Valve Lash and Cam Timing
 

How does the valve lash effect the cam's valve timing? For example, i bought a engine with a Lunati solid lifter cam. The valve lash for both intake and exhause is.030. What does this do for the engine?

looser valve lash will give u more top end, tighter will give u more torque of the bottom

valve timing
 

Are you sure about that? Loosening the valve lash makes the cam seem smaller, which helps bottom end performance. Tightening makes rthe cam seem larger, which helps the top end. That has been my experience.

If you play with lash up to .004 looser and tighter, you may find minor improvement. It will also tell you if cam you have is too large or small if it wants lash set different than factory setting. I set lash .006" tighter cold than hot specs for BBC with aluminum heads and iron block.

Wrong
 

This advice given above is exactly wrong. More lash gives less duration and tighter gives more duration. More duration will enhance the top end and likely remove some from the bottom end. You must respect the manufactures intended valve lash and not deviate more than .010" either way, too louse a setting will hammer the lifter off the lobe causing damage.
Bruce

Re: Wrong
 

X2....I know first hand about the roller damage. I used to think they would tighten up when HOT...of course this is 100% wrong but back then I didn't know...I set them cold just a little loose thinking they would be just right when hot....it's the opposite.I busted a roller lifter(and a block) after 20 something passes. live and learn.

Would anyone care to elaborate, on the "correct" way to adjust valve lash? :twisted:

I'll get the popcorn, and drinks. :)

:lol: I remember that...

This is how I adjust valves. The website has excellent info on valve adjustments but there is too much info to list here.

http://www.centuryperformance.com/ad...h-spg-149.html



Valve Adjustment Procedure - The Quick and Accurate Way:
First, view this little chart below for Small and Big Block Chevy Engines that I made and see if you can understand it. There is more of an explanation below the chart. For other engines you will use the firing order that matches your engine to create a similar chart. This chart is based upon "opposite" cylinders of your firing order. (see below)
Intake Valve Adjustment: ENGINE OFF!
■with #1 cylinder Intake Valve at full valve lift .... Adjust #6 Intake Valve
■with #8 cylinder Intake Valve at full valve lift .... Adjust #5 Intake Valve
■with #4 cylinder Intake Valve at full valve lift .... Adjust #7 Intake Valve
■with #3 cylinder Intake Valve at full valve lift .... Adjust #2 Intake Valve
■with #6 cylinder Intake Valve at full valve lift .... Adjust #1 Intake Valve
■with #5 cylinder Intake Valve at full valve lift .... Adjust #8 Intake Valve
■with #7 cylinder Intake Valve at full valve lift .... Adjust #4 Intake Valve
■with #2 cylinder Intake Valve at full valve lift .... Adjust #3 Intake Valve
Exhaust Valve Adjustment: ENGINE OFF!
You will notice that this is the same procedure and sequence as the intake valves listed above. Only now you are adjusting ONLY the exhaust valves the same way.
■with #1 cylinder Exhaust Valve at full valve lift .... Adjust #6 Exhaust Valve
■with #8 cylinder Exhaust Valve at full valve lift .... Adjust #5 Exhaust Valve
■with #4 cylinder Exhaust Valve at full valve lift .... Adjust #7 Exhaust Valve
■with #3 cylinder Exhaust Valve at full valve lift .... Adjust #2 Exhaust Valve
■with #6 cylinder Exhaust Valve at full valve lift .... Adjust #1 Exhaust Valve
■with #5 cylinder Exhaust Valve at full valve lift .... Adjust #8 Exhaust Valve
■with #7 cylinder Exhaust Valve at full valve lift .... Adjust #4 Exhaust Valve
■with #2 cylinder Exhaust Valve at full valve lift .... Adjust #3 Exhaust Valve

Yes but this info needs to be adjusted for altered cams, 4-7 swap cams or 4-7-,2-3 swap cams.

The easiest way I have been taught to adjust valves is from reher morrison. If you take one cylinder at a time, when the exhaust valve begins to open you adjust the intake valve, Rotate the motor and when the intake valve begins to close adjust the exhaust valve.
I also found that when I set the lash cold i need to go back around once the motor warms up and adjust them again because it changes significantly. I always check them now when the motor is hot.

when the intake valve begins to close



Its when the intake is ALMOST closed adjust the exhaust valve on that particular cylinder.

