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914World.com _ 914World Garage _ Valve Train mods
Posted by: jeffdon Aug 1 2012, 01:45 PM
Getting set to drop the engine so I can have a sparkplug hole repaired.
While out, I am considering finally going through my valve train geometry, cutting custom pushrods, and going to swivel feet adjusters.
Does anyone have experience with the 9mm Rhino feet from CB performance? They are WAY less expensive than Porsche units, and would negate having to switch to 1.7 rockers.
Are they good, or just Chinese junk?
Posted by: The Cabinetmaker Aug 1 2012, 01:52 PM
I have not used the chinese stuff, but the 911 adjusters must use the 1.7 rockers. The 2.0L rockers have a bigger adjuster thread.
I really don't see you have anything to gain with a stock engine.
Posted by: jeffdon Aug 1 2012, 02:00 PM
I have not used the chinese stuff, but the 911 adjusters must use the 1.7 rockers. The 2.0L rockers have a bigger adjuster thread.
I really don't see you have anything to gain with a stock engine.
Its not stock. 2056 with webers and a webcam #494.
Posted by: The Cabinetmaker Aug 1 2012, 02:07 PM
Well nevermind then! My 2056 has all the valve train upgrades but the heavey duty springs. Even with stock springs the rev in the upper limits is smoother. I like adjusting the valves at zero lash with the chromemoly pusrods.
Posted by: jeffdon Aug 1 2012, 02:10 PM
Well nevermind then! My 2056 has all the valve train upgrades but the heavey duty springs. Even with stock springs the rev in the upper limits is smoother. I like adjusting the valves at zero lash with the chromemoly pusrods.
Good to know. What procedure are you using to measure zero lash?
Posted by: McMark Aug 1 2012, 02:43 PM
They way I think of it:
Porsche builds components that live up the their long reputation of quality.
CBPerformance builds (rather RESELLS) components that meet a price point. Quality isn't the first priority.
So if your first priority is cost, buy the CBPerformance pieces. If your first priority is quality and long life, shell out for the Porsche components.
Posted by: jeffdon Aug 1 2012, 02:47 PM
They way I think of it:
Porsche builds components that live up the their long reputation of quality.
CBPerformance builds (rather RESELLS) components that meet a price point. Quality isn't the first priority.
So if your first priority is cost, buy the CBPerformance pieces. If your first priority is quality and long life, shell out for the Porsche components.
Good point, Mark. What would your take be on used 911 adjusters if I can find them?
Posted by: Katmanken Aug 1 2012, 02:50 PM
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Posted by: McMark Aug 1 2012, 03:33 PM
I don't think I've heard of OE swivels going bad. New would make me feel better. But used OE would be a good second place unless someone else chimes in with stories of swivel failure.
Posted by: Valy Aug 1 2012, 03:44 PM
I would evaluate the state of the cam before doing any changes. The 911 adjusters only at high lift. If your cam is worn out than you better not add heavier lifters. Also old valve springs won't like the heavier lifters as well.
Posted by: jeffdon Aug 1 2012, 08:26 PM
I would evaluate the state of the cam before doing any changes. The 911 adjusters only at high lift. If your cam is worn out than you better not add heavier lifters. Also old valve springs won't like the heavier lifters as well.
The cam is higher lift than stock....springs are stock....really confused now.
Posted by: McMark Aug 1 2012, 11:47 PM
The swivel foot adjusters are hardly heavier than stock. And if you were to cut off the excess thread they would probably be lighter. Not that I'd promote that.
Posted by: euro911 Aug 2 2012, 12:47 AM
We're also running a 2056, Mahle jugs, Keith Black pistons, Raby spec'd heads with 44/38mm S/S valves, 9.0:1 C/R, 9580 cam, chromemoly push rods, 911 swivels and clearanced 1.7L rocker arms.
Just a suggestion, but if you're having one spark plug hole repaired, it's a good idea to have steel inserts installed in all four holes ... no more stripped or cross-thread issues 
Posted by: jeffdon Aug 2 2012, 07:34 AM
We're also running a 2056, Mahle jugs, Keith Black pistons, Raby spec'd heads with 44/38mm S/S valves, 9.0:1 C/R, 9580 cam, chromemoly push rods, 911 swivels and clearanced 1.7L rocker arms.
Just a suggestion, but if you're having one spark plug hole repaired, it's a good idea to have steel inserts installed in all four holes ... no more stripped or cross-thread issues
Considering this, but have heard somewhere that the 2.0 heads have less heat dissipating ability around the plugs, which is further diminished with the inserts. But I am thinking, really, how much material could you loose?
Posted by: Valy Aug 2 2012, 08:48 AM
I would evaluate the state of the cam before doing any changes. The 911 adjusters only at high lift. If your cam is worn out than you better not add heavier lifters. Also old valve springs won't like the heavier lifters as well.
The cam is higher lift than stock....springs are stock....really confused now.
The cam HAD higher lift that stock when new. You should check how much is left of that lift.
Not implying that your cam is gone but I've seen flat cams on low mileage engines.
Posted by: jeffdon Aug 2 2012, 09:00 AM
I would evaluate the state of the cam before doing any changes. The 911 adjusters only at high lift. If your cam is worn out than you better not add heavier lifters. Also old valve springs won't like the heavier lifters as well.
The cam is higher lift than stock....springs are stock....really confused now.
