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I need some ideas on what to try next to stop my 416 from smoking. It's a turnkey 630HP LS3 from TSP in a '69 chevelle. Engine has 20,000km on it and has had several issues over the last few years. It came with the garbage .675EHT valvesprings (TSP 235/239 cam) which have been discontinued now and several of them broke. Being a dual spring there was no valve contact and I swapped them out for .660 PAC's and it was running beautifully.
A few thousand miles after the springs failed I failed a lifter/cam lobe...I assume the broken spring didn't do the lifter any favors which lead to the failure. I swapped the cam, lifters, oil pump, and all gaskets etc and it runs great except it smokes pretty bad. The same cylinder that the lifter failed has oil on the plug and gets oily instantly. I assumed it was valve seals but have replaced them twice with no improvement. All other cylinders are clean except for some yellowing of the plug porcelain on a few?? I did a leakdown test on the bad cylinder and it was fine ~ 5% so I wouldn't think it could be a bent valve.
Could the hammering from the failed lifter have taken out a valve guide? Where else can one hole get oil from? Cylinder walls were fine when I had the head off. I visually inspected the valves when the head was off and they looked/rolled fine so I'm baffled. I'm about to throw in the towel and start forking over money at a local shop to look at it. Anyone have any ideas?
Its hard to say, but definitely odd having only one cylinder with issues. Especially after replacing the seals multiple times. Looks like you may have to dig deeper to find the source of the problem. Have you tried contacting TSP on the subject yet?
__________________ Aaron @ Scoggin Dickey Parts Center
Email:Aaron387@sdparts.com
Phone: 1-800-456-0211 Ext: 324
It almost sounds as if that one cylinder is out-of-round.
KW
Seems odd that it would suddenly begin after failing a lifter though?
I guess the seals TSP sent could be wrong somehow but I also used them on a second cylinder that showed some weeping when I had the head off and it's fine so
Intake valve guide clearance is well beyond what a new seal can fix
If they guides are worn the seal should still be able to do it's job and wipe the oil shouldn't it? Unless the valve is moving around so much its stretching the seal out...which I'm pretty sure I would have noticed when putting those valves in (no I didn't measure because i really didn't think there was an issue when the heads were off).
TSP was of no help on the phone and just said maybe a bent valve. How bent can a valve be and still have good leakdown numbers? I did the test on a cold engine and got 5%.
Can you remove the valve cover and get a look at the rocker arm-to-valve geometry? I'm a noob to most of this stuff, but I would think that a worn guide or valve bent that badly would have some strange wear patterns where the rocker makes contact with the tip. (If there is no wear yet, you can use a Sharpie to simulate.) Before you take the rocker off to check, you could also turn the engine over slowly by hand (big wrench), and see if there is any odd behavior from the two associated valves/springs. That seems like the least amount of effort on your part to check something which could give you the clues you seek. Best of luck.
Cams over 600 lift with stock rockers causes tip contact binding
This forced scrubbing prematurely wears out valve guides specially with the broken springs you described having issues with. New seals in fucked guides is something I've done per the customer despite my best intentions. EPIC FAIL
Cams over 600 lift with stock rockers causes tip contact binding
This forced scrubbing prematurely wears out valve guides specially with the broken springs you described having issues with. New seals in fucked guides is something I've done per the customer despite my best intentions. EPIC FAIL
Interesting. I can see how that could happen but there are a lot of cars running cams over .600 with stock rockers without burning oil...I guess the loss of control with the broken springs could explain it. I'll be pulling the head this winter either way and getting the guides sorted.
Interesting. I can see how that could happen but there are a lot of cars running cams over .600 with stock rockers without burning oil...
There's a few different things going on with that statement
Few .600" plus lift cam cars end up running more than ten thousand miles before
The combination gets changed up
Also lobe lift times rocker ratio is a calculation
Rockers aren't "dead-on" ratio wise and if you dial indicate the retainer, it usually only moves .570 after push rod deflection,rocker and valve deflection,etc.
Tooley talked years ago that the GM rocker tip can only slide so far before it scrubs and digs. Ruining the valve tip and guides
There's a few different things going on with that statement
Few .600" plus lift cam cars end up running more than ten thousand miles before
The combination gets changed up
Also lobe lift times rocker ratio is a calculation
Rockers aren't "dead-on" ratio wise and if you dial indicate the retainer, it usually only moves .570 after push rod deflection,rocker and valve deflection,etc.
Tooley talked years ago that the GM rocker tip can only slide so far before it scrubs and digs. Ruining the valve tip and guides
Good point...it's likely a *bit* too big of a cam for a road trip car but it's so much fun lol! PRC heads with the machined in rocker pedestals really limit the choices for changing out rockers though. Any suggestions short of another new cam and/or heads? I'd hate to pull this head and then have more issues pop up next year.
10-31-2016, 08:31 AM
LS3 Burning Oil, Desperate! 
