Wiped lobe symptoms
Thread Starter
Drifting
Joined: Jun 2012
Posts: 1,990
Likes: 183
From: Port St. Lucie Fl
Wiped lobe symptoms
For those that have wiped a cam lobe what are the slightest symptoms to look for? Obviously there can be metal in the oil,running poorly but were there anything before posted above?
Melting Slicks
Joined: Oct 2010
Posts: 2,276
Likes: 337
From: "ɹǝpunuʍop", Adelaide, South Australia
i wiped #7 exhaust lobe couple years ago.
seamed to be running fine before it went sour.
previous oil change showed no sings of anything amiss.
felt like a couple of potatos had been stuffed up my exhaust pipes.
had no power under load.
here's the posts i made about it back then, https://www.corvetteforum.com/forums...r-in-72-a.html
seamed to be running fine before it went sour.
previous oil change showed no sings of anything amiss.
felt like a couple of potatos had been stuffed up my exhaust pipes.
had no power under load.
here's the posts i made about it back then, https://www.corvetteforum.com/forums...r-in-72-a.html
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
If you adjusted your lifters and now one isn't like the others, beware....
Below is a factory 45 year old cam with nylon timing gear out of my 69 427. A couple of lobes are almost a quarter inch smaller than the other worn ones but it still ran pretty good....
Below is a factory 45 year old cam with nylon timing gear out of my 69 427. A couple of lobes are almost a quarter inch smaller than the other worn ones but it still ran pretty good....
Thread Starter
Drifting
Joined: Jun 2012
Posts: 1,990
Likes: 183
From: Port St. Lucie Fl
Engine was rebuilt like 1k mi ago and changed the oil about a month ago and put about 70 ish miles since with new oil brand. I noticed a different sound in exhaust after extended idle at a light tonight and slight bog at the same time. Clears up by 1500 rpm and revs with no problems, and sounds correct.
Last edited by Kacyc3; Apr 26, 2015 at 11:34 PM.
Le Mans Master
Joined: Oct 2007
Posts: 7,454
Likes: 977
From: RI, Now Franklin/Nashville TN
Had a 73 Nova SS that wiped one lope…engine felt flat, developed a miss at idle, kept fouling the plug on the cylinder with the wiped lope…but it ran decent under power.
Le Mans Master
Joined: Aug 2005
Posts: 6,541
Likes: 1,975
From: Temple Terrace Florida
Lobe
Put a vacuum gauge on the engine to get manifold vacuum. If you have a wiped lobe, the gauge will show an erratic reading. Google engine vacuum and you will get examples on how to interpret the readings. You should be able to get a vacuum gauge kit at most auto stores for less than $20. Good luck. Jerry
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
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
"kept fouling the plug on the cylinder with the wiped lobe"
Check your plugs.
Tampa Jerry has a nice piece of advice.
"Put a vacuum gauge on the engine to get manifold vacuum."
If you have any sort of fluctuation, start looking at the valve train.
Check your plugs.Tampa Jerry has a nice piece of advice.
"Put a vacuum gauge on the engine to get manifold vacuum."
If you have any sort of fluctuation, start looking at the valve train.
Safety Car
Joined: Nov 2008
Posts: 4,368
Likes: 9
From: Colorado
Car was "chugging" when reved from idle in my garage. I just happened to pull the spark plug from the wiped lobe's cylinder and it was very fouled, oil was black and it was being used. Motor ran pretty well on 7 cylinders after some tuning, but the exhaust lobe on 7 was FLAT.
Instructor
Joined: Nov 2011
Posts: 148
Likes: 24
Kacyc3,
Was engine rebuilt with flat tappet lifters? Did you use high zinc oil? Did you follow start-up and break-in procedures (well documented on this forum)? How did the oil look that you changed at 1k?
I'd do it in this order 1) compare plugs 2) check manifold vac if you are comfortable with interpreting result 3) check lifter clearance. Loose lifters are a giveaway.
If any of the above look fishy, it is way easier to pull the intake and inspect cam/lifters than to worry for more miles and have to rebuild the whole engine.
And yes, at the time I wasn't smart enough to see the symptoms and had to do a complete $$$ rebuild. So you are asking the right questions ....
Robert
Was engine rebuilt with flat tappet lifters? Did you use high zinc oil? Did you follow start-up and break-in procedures (well documented on this forum)? How did the oil look that you changed at 1k?
I'd do it in this order 1) compare plugs 2) check manifold vac if you are comfortable with interpreting result 3) check lifter clearance. Loose lifters are a giveaway.
If any of the above look fishy, it is way easier to pull the intake and inspect cam/lifters than to worry for more miles and have to rebuild the whole engine.
And yes, at the time I wasn't smart enough to see the symptoms and had to do a complete $$$ rebuild. So you are asking the right questions ....
Robert
Thread Starter
Drifting
Joined: Jun 2012
Posts: 1,990
Likes: 183
From: Port St. Lucie Fl
Yes it has hyd. Flat tappet lifters. Yes it was broke in correctly. Oil was brown from normal use not black no alarming metal on magnetic plug. Was using valvonline vr1 racing 20 50 but made over 60.psi at idle. Couldn't find 10w30 or 40 locally so I went with another brand that is reported having 1k ppm zinc.