The cam HAD higher lift that stock when new. You should check how much is left of that lift.
Not implying that your cam is gone but I've seen flat cams on low mileage engines.
After only 8k miles? It would be scary to see a significant reduction in lift after only 8k.
Posted by: Racer Chris Aug 2 2012, 11:02 AM
Its even worse when the cam goes flat in less than 80 miles. 
It happens.
Posted by: jeffdon Aug 2 2012, 12:10 PM
Its even worse when the cam goes flat in less than 80 miles.
It happens.
The cam and lifters are new, the springs are standard, running brad penn oil, so unless I got a flawed cam, what would cause such rapid wear?
Posted by: euro911 Aug 2 2012, 12:16 PM
Posted by: Racer Chris Aug 2 2012, 12:27 PM
Its even worse when the cam goes flat in less than 80 miles.
It happens.
The cam and lifters are new, the springs are standard, running brad penn oil, so unless I got a flawed cam, what would cause such rapid wear?
In the case I mentioned, it was a combination of high spring pressures and improperly hardened lifters against a fairly high lift cam.
If you got 8K miles already and you're using Brad Penn, I doubt you have a flat cam.
Posted by: Valy Aug 2 2012, 01:14 PM
Its even worse when the cam goes flat in less than 80 miles.
It happens.
The cam and lifters are new, the springs are standard, running brad penn oil, so unless I got a flawed cam, what would cause such rapid wear?
It doesn't have to be flat. I'm not trying to scare you
Just check the lift with a dialmeter on the rockers. It's very simple.
The point is that it's easier to check before you get into all the trouble of replacing the valve train. And since the push-rods are custom-cut for your engine, it will be a waste of money to cut them for a worn-out cam.
A lot of the cam wear happens in the initial brake-in period but there is permanent wear all the time. I've seen a webcam out of a ~10K engine that had 2mm shaved off the lobes without any apparent abuse to the engine.
Posted by: jeffdon Aug 2 2012, 01:38 PM
Its even worse when the cam goes flat in less than 80 miles.
It happens.
The cam and lifters are new, the springs are standard, running brad penn oil, so unless I got a flawed cam, what would cause such rapid wear?
It doesn't have to be flat. I'm not trying to scare you
Just check the lift with a dialmeter on the rockers. It's very simple.
The point is that it's easier to check before you get into all the trouble of replacing the valve train. And since the push-rods are custom-cut for your engine, it will be a waste of money to cut them for a worn-out cam.
A lot of the cam wear happens in the initial brake-in period but there is permanent wear all the time. I've seen a webcam out of a ~10K engine that had 2mm shaved off the lobes without any apparent abuse to the engine.
Webcam making inferior cams?
Posted by: jeffdon Aug 2 2012, 01:39 PM
THANKS!
Yep, thats what I did.
Posted by: Valy Aug 2 2012, 02:24 PM
Its even worse when the cam goes flat in less than 80 miles.
It happens.
The cam and lifters are new, the springs are standard, running brad penn oil, so unless I got a flawed cam, what would cause such rapid wear?
It doesn't have to be flat. I'm not trying to scare you
Just check the lift with a dialmeter on the rockers. It's very simple.
The point is that it's easier to check before you get into all the trouble of replacing the valve train. And since the push-rods are custom-cut for your engine, it will be a waste of money to cut them for a worn-out cam.
A lot of the cam wear happens in the initial brake-in period but there is permanent wear all the time. I've seen a webcam out of a ~10K engine that had 2mm shaved off the lobes without any apparent abuse to the engine.
Webcam making inferior cams?
No, that's not the point. It can happen to any cam but it so happened that the one I've witnessed was a webcam. I still have it if you want to see it.
My new cam is a webcam as well so it's not that I'm saying that webcams are bad.
The engine was still running strong with that cam so you never know until you check.
Posted by: McMark Aug 2 2012, 02:34 PM
Jeffdon, if your cam was losing lift, you'd notice that you had to adjust the valves every time to checked them. Had any adjusters that were seriously loose?
Posted by: jeffdon Aug 2 2012, 02:35 PM
Jeffdon, if your cam was losing lift, you'd notice that you had to adjust the valves every time to checked them. Had any adjusters that were seriously loose?
No. Matter of fact, only about half needed any adjust at all last time. Minor at that.
Posted by: Valy Aug 2 2012, 02:36 PM
Jeffdon, if your cam was losing lift, you'd notice that you had to adjust the valves every time to checked them. Had any adjusters that were seriously loose?
Sorry Mark, you are wrong this time.
The cam has almost no wear at the low point, where the valve adjustment is done. All the wear is on the lobe and there is no way to see that just from valve adjustment. You have to measure it.
Posted by: McMark Aug 2 2012, 02:46 PM
My point is that you don't lose 2mm off your cam lobe and not notice something's wrong.
Posted by: HAM Inc Aug 2 2012, 06:24 PM
Mark's right. When the cam wears so does the lifter, usually (but not always) even more than the cam.
The swivel screws are a great upgrade even for stock cams. The reduction in side loading of the valve combined with the reduced friction at the stem/adjuster interface is very beneficial. Valve guides last longer and so do the valves.
Use genuine Porsche adjusters if you plan to keep the car and only want to do it once.
The swivel screws do weigh a bit more than the stock adjusters, but the material you remove when the rockers are clearanced for the screws makes up for it.
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