Can you "over rev" an engine?

Stever89 · Mar 30, 2011

I mean of course you can, till it blows up, but...

I got on it pretty hard the other day, around 6500 or a little higher, no problem, ran great nothing noticed at the time, no boom, no smoke, fluid or flying parts. It just seems to have lost power since then. No one else (friends) noticed it, but I sure have.

It's a typical 302, roush 200s, victor Jr, Edelbrock 600 and rollers.

It still runs fine, but under load it's just not pulling like it was. Any advice? Did I kill it? I haven't done anything yet, but I thought I'd start with a compression test and new plugs, maybe check the timing.

90lxcoupe · Mar 30, 2011

Stever89 said:
I mean of course you can, till it blows up, but...

I got on it pretty hard the other day, around 6500 or a little higher, no problem, ran great nothing noticed at the time, no boom, no smoke, fluid or flying parts. It just seems to have lost power since then. No one else (friends) noticed it, but I sure have.

It's a typical 302, roush 200s, victor Jr, Edelbrock 600 and rollers.

It still runs fine, but under load it's just not pulling like it was. Any advice? Did I kill it? I haven't done anything yet, but I thought I'd start with a compression test and new plugs, maybe check the timing.

Compression test and check the valvetrain out. Also, 6500 on what tach?

03ghoststang · Mar 30, 2011

yes u can over rev and float the valves ....and maybe have it smack the piston........u can probably have a slightly bent valved

FastDriver · Mar 31, 2011

You're probably fine. If you're still running the stock limiter, you only went to 6250. The stock tach is never accurate.

NIKwoaC · Mar 31, 2011

It's a V8 conversion with a carb, right? Probably doesn't have a limiter.

Stever89 · Mar 31, 2011

NikwoaC said:
It's a V8 conversion with a carb, right? Probably doesn't have a limiter.

Right, no limiter, carbed V8 conversion.... and a stock 5.0 tach.

I'm going to get my compression tester on it this weekend.

Mavrick · Mar 31, 2011

6500rpm should be fine. I took my old 89 to the rev limiter 6250 many times with no issues. If you bent a valve, you would notice a misfire. If the car runs smooth still, then i doubt you did any damage.

FastDriver · Apr 1, 2011

Whoops, missed the carb. Kinda hard for the stock computer to cut fuel with you have one of those

Stever89 · Apr 1, 2011

Mavrick said:
6500rpm should be fine. I took my old 89 to the rev limiter 6250 many times with no issues. If you bent a valve, you would notice a misfire. If the car runs smooth still, then i doubt you did any damage.

No misfire. Still runnin' on all 8. I'm going to run compression check anyway.

I know I made a comment about this motor not running well on 87 a while back and everyone seemed to think it was something else, but I'm telling ya, it just doesn't run worth a damn unless it's got 93 AND Lucas octane booster.

RangerJoe · Apr 1, 2011

Spring Pressure

If you have a way, check your spring pressures, make sure they are still within spec. If you have made them weak they may not be closing the valves all the way at high RPM. I would think you would damage a valve or piston, but I guess its possible that they haven't made contact yet.

Stever89 · Apr 3, 2011

130-140 psi all cylinders. I don't know... I'll pull the valve covers and take a look next.

Wildstringer · Apr 3, 2011

anything that you could have done to the engine by over reving it, would be followed by smoke, some type of noise or a vibration. for example bent valve you would have a lifter tap since the valve would not be closing all the way. rod knock. piston issues would have smoke or vibration.

BlackGT89 · Apr 3, 2011

If you rev with no load (in neutral or with the clutch in) you might could do some damage. If you had a load on it, you probably couldn't hurt it unless you were really trying to and it was sustained for some time. One sure way to over rev an engine it to downshift at too high of a speed for that gear (rev limiter or not). You might just have a case of racer's remorse.

Stever89 · Apr 4, 2011

Wildstringer said:
anything that you could have done to the engine by over reving it, would be followed by smoke, some type of noise or a vibration. for example bent valve you would have a lifter tap since the valve would not be closing all the way. rod knock. piston issues would have smoke or vibration.

No, nothing like that, thankfully. I took it for a drive yesterday and it runs great. I'm just not feeling it run as strong as it was.

Stever89 · Apr 4, 2011

BlackGT89 said:
If you rev with no load (in neutral or with the clutch in) you might could do some damage. If you had a load on it, you probably couldn't hurt it unless you were really trying to and it was sustained for some time. One sure way to over rev an engine it to downshift at too high of a speed for that gear (rev limiter or not). You might just have a case of racer's remorse.

"Racers remorse"...mmm. Could be. I really wound it up (just a hard launch).

90lxcoupe · Apr 4, 2011

Wildstringer said:
anything that you could have done to the engine by over reving it, would be followed by smoke, some type of noise or a vibration. for example bent valve you would have a lifter tap since the valve would not be closing all the way. rod knock. piston issues would have smoke or vibration.

You could have bent valves without really knowing it.

If it was the stock tach i wouldnt worry about it, but get a MSD box with a rev limiter before you really hurt something... This happened to me and i made a custom piston valve

Flavadave4 · Apr 4, 2011

90lxcoupe said:
You could have bent valves without really knowing it.

If it was the stock tach i wouldnt worry about it, but get a MSD box with a rev limiter before you really hurt something... This happened to me and i made a custom piston valve

LOL, made for you...by you!

Stever89 · Apr 4, 2011

90lxcoupe said:
You could have bent valves without really knowing it.

If it was the stock tach i wouldnt worry about it, but get a MSD box with a rev limiter before you really hurt something... This happened to me and i made a custom piston valve

Good advice... thanks

Can you "over rev" an engine?

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Can you "over rev" an engine?

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