LT1 Valve drop?
Thread Starter
Instructor
Joined: Jan 2017
Posts: 146
Likes: 9
From: Mobile, Alabama
LT1 Valve drop?
Hello all, I bought a 2016 M7 Z51 a few months ago and I am planning on building it over the next year or two. Goal is to make 850-900whp with a V3TI. Car is currently stock.
I've been trying to read up on the LT1 heads but there are not many forum posts on them. From what I've learned, the heads on the LT1 have almost the exact same issue as the LS7 heads with dropping valve seats/valves.
With that being said, what good options are there for aftermarket LT1 heads that are affordable? Not looking for a set of 4-5k heads.
My first round of mods will be GPI drop in rotating assembling, BTR stage 3 cam, head work, and DSX flex fuel kit, then when I have the $$ do the V3TI and MSD/LT5 TB and fueling.
I've been trying to read up on the LT1 heads but there are not many forum posts on them. From what I've learned, the heads on the LT1 have almost the exact same issue as the LS7 heads with dropping valve seats/valves.
With that being said, what good options are there for aftermarket LT1 heads that are affordable? Not looking for a set of 4-5k heads.
My first round of mods will be GPI drop in rotating assembling, BTR stage 3 cam, head work, and DSX flex fuel kit, then when I have the $$ do the V3TI and MSD/LT5 TB and fueling.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Hello all, I bought a 2016 M7 Z51 a few months ago and I am planning on building it over the next year or two. Goal is to make 850-900whp with a V3TI. Car is currently stock.
I've been trying to read up on the LT1 heads but there are not many forum posts on them. From what I've learned, the heads on the LT1 have almost the exact same issue as the LS7 heads with dropping valve seats/valves.
With that being said, what good options are there for aftermarket LT1 heads that are affordable? Not looking for a set of 4-5k heads.
My first round of mods will be GPI drop in rotating assembling, BTR stage 3 cam, head work, and DSX flex fuel kit, then when I have the $$ do the V3TI and MSD/LT5 TB and fueling.
I've been trying to read up on the LT1 heads but there are not many forum posts on them. From what I've learned, the heads on the LT1 have almost the exact same issue as the LS7 heads with dropping valve seats/valves.
With that being said, what good options are there for aftermarket LT1 heads that are affordable? Not looking for a set of 4-5k heads.
My first round of mods will be GPI drop in rotating assembling, BTR stage 3 cam, head work, and DSX flex fuel kit, then when I have the $$ do the V3TI and MSD/LT5 TB and fueling.
if the heads did have issues, the internet would light up, just like it did with LS7.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 146
Likes: 9
From: Mobile, Alabama
LT1s do not have the same issue as the LS7 which was about the valve guides (hence the “wiggle test”). The only LT1 issue has been broken valve springs. Even that is few and far between when you consider the 10s of thousands of cars out there. You’ll be replacing the factory springs due to the cam you’ve selected.
if the heads did have issues, the internet would light up, just like it did with LS7.
if the heads did have issues, the internet would light up, just like it did with LS7.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Not an LS7 type failure and without knowing hp levels and rpm, who knows the cause.
Regardless, if I was going to run 700+hp, I sure wouldn’t skimp on the heads. Fast, cheap, reliable….pick any two.
Regardless, if I was going to run 700+hp, I sure wouldn’t skimp on the heads. Fast, cheap, reliable….pick any two.
Racer
Joined: May 2014
Posts: 353
Likes: 23
From: Fernandina Beach, FL
I saw that post too. It’s the first I have heard of it but he’s a big name with the LT1 so I’m sure he’s seen it. As mentioned, no idea what conditions these engines were run under. Hopefully it’s not a huge deal as I just finished getting my cam/heads done with stock valves.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 146
Likes: 9
From: Mobile, Alabama
I saw that post too. It’s the first I have heard of it but he’s a big name with the LT1 so I’m sure he’s seen it. As mentioned, no idea what conditions these engines were run under. Hopefully it’s not a huge deal as I just finished getting my cam/heads done with stock valves.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 146
Likes: 9
From: Mobile, Alabama
I saw that post too. It’s the first I have heard of it but he’s a big name with the LT1 so I’m sure he’s seen it. As mentioned, no idea what conditions these engines were run under. Hopefully it’s not a huge deal as I just finished getting my cam/heads done with stock valves.
JW (big ctsv tuner now focusing on LT) also ran into a similar issue.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
....and it clearly says when porting the heads.
