Lash adjustment

Old 07-18-2009, 07:30 AM
  #1  
heshtesh
Member
MASTER JOURNEYMAN
Thread Starter
 
Join Date: Feb 2008
Posts: 45
Default Lash adjustment

Getting ready to set lash on my first solid roller the mfg. recommends .021 int. side .023 exh. side hot. Should i allow a couple thou extra clearance due to the fact my initial set-up is cold. I figure later i can do the math and calculate the expansion of the alum heads so i can do them cold.
heshtesh is offline  
Old 07-18-2009, 08:47 AM
  #2  
curtisreed
Senior Member
RACING JUNKIE
 
curtisreed's Avatar
 
Join Date: Feb 2004
Location: KIEFER, OK.
Posts: 1,312
Default

You will pick up about .005-.006 after the motor heats up. If you need .021 hot set them at .015-.016 and .017-.018 cold.

That is with iron block and aluminum heads.

Curtis
curtisreed is offline  
Old 07-19-2009, 07:50 AM
  #3  
heshtesh
Member
MASTER JOURNEYMAN
Thread Starter
 
Join Date: Feb 2008
Posts: 45
Default

Curtis: Thanks for the info, i'm surpised they expand that much but i will use your info for my starting point. Again Thank You.
heshtesh is offline  
Old 07-19-2009, 08:05 AM
  #4  
russ67chevelle
Senior Member
EXPERT BUILDER
 
Join Date: Jan 2005
Posts: 336
Default

my big chevy stuff requires .004 to .005 less clearance cold.most were fine with .004 tighter,but about 2 per side needed to be slightly tighter when checked hot
russ67chevelle is offline  
Old 07-19-2009, 09:11 PM
  #5  
chevyart
Senior Member
MASTER BUILDER
 
Join Date: Mar 2008
Posts: 173
Default valve lash

i have sbc iron block and iron heads. i set my valve cold just the opposite. i set them looser and when they heat up they tighten (example) i set them cold around 26 to get about 22 when hot. is this correct chevy art
chevyart is offline  
Old 07-19-2009, 09:37 PM
  #6  
Tod74
Senior Member
RACING JUNKIE
 
Join Date: Sep 2007
Posts: 4,137
Default

Originally Posted by doorracer
You will pick up about .005-.006 after the motor heats up. If you need .021 hot set them at .015-.016 and .017-.018 cold.

That is with iron block and aluminum heads.

Curtis
X2

I have a Big Chevy with iron block/aluminum heads and mine opens up about .006 when it heats up. What I do is set them about .006 tight to get the thing started, then get it up to operating temp and check them and see how much they opened up.That way you know how much and then you can do the math and just set them cold every time. JUST MY OPINION
Tod74 is offline  
Old 07-20-2009, 04:06 AM
  #7  
curtisreed
Senior Member
RACING JUNKIE
 
curtisreed's Avatar
 
Join Date: Feb 2004
Location: KIEFER, OK.
Posts: 1,312
Default

heshtesh, one other thing I would mention is the way I set the lash. If you are shooting for .020 setting, (arbitrary number), I use a .019 and .021 feeler guauge as a go and no-go. .019 goes easy and .021 will not go, gets you right on .020. I guess I have been a machinist to long to just set it with the size gauge I am shooting for.

Curtis
curtisreed is offline  
Old 07-20-2009, 05:01 AM
  #8  
TS1955
Senior Member
DYNO OPERATOR
 
Join Date: Aug 2007
Location: Lost Creek, WV
Posts: 533
Default

There was some discussion on this subject a little while ago. So the last time I adjust the valves on my motor, ( small blocl chevy, cast block & aluminum heads) I set them .006 tight cold. Warmed the engine up to 200 degrees, pulled the rocker covers and the lash was right on the money.

TS1955
TS1955 is offline  
Old 07-20-2009, 07:58 AM
  #9  
CamBirdRacing
Senior Member
DYNO OPERATOR
 
Join Date: Feb 2009
Posts: 510
Default

Originally Posted by doorracer
heshtesh, one other thing I would mention is the way I set the lash. If you are shooting for .020 setting, (arbitrary number), I use a .019 and .021 feeler guauge as a go and no-go. .019 goes easy and .021 will not go, gets you right on .020. I guess I have been a machinist to long to just set it with the size gauge I am shooting for.

Curtis

KD tools make s go-nogo feeler gauge. I have one. Pretty cool to get your lash adjusted "just right".
CamBirdRacing is offline  
Old 07-20-2009, 10:20 AM
  #10  
TheRabbit
Senior Member
RACING JUNKIE
 
TheRabbit's Avatar
 
Join Date: Jan 2007
Location: Augusta, Ga.
Posts: 2,276
Default

Their will always be a debate over setting lash over hot vs cold. Hot is better, but the average racer doesn't do it fast enough to keep the temp steady. I've been through this so many times with my engine builder and this is his take on it. The lash is set and adjusted correctly during breakin once the motor is hot. Once I get it I check and see what feeler guage will fit. I don't care what size it is. Just get my feel for it. Noone can tell you .016 - .018 cold or .022 or .024 is perfect. Everybody has a different feel for .022. Some tight, some loose, some snug. .002 isn't going to make a difference, but they all need to be the same!! If you error do it on the tight side! What I'm trying to say is set them the same everytime YOURSELF. Smaller or lazy cams likes more lash, but even that isn't always 100% true. A good valve train SHOULD NOT MOVE. IF IT DOES SOMETHING IS WRONG!!! Take notes which ones you have to adjust and which way. If you have to keep getting tighter you probably have a seat problem. Bottom line is if you have to adjust the same ones next time look at everything really close!!
TheRabbit is offline  

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -