| Re: [GMCnet] Cam wear question. [message #237910] |
Wed, 29 January 2014 06:23  |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
|
Senior Member |
|
|
One other thing about this, its exactly a reason we went to roller cams. Its not hust a matter of throwing in a kit, there are many issues going to an adjustible valve train and a billet roller cam. More than I ev err thought but now that were there I'm glad we did it. There is so much stress on that cam its critical to break it in right. Rather than throwing the dice on cams break in, the $1500 plus plus to do all of whats needed is undrrstandable. After @ 200 motors out there, it seems it all works well.
Jim Bounds
-------- Original message --------
From: Harold <jal747@mac.com>
Date: 01/28/2014 6:30 PM (GMT-05:00)
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Cam wear question.
Rob, the shop I used has the same SimTest set up and procedures. They run the test until all the lifters pump oil. AFAIK, the reason for the 2000-2500 rpm break in is to insure adequate oil pressure and flow to the cam bearings and lobes. The tester provides 50psi warmed oil directly to the oil galley, so the bearings are floating for the most part, and the only issue is adequate cam lobe lubrication after all the assembly lube is wiped away.
I'm still stumped by the discoloration on all the lobes where they had not made contact with the lifters. I don't think it's pitting, but looks more like a micro build up or deposit, perhaps from the pre-assembly zinc agent they used. I added a couple more pics to the first post.
I've asked Comp Cams whether the SimTest procedure has had any history of detrimental effects with their flat tappet cams and they're looking into it.
For now, since the builder will warranty it, I'm going forward with the assembly and run it like I stole it....after I break in the cam per Comp Cams instructions that is.
W.
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Cam wear question. [message #238955 is a reply to message #237910] |
Thu, 06 February 2014 09:15  |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
|
Senior Member |
|
|
There is no doubt that a hyd roller is the way to go if you can afford it. Less friction, better reliability, and the ability to have ramp accelerations [quicker opening/closing] and valvetrain stability. Not to mention, foolproof break in lubrication. I don't think any OEM has used flat tappets for many years.
The tech is not new, was in aircraft engines prior to WWII. Even Harley Davidsons.
The biggest problem is cost. Until the OEMs were forced to by higher CAFE and emisions standards, they wouldnt spend the money.
Wheras with fords and Chevys you can take advantage of OEM roller lifters and cams we don't have that luxury for the Olds, and with low demand comes high cost of production.
Kudos for developing the system Jim B
76 Glenbrook
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
