Where to start valve lash
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Joined: Nov 2013
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Where to start valve lash
So after reading NUMEROUS posts from this forum and many others, including lars' procedure I'm going to be setting the lash tomorrow. As long as my crank socket gets here. But my question is this, right now my timing marks are dot to dot. Crank at 12 cam at 6. Both valves are closed on #1, my understanding is that I can do both valves now then rotate and move to #8. Am I correct?
Team Owner
Joined: May 2001
Posts: 87,376
Likes: 1,593
From: Western NY
With the engine in position of #1 cylinder at TDC, adjust:
Intakes 1, 2, 5, 7
Exhausts 1, 3, 4, 8
Turn crankshaft one full revolution clockwise, and with #6 cylinder at TDC, adjust:
Intakes 3, 4, 6, 8
Exhausts 2, 5, 6, 7
Intakes 1, 2, 5, 7
Exhausts 1, 3, 4, 8
Turn crankshaft one full revolution clockwise, and with #6 cylinder at TDC, adjust:
Intakes 3, 4, 6, 8
Exhausts 2, 5, 6, 7
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The engine is at TDC twice per cycle - you must be on TDC compression to use the companion cylinder method noted above.
http://forums.corvetteforum.com/1580029245-post6.html
If you adjusted them at TDC without knowing what stroke you were on, you adjusted them wrong.
http://forums.corvetteforum.com/1580029245-post6.html
If you adjusted them at TDC without knowing what stroke you were on, you adjusted them wrong.
Last edited by billla; Dec 5, 2013 at 12:42 PM.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Something is wrong with your engine. Cam dot at 6 and crank dot 12 = both valves on #6 will be closed for firing and vlvs on #1 will be in overlap while both #1 and #6 are at TDC.
Do u have any profile information on your car to help us help u?
cardo0
Do u have any profile information on your car to help us help u?
cardo0
Last edited by vettebuyer6369; Dec 6, 2013 at 04:09 PM. Reason: unnecessary comment removed
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Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Thread Starter
Advanced
Joined: Nov 2013
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I'll be checking the geometry before I go thru the lash procedure. Hopefully I'll be able to check ptv tonight then I can start buttoning everything up. Just in time to drive it home and park it for the next 5 months or so. Lol
Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
Dot to dot on timing chain is TDC compression stroke #6 cyl...Best to use this procedure on performance cams due to valve overlap.
http://www.centuryperformance.com/va...procedure.html
I used this method when I did my hyd roller swap.My lifters called for 1/2 turn after 0 lash per the mfg. Did you degree your cam? I also advanced the cam 4 deg for better low end torque.If your running a solid cam and aluminum heads,Crane has a tech tip:
http://www.cranecams.com/pdf-tech-tips/mech-lift.pdf
For flat tappet cams,their are now some lifters that will help lube the cam lobes...Crower cam saver lifters is one of them.I swapped in a roller and avoided all that break in,flat cam,type of oil needed hassles..
Had a friend with a BBC go through a wiped cam.Yup he followed all procedures,break in and high zinc oil.Cam lasted a few thousand miles then KAPUT!! Cam was mild,and was a complete kit .A roller swap is pricey but the gains and peace of mind are totally worth it.My 350 never ran better....Good Luck with your build...
http://www.centuryperformance.com/va...procedure.html
I used this method when I did my hyd roller swap.My lifters called for 1/2 turn after 0 lash per the mfg. Did you degree your cam? I also advanced the cam 4 deg for better low end torque.If your running a solid cam and aluminum heads,Crane has a tech tip:
http://www.cranecams.com/pdf-tech-tips/mech-lift.pdf
For flat tappet cams,their are now some lifters that will help lube the cam lobes...Crower cam saver lifters is one of them.I swapped in a roller and avoided all that break in,flat cam,type of oil needed hassles..
Had a friend with a BBC go through a wiped cam.Yup he followed all procedures,break in and high zinc oil.Cam lasted a few thousand miles then KAPUT!! Cam was mild,and was a complete kit .A roller swap is pricey but the gains and peace of mind are totally worth it.My 350 never ran better....Good Luck with your build...
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
With the dots aligned, the cam pin should be at 3:00 and the crank key should be at 2:00. This puts #6 at TDC compression and #1 at TDC exhaust.
Note that this is 180 degrees out for the distributor installation, but you can address that when the engine is being installed
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
My way too...
.
you must be a racer
QUOTE=71454Chevelle;1585602699]IMO, the best and most accurate method to adjust valves is the EOIC method:
Exhaust valve starts to open, adjust intake valve.
Intake valve starts to close, adjust exhaust valve.[/QUOTE]
the easiest and fastest way and you can start on any cylinder...no need to have the engine running either
EOI-ICE
but whatever
you must be a racer
QUOTE=71454Chevelle;1585602699]IMO, the best and most accurate method to adjust valves is the EOIC method:
Exhaust valve starts to open, adjust intake valve.
Intake valve starts to close, adjust exhaust valve.[/QUOTE]
the easiest and fastest way and you can start on any cylinder...no need to have the engine running either
EOI-ICE
but whatever
EOIC method for me