How can you tell if you have flat cam lobes?, Strange lash issue |
|
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. |
|
How can you tell if you have flat cam lobes?, Strange lash issue |
tornik550 |
Jun 15 2012, 02:27 PM
Post
#1
|
Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
I am paranoid of developing flat can lobes on my recent engine rebuild. I am paranoid cause I have heard so much crap about the cam that I used- scat c45. I am asking this more for curiosity sake. I had a strange issue but I am certain it's unrelated. I set my valves on cyl 1 to 0 lash (chromoly pushrods). I did that at tdc for that cyl. Te intake and exhaust valves. Seem to lift normally. The issue is that at a different point in the cycle (other than tdc or full lift) the valves are very loose. The valves go back to zero lash at TDC. The compression is actually about 5 points better on that cylander. I think it's possible that the rocker shaft bolts may have loosened a bit, however I've already removed them. It doesn't sound like a flat lobe to me.
|
toolguy |
Jun 15 2012, 04:08 PM
Post
#2
|
Senior Member Group: Members Posts: 1,270 Joined: 2-April 11 From: San Diego / El Cajon Member No.: 12,889 Region Association: Southern California |
you're suppose to be adjusting the lash on the back side of the cam lobe, i.e. the lowest point or the base circle, when the piston is at the top of the compression cycle and the distributor is pointing to that cylinders wire. . . so start by looking where the rotor is pointing in relationship to the timing mark.
When a cam goes 'flat' it is from excessive wear on the top of the lobe or when a valve is fully open. . . you can't really feel or see that the lobe is going flat other than maybe noticing the valve doesn't open as far as the others. . / / / . . . If the valve gets loser after you adjust it, then either your weren't positioned on the back of the cam in the first place. . OR the cam is not concentric on the base circle, meaning it was improperly ground in the first place. . |
Lo-Fi Version | Time is now: 9th June 2024 - 04:43 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 ... |