As soon as you start messing with the factory stuff like that, all bets are off. If you use the factory heads "as is" with the exception of the correct valve springs, it's exceedingly rare to find a problem. There are probably 100k+ Gen V LT1s out there running around. If there were head problems like the LS7, you'd know about it. The LS7 issues were on Stock heads on Stock motors.
You've already decided that there's an issue. As such, have the heads worked.
Guess what. Here's what's in mine.....
As soon as you start messing with the factory stuff like that, all bets are off. If you use the factory heads "as is" with the exception of the correct valve springs, it's exceedingly rare to find a problem. There are probably 100k+ Gen V LT1s out there running around. If there were head problems like the LS7, you'd know about it. The LS7 issues were on Stock heads on Stock motors.
You've already decided that there's an issue. As such, have the heads worked.
Guess what. Here's what's in mine.....
FED LT1 Ported Cylinder Heads
CNC Port, CNC Valve Job
Hand Blend, Surface 0.010"
Hand Blend, Surface 0.010"
Del-West Titanium Intake Valves
Manley Stainless Exhaust Valves
Bronze Valve Guides
.660 Dual LSX Spring Kit w/ Titanium Retainers.
I'm around 560 at the wheels.Manley Stainless Exhaust Valves
Bronze Valve Guides
.660 Dual LSX Spring Kit w/ Titanium Retainers.
Le Mans Master
Joined: Oct 2014
Posts: 8,673
Likes: 2,728
From: Atlanta GA
LT1s do not have the same issue as the LS7 which was about the valve guides (hence the “wiggle test”). The only LT1 issue has been broken valve springs. Even that is few and far between when you consider the 10s of thousands of cars out there. You’ll be replacing the factory springs due to the cam you’ve selected.
if the heads did have issues, the internet would light up, just like it did with LS7.
if the heads did have issues, the internet would light up, just like it did with LS7.
Dave
Safety Car
Joined: Nov 2011
Posts: 3,715
Likes: 343
From: Norman OK
Brett (Pray Porting) has said that it is a combination of the increased RPM above the stock RPM limit along with the cam lobe being very aggressive on some cams causing the valves to jump and slam into the valve seats which eventually can cause the issues with chipping the seats.
Administrator
Joined: Mar 2001
Posts: 368,360
Likes: 24,786
From: In a parallel universe. Currently own 2014 Stingray Coupe.
C7 of the Year - Modified Finalist 2021
MO Events Coordinator
St. Jude Co-Organizer
St. Jude Donor '03 thru '26
NCM Sinkhole Donor
CI 5, 8 & 11 Veteran
Sure as heck hope stock LT1 heads rarely have valve issues - that would be a real PITA.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 146
Likes: 9
From: Mobile, Alabama
....and it clearly says when porting the heads.
As soon as you start messing with the factory stuff like that, all bets are off. If you use the factory heads "as is" with the exception of the correct valve springs, it's exceedingly rare to find a problem. There are probably 100k+ Gen V LT1s out there running around. If there were head problems like the LS7, you'd know about it. The LS7 issues were on Stock heads on Stock motors.
You've already decided that there's an issue. As such, have the heads worked.
Guess what. Here's what's in mine.....
As soon as you start messing with the factory stuff like that, all bets are off. If you use the factory heads "as is" with the exception of the correct valve springs, it's exceedingly rare to find a problem. There are probably 100k+ Gen V LT1s out there running around. If there were head problems like the LS7, you'd know about it. The LS7 issues were on Stock heads on Stock motors.
You've already decided that there's an issue. As such, have the heads worked.
Guess what. Here's what's in mine.....
FED LT1 Ported Cylinder Heads
CNC Port, CNC Valve Job
Hand Blend, Surface 0.010"
Hand Blend, Surface 0.010"
Del-West Titanium Intake Valves
Manley Stainless Exhaust Valves
Bronze Valve Guides
.660 Dual LSX Spring Kit w/ Titanium Retainers.
I'm around 560 at the wheels.Manley Stainless Exhaust Valves
Bronze Valve Guides
.660 Dual LSX Spring Kit w/ Titanium Retainers.
Last edited by CorbinC5; Apr 2, 2024 at 03:46 PM.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 146
Likes: 9
From: Mobile, Alabama
Drifting
Joined: Apr 2020
Posts: 1,357
Likes: 558
From: MN
LT1s do not have the same issue as the LS7 which was about the valve guides (hence the “wiggle test”). The only LT1 issue has been broken valve springs. Even that is few and far between when you consider the 10s of thousands of cars out there. You’ll be replacing the factory springs due to the cam you’ve selected.
if the heads did have issues, the internet would light up, just like it did with LS7.
if the heads did have issues, the internet would light up, just like it did with LS7.
