TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC V8 Engine Repair and Modifications
  New Posts New Posts RSS Feed - "white" intake valves
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

"white" intake valves

 Post Reply Post Reply
Author
Message
bikerfox View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: Aug/02/2009
Location: USA
Status: Offline
Points: 4417
Post Options Post Options   Thanks (0) Thanks(0)   Quote bikerfox Quote  Post ReplyReply Direct Link To This Post Topic: "white" intake valves
    Posted: Jan/31/2023 at 12:42am
last week, we pulled the engine and then replaced the rms,
new stock oil pan, and r and r-ed the cross ram intake, due
to a leak in the rear wall.  while the intake was out i took a
look at the intake valves through the head and they all appeared
white.  my buddies thought that the color indicated leanness,
 but i disagree, as the engine was dyno tuned and was running
quite rich before the tune. tuned to around 11.5-12.5:1 a/f.
are some valves simply white in color? wish i had taken pics!!
1969 Rebel SST (1970-1987)
1968 AMX (2005-2011)
1969 SC/Rambler (2011-2019)
1970 Javelin (2019 to ?)"Jane"
Back to Top
Trader View Drop Down
AMC Addicted
AMC Addicted


Joined: May/15/2018
Location: Ontario
Status: Offline
Points: 6755
Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jan/31/2023 at 9:59am
Do you have the dyno sheet to post?
An engine will lean out at WOT and 11.5 AF will provide maybe 5 to 10 HP more then 12:5. But 12:5 is a safer place to be.
Your lower RPM AF mixture should be higher and not go below 13.8 on a dyno starting readings @ 2500 RPM.
A lot of this has to do with fuel and altitude also.
IMO you are running lean for maximum HP and you also must know your going to be rebuilding every couple of years to maintain this.
If you want longevity over HP, then running a little rich will provide this.
White chalky residue could be fuel or fuel additives also that should be cleaned out regularly with an upper cylinder cleaner. The newer GDI intake/turbo cleaners work well.
Hard white residue is burnt on from combustion lean condition that in most cases can only be removed by abrasive blasting or solvent soaking the valves out of the engine.

Back to Top
Repsolroger View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Aug/23/2021
Location: washington
Status: Offline
Points: 367
Post Options Post Options   Thanks (0) Thanks(0)   Quote Repsolroger Quote  Post ReplyReply Direct Link To This Post Posted: Jan/31/2023 at 10:03am
I remember I used to run (trick fuel) a higher octane gas in my motorcycle and around the exhaust it would turn white instead of the black exhaust color and had a different smell....and I'm sure this doesn't help lol
1969 sst javelin restomod
Back to Top
sweatlock View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Apr/28/2014
Location: Largo, FL
Status: Offline
Points: 3285
Post Options Post Options   Thanks (0) Thanks(0)   Quote sweatlock Quote  Post ReplyReply Direct Link To This Post Posted: Jan/31/2023 at 11:48am
Lower than 14.7:1 is ‘rich’ and higher than 14.7:1 is ‘lean’, correct? 

The 14.7 refers to the amount of air vs. the amount of fuel (in this case, gasoline), as a ratio of 14.7 parts air to one part of fuel, so the less air present the richer the mixture and the more air present the leaner the mixture. 

Stoichiometric 

So why am I stating this? Because 11.5:1 is richer than 12.5:1 and 13.8:1 is leaner. 


Edited by sweatlock - Jan/31/2023 at 11:56am
Back to Top
Trader View Drop Down
AMC Addicted
AMC Addicted


Joined: May/15/2018
Location: Ontario
Status: Offline
Points: 6755
Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jan/31/2023 at 12:28pm
Yes, that is correct:
Assuming that the white residue is a lean condition, it's likely happening at cruise speed for buildup to occur.
Counter intuitive, but tuning for 12.5 over 11.5 at WOT will usually mean running richer at cruise. 13.8 @ 2500 RPM, close to cruise RPM would be rich. 

Back to Top
bikerfox View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: Aug/02/2009
Location: USA
Status: Offline
Points: 4417
Post Options Post Options   Thanks (0) Thanks(0)   Quote bikerfox Quote  Post ReplyReply Direct Link To This Post Posted: Jan/31/2023 at 10:56pm
thanks for the replies.  i'll find the dyno sheets and post them shortly.
1969 Rebel SST (1970-1987)
1968 AMX (2005-2011)
1969 SC/Rambler (2011-2019)
1970 Javelin (2019 to ?)"Jane"
Back to Top
BassBoat View Drop Down
AMC Addicted
AMC Addicted


Joined: Aug/29/2008
Status: Offline
Points: 1713
Post Options Post Options   Thanks (0) Thanks(0)   Quote BassBoat Quote  Post ReplyReply Direct Link To This Post Posted: Feb/01/2023 at 3:32pm
I agree with the guy that told you white is lean.  maybe you had a vacuum leak or tuning problem after the dyno tuning.  12.5 will probably make peak power on a dyno.  11.8 which is "too" rich will give a quicker time at the dragstrip.  



Edited by BassBoat - Feb/02/2023 at 10:51am
Back to Top
FSJunkie View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jan/09/2011
Location: Flagstaff, AZ
Status: Offline
Points: 4741
Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Feb/02/2023 at 1:37am
Fuel mixture has little influence on intake valve color in my experience. It does make a world of difference on exhaust valve color, however. 

White intake valves could be deposits from additives in the fuel or from a form of corrosion. Aluminum oxide is a white powder. The valves themselves shouldn't corrode, but I suppose that corrosion inside an aluminum intake manifold could leave oxide deposits on the valves. 

Intake valves usually end up a disgusting gooey brown color from the oil vapors drawn in by the PCV... 
1955 Packard
1966 Marlin
1972 Wagoneer
1973 Ambassador
1977 Hornet
1982 Concord D/L
1984 Eagle Limited
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.094 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or