Cam Carrier Scored - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 02-17-2014, 11:00 AM   #21
FAB
Fab9Tuning.com
iTrader: (4)
 
FAB's Avatar
 
Join Date: Apr 2013
Posts: 942
Total Cats: 394
Default

Quote:
Originally Posted by Savington View Post
It rides on oil, just like every other bearing surface in the engine. If it's changing the surface of the journal, you have a big problem.
It should ride on a film of oil. In a perfect world. When is the last time you took a look at a bearing surface from any engine and couldn't clearly tell where the opposing material had influenced the texture of the soft bearing?

Good oil companies are praised for the way engine bearings look after having used their formula. The less visual signs of wear the better, but they do all show signs. Shear strength, proper viscosity, viscosity index over time all come into play, but "oil" and "engines" are not perfect.

I certainly can't agree that if a cam has changed the surface of a journal there is a "big problem".
FAB is offline   Reply With Quote
Old 02-17-2014, 03:33 PM   #22
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,353
Total Cats: 1,319
Default

Bearing and journal wear occurs almost exclusively at startup or during a period of oil starvation. Once oil pressure is built, there is no direct interaction between the bearing and the crankshaft (assuming no foreign objects in the oil that would cause such an interaction), and there's certainly not enough to let the camshaft somehow "seat" with the journal.

Your suggestion of a high-zinc/high-ZDDP oil is unnecessary as well, and it leads me to believe you don't actually understand what "breaks in" when you break in a camshaft. Zinc additives have almost nothing to do with cam journals and everything to do with the interaction between the cam lobe and the lifter. If the OP's cams are used and have already been broken in, there's no need for a break-in specific high-zinc oil, even if he is having the head journals and the camshaft polished to remove the damage.
Savington is offline   Reply With Quote
Old 02-17-2014, 04:02 PM   #23
FAB
Fab9Tuning.com
iTrader: (4)
 
FAB's Avatar
 
Join Date: Apr 2013
Posts: 942
Total Cats: 394
Default

Quote:
Originally Posted by Savington View Post
Bearing and journal wear occurs almost exclusively at startup or during a period of oil starvation. Once oil pressure is built, there is no direct interaction between the bearing and the crankshaft (assuming no foreign objects in the oil that would cause such an interaction), and there's certainly not enough to let the camshaft somehow "seat" with the journal.

Your suggestion of a high-zinc/high-ZDDP oil is unnecessary as well, and it leads me to believe you don't actually understand what "breaks in" when you break in a camshaft. Zinc additives have almost nothing to do with cam journals and everything to do with the interaction between the cam lobe and the lifter. If the OP's cams are used and have already been broken in, there's no need for a break-in specific high-zinc oil, even if he is having the head journals and the camshaft polished to remove the damage.
Zinc/ZDP additives are polar molecules, meaning they are attracted to steel surfaces.. allowing this film of oil to happen properly in the first place (also inside of the cam journals). I'm well aware the cam lobes and lash caps are the concerns during a "New" cam break in but that has nothing to do with his situation.

Back on topic: Zinc/ZDP is a good idea regardless of break-in, certainly contributing to the health of all journals especially if he were to attempt to clean this surface up by hand.

At any rate, sounds like the topic has moved on...

Calmdown, Best of luck with your engine.

Last edited by FAB; 02-17-2014 at 04:21 PM.
FAB is offline   Reply With Quote
Old 02-23-2014, 07:17 PM   #24
Junior Member
Thread Starter
 
Join Date: Mar 2012
Posts: 65
Total Cats: 15
Default

Found the source: Apparently an injector decided it was unhappy with it's new placement on the fuel rail (ran fine in the MK 2/2.5 frankenstein), and didn't deliver the amount of fuel it was supposed to...

This caused Cyl 3 to run lean, and pre-det, which took a chunk out of my intake valve... which then traveled down cyl 3, and took part of the oil control ring, then got mashed by the oil pump and distributed to the cam carriers.

Unfortunately I wasn't there to see the head pulled off to witness this personally, but the guys work is fairly legendary, so I'm going to take it on face value and let him sort it. Gonna cost a bit more than I was expecting though...
Calmdown is offline   Reply With Quote
Old 02-23-2014, 07:17 PM   #25
Junior Member
Thread Starter
 
Join Date: Mar 2012
Posts: 65
Total Cats: 15
Default

Found the source: Apparently an injector decided it was unhappy with it's new placement on the fuel rail (ran fine in the MK 2/2.5 frankenstein), and didn't deliver the amount of fuel it was supposed to...

This caused Cyl 3 to run lean, and pre-det, which took a chunk out of my intake valve... which then traveled down cyl 3, and took part of the oil control ring, then got mashed by the oil pump and distributed to the cam carriers.

Unfortunately I wasn't there to see the head pulled off to witness this personally, but the guys work is fairly legendary, so I'm going to take it on face value and let him sort it. Gonna cost a bit more than I was expecting though...
Calmdown is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
Toyota Pickup Engine Swap B.S. Monk Build Threads 24 12-11-2016 03:21 PM
High-lift cams, SUB, new valve job = lifter tick? Der_Idiot Engine Performance 14 09-16-2015 10:30 PM
Dumb question about crank and cam angle sensors AlwaysBroken Engine Performance 4 09-04-2015 02:35 PM
Maruha 10mm lift cams + Supertech SUB; lifter edge wear? Der_Idiot Engine Performance 12 09-03-2015 04:31 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 07:39 AM.