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At the track, I developed an engine miss. No horrible sounds, just down on power with a miss sound. I pulled the valve covers and found on No. 8 cylinder (valve closest to firewall) there is a 1/2" of up/down play on push rod. I removed the push rod and it is straight, no broken springs.
Now when I re-insert the push rod, it sits a 1/2" lower than the other rods? Is the rod now sitting inside the lifter?
I have a July 11 appt. with my engine builder.
Last edited by Bluefire; Aug 15, 2018 at 02:17 PM.
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
shine a light down the pushrod hole and see if you can tell if the lifter rotated in the bore, hopefully it didn't... does the pushrod or rocker arm tip have any damage?... you might as well pull the intake and valley cover and see if the cam lobe/lifter is visible and look for damage
At the track, I developed an engine miss. No horrible sounds, just down on power with a miss sound. I pulled the valve covers and found on No. 8 cylinder (valve closest to firewall) there is a 1/2" of up/down play on push rod. I removed the push rod and it is straight, no broken springs.
Now when I re-insert the push rod, it sits a 1/2" lower than the other rods? Is the rod now sitting inside the lifter?
I have a July 11 appt. with my engine builder.
Thats what happen to mine. It was a collapsed lifter.
I think the lifter maybe completely broken. I was playing with the push rod in its hole and the rod dropped further into the hole. Now the push rod only sticks out of the head about an inch.
If the lifter collapsed, then it may have been in the "up" position in the lifter tray. When you pushed down on it, it probably just pushed back down on to the camshaft. No big issue there. But it does sounds like the lifter is collapsed, so it's going to have to be fixed. But as mentioned, it's not a terrible job. definitely inspect the pushrod and rocker arm and make sure there's no damage.
Just curious, how many miles on the motor? do you have a different cam?
If the lifter collapsed, then it may have been in the "up" position in the lifter tray. When you pushed down on it, it probably just pushed back down on to the camshaft. No big issue there. But it does sounds like the lifter is collapsed, so it's going to have to be fixed. But as mentioned, it's not a terrible job. definitely inspect the pushrod and rocker arm and make sure there's no damage.
Just curious, how many miles on the motor? do you have a different cam?
Lower end has 82K original miles. The LS1 heads were upgraded to stock LS6 (243) heads and a "medium" sized cam (224/230 .581/.585 113 LSA) was added 5 years and 50K miles ago. After upgrade it was a DD and saw 5 - 6 track days a year.
I'm really not surprised that this happened. Drive hard and stuff breaks.
Yea, stuff happens. Hopefully there's no other damage to speak of and you'll be back in business in no time.
If you're pulling the heads, it might be worth changing the valve springs, especially given the track use. And have you done the trunnion upgrade? If not, it would be fairly simple while you have the rockers off.
Yea, stuff happens. Hopefully there's no other damage to speak of and you'll be back in business in no time.
If you're pulling the heads, it might be worth changing the valve springs, especially given the track use. And have you done the trunnion upgrade? If not, it would be fairly simple while you have the rockers off.
Best of luck. Let us know how it turns out.
Yes, Thanks. I'll pull the heads and check the cam. Currently running the Harland Sharp trunnions.
A roller exploded off of a lifter on #8 cyl. Pieces damaged a second lifter, ate the cam, and oil pump.
Rebuild:
Shaving .020" off of the 243 heads.
New Brian Tolley dual spirngs/seals.
LS7 Lifters
Comp Cam 231/242 .617/.593 LSA 112
FAST 92mm intake manifold.
LS2 Throttle Body.
Haltech Cold air intake.
GM Perf. Oil pump.
Build will be done in a week. Then tune. Should be a Beast!
Last edited by Bluefire; Jul 30, 2018 at 05:33 PM.
Don't pull that lifter out from the top. Pull the cam and remove from the bottom if possible. You might destroy the lifter bore on removal if that lifter has been damaged.
Not sure what your total setup it, but if you are running 5/16" pushrods at high RPM on the track with aftermarket springs you may have been lofting the lifter so I wouldn't be too quick to simply blame the lifter. You probably need to review the entire valve train setup.
Last edited by vettenuts; Jul 26, 2018 at 08:36 AM.
Don't pull that lifter out from the top. Pull the cam and remove from the bottom if possible. You might destroy the lifter bore on removal if that lifter has been damaged.
Not sure what your total setup it, but if you are running 5/16" pushrods at high RPM on the track with aftermarket springs you may have been lofting the lifter so I wouldn't be too quick to simply blame the lifter. You probably need to review the entire valve train setup.
We did have to pull the two lifters from the cam journal and out a valley hole.
I can't speak to the top end setup. I defer to my highly competent engine builder. I'm sure it was correct. He has been building high HP Corvette engines for more than 20 years and is a degreed Mechanical Engineer. I completely trust him.
That's a rather large cam for track use. What are you using for valve springs? I'd seriously consider something beefier than LS7 lifters with that cam...
That's a rather large cam for track use. What are you using for valve springs? I'd seriously consider something beefier than LS7 lifters with that cam...
Guys are using over .650 lifts with these lifters and revving to 8k.
Yea, stuff happens. Hopefully there's no other damage to speak of and you'll be back in business in no time.
If you're pulling the heads, it might be worth changing the valve springs, especially given the track use. And have you done the trunnion upgrade? If not, it would be fairly simple while you have the rockers off.
Best of luck. Let us know how it turns out.
Thank you. I will.
All of the parts have arrived. I found out we are using Brian Tolley dual springs (.650 lift) and using new Harland Sharp roller rockers. Should be done this week. Hopefully before Thursday. I leave for Road America Thursday morning for the IMSA Race.
Update:
The build is complete and it's a beast. Initial tune on loaded dyno was 427 hp 390 tq. Unfortunately, this was a hot humid 95° day.
The car drives well and, runs like a raped ape. We still need to do more idle tuning. Some surging/dying. We'll dial it in and should get a few more hp/tq out of it re-tuning it on a cooler day.
Collapsed lifter (only, I hope) BUILD COMPLETE
