Overrev
#1
Pro
Thread Starter
Overrev
So I messed up a bit and threw 1st instead of 3rd at the higher end of 2nd. Maybe like 75-80. Felt the higher than normal rev and the fuel cut off hitting immediately which dropped my speed with a quickness. I also kicked the clutch into neutral. The afterimage of the rev limiter showed 6800-6900. No lights or wired sounds just yet, thoughts?
#2
Premium Supporting Vendor
So I messed up a bit and threw 1st instead of 3rd at the higher end of 2nd. Maybe like 75-80. Felt the higher than normal rev and the fuel cut off hitting immediately which dropped my speed with a quickness. I also kicked the clutch into neutral. The afterimage of the rev limiter showed 6800-6900. No lights or wired sounds just yet, thoughts?
#4
Premium Supporting Vendor
Assuming you were doing 80 in first and you completely let the clutch out that would be an 8000rpm over-rev. It's "probably" fine, but valve springs are cheap compared to LT4 crate engines. I would put new valve springs on it.
Last season I had mechanical over-rev when going from 2-3 at 90mph and hit first. 9000rpm on the PDR data. I realized it very quickly and probably didn't even have the clutch fully engaged. I replaced valve springs as a precaution and checked the spring pressures, which were all within spec.
Last season I had mechanical over-rev when going from 2-3 at 90mph and hit first. 9000rpm on the PDR data. I realized it very quickly and probably didn't even have the clutch fully engaged. I replaced valve springs as a precaution and checked the spring pressures, which were all within spec.
#5
Le Mans Master
So I messed up a bit and threw 1st instead of 3rd at the higher end of 2nd. Maybe like 75-80. Felt the higher than normal rev and the fuel cut off hitting immediately which dropped my speed with a quickness. I also kicked the clutch into neutral. The afterimage of the rev limiter showed 6800-6900. No lights or wired sounds just yet, thoughts?
Last edited by Mr. Gizmo; 02-12-2019 at 05:11 PM.
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vdavenp802 (02-13-2019)
#6
Pro
Thread Starter
#7
Le Mans Master
same thing won’t make a difference if it’s an ls7 or lt4. Hard mechanical over rev does an engine in. Back in the day a friend power shift first when wanting 3rd in his 396 Chevelle. The car ran fine for a couple of months then dropped a valve.
Last edited by Mr. Gizmo; 02-12-2019 at 05:12 PM.
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Raysmuffler (07-30-2019)
#8
Come on now..... stop trying to scare the hell out of the Op.
More often than not he will be fine. 6900 rpm will not likely hurt this motor.
It is more likely the op could have damaged the transmission.
I am betting neither was damaged.
More often than not he will be fine. 6900 rpm will not likely hurt this motor.
It is more likely the op could have damaged the transmission.
I am betting neither was damaged.
#9
Le Mans Master
maybe / maybe not. If he was wringing it out in second gear. That’s probably close to 90 mph when he slammed 1st gear. All the more reason not to buy one of these dogs used.
#11
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If it's not making funny noises, you're probably fine. I remember driving my 65 L79 back in the 70's. We stuffed two girls in the Vette with my buddy and I. I was 6 grand in 3rd gear, tried to hit 4th, but hit the girl's leg straddling the shifter and went into 2nd gear. The tach buried and it felt like i slammed the brakes on. I pushed in the clutch and it idled fine.
Never had an issue with the motor. Still have the 65. Still know the girl.
Never had an issue with the motor. Still have the 65. Still know the girl.
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Dane@LGmotorsports (02-15-2019)
#12
Melting Slicks
#13
#14
Le Mans Master
Happened to me at least 5 times!! For the life of me i cant understand why the 1st is so easy to shift compared to the 3rd!! Never happened to me before the C7z!!!
So anyway it ran fine each time afterward, so i wouldnt worry, because damage would be right away!! Changing valve springs is useless , unless it sounds like a broken spring. Mine dynoed 698whp and 757wtq 6 months after that and still run strong!!!
btw a leak down test was performed also 6 months afterward, and was perfect!! A broken spring would have a caused a serious leak!!
So anyway it ran fine each time afterward, so i wouldnt worry, because damage would be right away!! Changing valve springs is useless , unless it sounds like a broken spring. Mine dynoed 698whp and 757wtq 6 months after that and still run strong!!!
btw a leak down test was performed also 6 months afterward, and was perfect!! A broken spring would have a caused a serious leak!!
Last edited by timmyZ06; 02-12-2019 at 08:29 PM.
#15
I had WS6 Trans Am and just did the heads and cam. I also put 4.73 gears in the rear end. First track night went from high 3rd down to 2nd instead of 4th. Springs were fine. Bent all the valves though, tough night. You would know if there’s a problem. Thanks
#17
Le Mans Master
#18
Without data to determine how high the motor was spun I would trust the guy that actually builds race motors for a living (Jason).
#20
Originally Posted by timmyZ06
Maybe not everyone dont care about swapping valve springs for fun! Do you really think it will fail few thousands miles later??!!