Rocker shaft to rocker arm clearance, Is there a spec? |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Rocker shaft to rocker arm clearance, Is there a spec? |
Woody |
Jul 30 2013, 07:37 AM
Post
#1
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
This is on a /4 2056. I've been chasing a noise that I believe is coming from the top end. It only occurs at idle and will completely disappear right off idle. It sounds like really loud valve clatter. Valves were recently adjusted and were not too far out of spec, Maybe a little bit tight. Noise was present before the valve adjust. On startup it is pretty bad, as the oil heats up it gets worse, but when the engine is at full operating temp after a 30 minute drive the noise is gone. I pulled the rockers and shafts to inspect for wear. The rocker shafts show some wear visually and measure at or just below spec at 19.94mm or .785". Haynes shows the spec at 19.95-19.97 mm. The shafts are not ovaled. The rocker arms measure out at 20.02 inside diameter or .788" and also are not ovaled. Does anyone know what the clearance is supposed to be?
|
Woody |
Jul 30 2013, 03:31 PM
Post
#2
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
|
ChrisFoley |
Jul 30 2013, 06:08 PM
Post
#3
|
I am Tangerine Racing Group: Members Posts: 7,935 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
ALL the load is on one side of the shafts and the rocker bores.
If the shafts aren't scored and the dia difference is only .003 I can't see how there would be any problem. |
Woody |
Jul 30 2013, 06:09 PM
Post
#4
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
There is some minor scoring but they still measure even across the shaft.
|
Woody |
Jul 31 2013, 12:23 PM
Post
#5
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
|
rick_cv |
Jul 31 2013, 12:32 PM
Post
#6
|
Newbie Group: Members Posts: 33 Joined: 3-March 09 From: PNW Member No.: 10,125 Region Association: Pacific Northwest |
Which pistons did you use for your 2056? Forged? Do a search for piston slap with forged pistons during warm up. Seems to be a common issue due to differing expansion rates between cylinders and piston.
|
Woody |
Jul 31 2013, 12:35 PM
Post
#7
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
This is a new noise though. It became noticeable a couple months ago. I've had the engine for a few years. I wouldn't think piston slap would all of a sudden show up.
|
Woody |
Jul 31 2013, 02:19 PM
Post
#8
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
Im gonna try some new adjusters. A couple of mine are pitted pretty bad.
|
r_towle |
Jul 31 2013, 04:00 PM
Post
#9
|
Custom Member Group: Members Posts: 24,591 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Solid spacers or are you still using the springs?
|
Woody |
Jul 31 2013, 05:13 PM
Post
#10
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
Springs for now.
|
r_towle |
Jul 31 2013, 05:26 PM
Post
#11
|
Custom Member Group: Members Posts: 24,591 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Pushrods tips?
Lifters? Think about solid spacers while you are doing this...it helps keep the valve train consistent. |
Woody |
Jul 31 2013, 05:29 PM
Post
#12
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
Just original adjusters. I'm going to replace the adjusters, rockers, shafts, and springs to see if it goes away. If it doesn't I'll take it apart. I built this engine when I was new to 914s.
|
Woody |
Jul 31 2013, 05:30 PM
Post
#13
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
Pushrods look good. Lifters are webcam. Valve lash has been consistent and hasn't changed much.
|
r_towle |
Jul 31 2013, 05:37 PM
Post
#14
|
Custom Member Group: Members Posts: 24,591 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
solid spaces might be the right thing to do at this specific moment...kinda a pita to take it all apart again...and they are cheap.
rich |
r_towle |
Jul 31 2013, 05:38 PM
Post
#15
|
Custom Member Group: Members Posts: 24,591 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
do you have swivel foot adjusters or stock solid ones?
|
Woody |
Jul 31 2013, 05:40 PM
Post
#16
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
Solid adjusters. Who sells the solid spacers?
|
r_towle |
Jul 31 2013, 05:42 PM
Post
#17
|
Custom Member Group: Members Posts: 24,591 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
|
Woody |
Jul 31 2013, 05:44 PM
Post
#18
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
Thanks Rich. Gonna have to try that.
|
r_towle |
Jul 31 2013, 05:47 PM
Post
#19
|
Custom Member Group: Members Posts: 24,591 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
I think of it like this.
You never really know what the rocker is going to do with springs. You reduce that variable quite a bit when you use solid spacers... Then you are getting exactly what you expect from the whole valve train. Otherwise, with the rocker having the ability to move...you may not get the lift expected on each cylinder and that could make things run less than optimal. For what, 4 bucks each...why not. The rest of the parts you can get fairly cheap also.. New shafts, 16 bucks....just do that...no hesitation in my mind. Rich |
Woody |
Jul 31 2013, 05:50 PM
Post
#20
|
Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
I need the car together for Saturday. I'll probably pull it back apart after this weekend.
|
Lo-Fi Version | Time is now: 10th June 2024 - 09:28 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |