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Exhaust valves set at .022". Valves receding?
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Author:  Eric W [ Mon Mar 31, 2008 10:36 am ]
Post subject:  Exhaust valves set at .022". Valves receding?
I checked and adjusted my valves yesterday. Found my engine likes the intake set at the usual .010" setting and exhaust valves set at .022". This got rid of the pfft pfft pfft from the exhaust pipe, leading me to believe the valves where hanging open with the .020" setting. Engine runs smoother and quiter now. Comments?
Author:  Joshie225 [ Mon Mar 31, 2008 6:23 pm ]
Post subject: 
The valve clearance has been closing up is a sign of seat recession. My exhaust valves were set to about .010" like the intakes and it didn't cause much of a miss until the engine warmed up. An extra .002" seems insignificant, but if it works for you then I say great.

Did you adjust the valves hot and running?
Author:  Rug_Trucker [ Mon Mar 31, 2008 6:38 pm ]
Post subject: 
Mine were set cold at .010 on both. That was last year 3 days before Beech Bend in April.

No problems. 6000 miles since I did that.

.020 wouldn't be a problem!
Author:  Rust collector [ Mon Mar 31, 2008 7:08 pm ]
Post subject: 
whatever it wants, I guess...
Author:  Aggressive Ted [ Mon Mar 31, 2008 8:17 pm ]
Post subject: 
Eric,

My head is a year old with new hardened exhaust seats. I am running .012 and .022 and the idle is nearly perfect, after about 10 minutes I might get a pft out of one of the cylinders, but I am at 16 degrees initial and my idle is at 650 out of gear @ 18" of vacuum. If I run the water injection for a day, it goes away for a few weeks.
Author:  Eric W [ Tue Apr 01, 2008 2:23 am ]
Post subject: 
Hmm, OK. Sounds like its no problem then. Since I've had this engine I've always set them to stock specs. Once I set them to .008" intake and .018" exhaust and didn't have a rough idle/misfire condition. I set them back because I was worried about the exhaust valves burning up.

Gotta say, after my commute today the car ran great and pulled easy up to 80, a struggle before. Thanks for the comments!
Author:  Aggressive Ted [ Tue Apr 01, 2008 10:19 am ]
Post subject: 
Eric,

At least once a week I will run it up to 90 mph. It jumps up there from cruising at 60 pretty darn quick. Doc had originally suggested the looser setting for a little more seat time to build more power so the engine would pull the tall gears and tires easier. I also see better vacuum across the rpm range. :D
Author:  Doc [ Tue Apr 01, 2008 11:58 am ]
Post subject: 
.022 lash on a stock SL6 mechanical cam is not a problem as long as you do not hear any excessive "ticking" noise.
I bet you could loosen the exhaust valves a little more and not get the ticking sound that tells you tha the lifter has missied the "lash ramp" of the cam lobe and is hitting the "flank" of the lobe before all the lash is taken-up.

As noted, lash is more of a recomendation then a set number. Racers - "Tuners" will adjust to different lash settings, depending on how they want the engine to act.
DD
Author:  LUCKY13 [ Tue Apr 01, 2008 5:51 pm ]
Post subject: 
I am running .008/.017 right now. I could "NOT" run like this before though because it would give the problems already meantioned with the pffs,pfsfs,pffs out the exhaust and power loose. Then I ran .011/.021 to keep the engine running smooth, it would not run smooth with them any tighter.


Now I have a freash head with hardened seats and new springs. Also I am running E85 which is showing to not run as hot which I feel is part of what is helping me run a tighter lash, the valves simply dont expand as much.



Jess
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