the system to limit the rpm’s.


#9

Ok, Im not going to do it, I will talk everyone out of it.

To be fair, we all love the guy that was to be the subject of the prank, we wouldn’t want to cause him any kind of harm. He has a brand new minivan that his wife drives and an older minivan as well. The s10 is his truck he bought to replace an old tempo.

He drove in one morning to open up at 530am and drove that tempo over a parking island and blew 2 tires, we all gave him a hard time but in the end we helped him and took the rims to get new tires mounted. Then there was the time he shut the truck off in drive and walked away and the truck rolled out of its spot.

He also changed the blades on the mower and put them on backwards, then proceeded to mow all morning, the grass looked like hell and when we came in for lunch we asked him what was going on. We just like to rib him, he ribs us back as well when we do something stupid.

Hes one of those rare people as in when you are having a bad day, talking to him will put you in a good mood, hes a great guy. Its just that hes older, and a bigger guy so when he gets out of anything he flings the door open, I have seen him door ding several people, the straw that broke the camels back was one guy bought a new chrysler 200 and it was door dinged the first week he had it by our subject.
We have shamed him into parking away from everyone.

It all started when it was suggested to wire his throttle open ( I didn’t suggest it believe it or not). I said we would blow the motor on his truck, well another guy said the valves will float before any damage is done. He said that its designed that way. I just want some info on valve float so I can argue with him next week.


#10

“another guy said the valves will float before any damage is done. He said that its designed that way.”

No car is designed with valve float. Valve float happens when the car ages (or is modified improperly) and the valve springs are no longer strong or fast enough to close the valves as fast as they need to at high rpms.


#11

I hear you Rick and it is all well and good to talk anyone out of the thought for everyone’s sake. A well liked person can be treated with positive constructive humor. He should get his own parking space well away or plenty wide with a special sign with his name on it. Out nice the people you really care about and find the most rewarding way to change their behavior that affects you personally…that’s my very humble opinion. It works with everyone who you value as a friend. Having said that, if the niceties don’t work, then, that shows how little respect and concern they have for you. But, I would never be malicious with a coworker. It always backfires on everyone.


#12

@asemaster

Ok, thats what I thought, this guy said back in the day he had a mustang and the valves would float before he did any damage to the motor. I called bs on that, but I will continue my debate with him on monday.


#13

@dagosa

Well put. This guy is a retired teacher and has two masters degrees, he is very smart, sometimes he just lacks any common sense with certain things, and hes forgetful.


#14

this guy said back in the day he had a mustang and the valves would float before he did any damage to the motor.

That may very well be the case, but it was probably because he put a big-ass camshaft in it and didn’t upgrade the valve springs as well. It certainly wasn’t designed that way.


#15

Valve float may or may not damage an engine. There is no set answer.
It’s possible for rod bearing wear to cause a connecting rod, or plural, to come loose at or before the point where the valves start floating.

It’s also possible for valve stem keepers to become dislodged during valve float and that could lead to the valve dropping into the cylinder at high RPM.
Valve float can also be determined by age and weakness of the valve springs, etc.
Needless to say, either of those scenarios will lead to catastrophic damage.


#16

Sometimes on the old hydraulic lifters on Chevy SB engines you could foam the oil and basically collapse the lifters,but on a newer engine with modern oil-NO!-Kevin


#17

There used to be wagering competition on how long a subject engine would hold together. One would take a vehicle that was ready for junking; place a concrete brick on the gas pedal; start it; and let it rev until the engine quit or disintegrated. The wagered time that came the closest to the actual indurance won the pot.

I, also, heard on the grape vine, that someone heard a Transam crank up and immediate rev for the red line. It was shut down in time. This was repeated a few times until someone looked under the hood. Turns out the Thermoquad on the 455 had been stolen; the fuel line was lined up with the intake manifold; and was squirting directly into the open bores. I guess the engine held together.


#18

Remember the old car buy back program. Whatever they dumped in the tank and ran the engines to blow them up-some of those cars just didn’t want to give it up.


#19
He should get his own parking space well away or plenty wide with a special sign with his name on it

Paint a space about as large as a semi truck, width and length, and paint his name inbetween the lines.


#20

@Bing: They put sodium silicate in the crankcase to destroy the bearings and seize the engine. Some of the cars started up and locked in seconds. One video I saw showed an old Dodge B series van screaming, knocking, and smoking for minutes. The video claimed they had drained the coolant, added the liquid glass, and placed a brick on the accelerator 45 minutes ago. It finally blew several minutes into the video.