6th Gear
Joined: Sep 2014
Posts: 6
Likes: 0
Bumping this thread since my LT1 dropped an intake valve about 2 weeks ago when I was at VIR.
As I drove onto the back straight, I shifted from 3 to 4 and heard pop. Smoke out the back, put it in neutral, reduced power and flashing engine light, then the motor died.
My mechanic found my #2 intake valve dropped, the crunched up remains of the valve stem were in my throttle body! Bone stock engine, approximately 36,000 miles on a 2014 Z51. Most of the failures I have read about dropping valves seem to be on earlier LT1s.
Any chance they made some improvements over the years to address this? Most likely going with a new long block from GM to get the car running again. If not, is there anything that can be done other than aftermarket heads? Take off the valve covers and manually inspect every valve and valve spring periodically?
As I drove onto the back straight, I shifted from 3 to 4 and heard pop. Smoke out the back, put it in neutral, reduced power and flashing engine light, then the motor died.
My mechanic found my #2 intake valve dropped, the crunched up remains of the valve stem were in my throttle body! Bone stock engine, approximately 36,000 miles on a 2014 Z51. Most of the failures I have read about dropping valves seem to be on earlier LT1s.
Any chance they made some improvements over the years to address this? Most likely going with a new long block from GM to get the car running again. If not, is there anything that can be done other than aftermarket heads? Take off the valve covers and manually inspect every valve and valve spring periodically?
Le Mans Master
Joined: Oct 2014
Posts: 8,673
Likes: 2,728
From: Atlanta GA
Bumping this thread since my LT1 dropped an intake valve about 2 weeks ago when I was at VIR.
As I drove onto the back straight, I shifted from 3 to 4 and heard pop. Smoke out the back, put it in neutral, reduced power and flashing engine light, then the motor died.
My mechanic found my #2 intake valve dropped, the crunched up remains of the valve stem were in my throttle body! Bone stock engine, approximately 36,000 miles on a 2014 Z51. Most of the failures I have read about dropping valves seem to be on earlier LT1s.
Any chance they made some improvements over the years to address this? Most likely going with a new long block from GM to get the car running again. If not, is there anything that can be done other than aftermarket heads? Take off the valve covers and manually inspect every valve and valve spring periodically?
As I drove onto the back straight, I shifted from 3 to 4 and heard pop. Smoke out the back, put it in neutral, reduced power and flashing engine light, then the motor died.
My mechanic found my #2 intake valve dropped, the crunched up remains of the valve stem were in my throttle body! Bone stock engine, approximately 36,000 miles on a 2014 Z51. Most of the failures I have read about dropping valves seem to be on earlier LT1s.
Any chance they made some improvements over the years to address this? Most likely going with a new long block from GM to get the car running again. If not, is there anything that can be done other than aftermarket heads? Take off the valve covers and manually inspect every valve and valve spring periodically?
It's my understanding that the earlier LT1's including mine had yellow springs and that they were changed to blue springs which I have now . Not sure if the blue springs are any better as you still hear about LT1 motors breaking springs
Dave
Instructor
Joined: Dec 2016
Posts: 160
Likes: 49
From: Upstate NY
So it's my understanding that in the early days of the LT1/4 that the cams available at the time had in essence LS lobe profiles that were causing the valve to bounce on the seat.
Thus hammering the seats, leading to dropped seats. Once this was understood and the spintron data was analyzed LT friendly lobes were created and the issue is all but gone today.
Shoe
Thus hammering the seats, leading to dropped seats. Once this was understood and the spintron data was analyzed LT friendly lobes were created and the issue is all but gone today.
Shoe
Le Mans Master
Joined: Oct 2014
Posts: 8,673
Likes: 2,728
From: Atlanta GA
So it's my understanding that in the early days of the LT1/4 that the cams available at the time had in essence LS lobe profiles that were causing the valve to bounce on the seat.
Thus hammering the seats, leading to dropped seats. Once this was understood and the spintron data was analyzed LT friendly lobes were created and the issue is all but gone today.
Shoe
Thus hammering the seats, leading to dropped seats. Once this was understood and the spintron data was analyzed LT friendly lobes were created and the issue is all but gone today.
Shoe
The spring breakage was addressed when they changed to the blue springs , but it remains to be seen ....
h
As far as the valve seat issues this is the first time I have heard that and I am not sure what an LT friendly lobe is .... I have not heard of any changes being made to the stock cam profile
Do you have a link to this .....
Dave