I've always adjusted them this way.Hot.
pop the distrib cap rotate(bump) motor to no. 1 on cap.Set balancer to TDC 0....Adjust both intake and exhaust for no.1 cylinder

Rotate counter clockwise 90 degrees or 270 on balancer and set both for no. 8

Rotate counter clockwise 90 degrees or 180 on balancer and set both for no.4

Rotate counter clockwise 90 degrees or 90 on balancer and set both for no. 3

Rotate counter clockwise 90 degrees or 0 on balancer and set both for no. 6

Rotate counter clockwise 90 degrees or 270 on balancer and set both for no.5

Rotate counter clockwise 90 degrees or 180 on balancer and set both for no. 7

Rotate counter clockwise 90 degrees or 90 on balancer and set both for no. 2

Rotate counter clockwise 90 degrees or 0 on the balancer and your back to no.1 again... :wink:

Button on firewall. and maybe 10 minutes.

I use the EOIC method and set them cold. Trying to do it hot sucks plus by the time you get them all done the temp has changed so how can you be consistant? I set mine .006 tight cold.

HMMM, not one mention, of the "white rabbit, and the bird with a flexible bill," method. :o

I didn't know you were looking for the high performance "white rabbit, and the bird with a flexible bill," method. I didn't know you had a vette engine. :lol:

X2> This is my method too.

Lash
 

Tod,
In My Few Years,I ALWAYS go .004,Tight Cold IRON Block,Alu.Head.
Now with a ALL ALUMINUM Motor,that is a Shot in the..............Well lets just Say TRIAL and ERROR!?
But,if .006 works for you,than Use it!!!
Even when You set the Lash @ X,it may be DIFFERENT that the Way I FEEL X?
But a Constant Proceedure is a GOOD Rule of Thumb!
Later
G 8)

Re: Lash
 

\


Ok, so as a beginner I have to say I feel like Tod said... by the time i get to the other bank, I am loosing temp & I must work fast. Again, from a beginner standpoint, I hate to rush. So- (correct me if I am wrong) there is about a .02 variance from hot/cold right? So if my lash is .26/.26 @ temp, I can safely go .24/.24 cold right??

wow i feel kinda retarded now, lol i guess i just wrote it backards

I adjust mine like Demented explained. Exhaust starts to open, adjust the intake. When the intake starts to close adjust the exhaust. I also adjust them like Tod said, .006 tighter when cold. Works out great for me.

TS1955

What ever
 

Don't have to feel like that. Be happy you got the correct answer by answering the question incorrectly.
Get it?
Bruce

Not sure I would do this on today's cam profiles. You are not necessarily on the lobe base circle when the piston is at TDC. Bet if you went back and checked using the EOIC method the lash would be different. On my 4-7 swap BBC the intake will not be fully on the base circle until the exh. is nearly fully open. 8) JB

If your in doubt go back to a hydrualic and leave it alone

adjusting valves
 

SC4405 is 100% right, if traysvega was talking about adjusting a roller cam. only way trays way works if for flat tappet solid cams and hydraulic rollers. solid rollers must be done EO_IC or by other ways if you have them chevy art

I got the number .006 tight by setting them hot and then coming back the next day and checking them cold. Also I use the go/no go method so mine is the same every time...no variation for feel...or at least not much.

lol.... :lol:

Valve lash threads, never fail to bring a few grins........It's almost a tradition.

Would anyone like some popcorn? BWAHAHAHAHA

All of the treads I got on my question are really informative. The CAM card for the Lunati cam in my engine says to set the lash at 30 - 30. Surprised me. I didn't think what I measured was correct. Guess I'm wrong. Thanks everybody.............

Can you give us exact,step by step instructions as to how to make that popcorn?

http://forums.racingjunk.com/viewtop...er=asc&start=0

setting valve lash
 

you guys always get right back with answers and i always listen. i have sbc with steel block and steel chevy heads. i adjust my valves sort of opposite of the aluminum head way. i set mine cold and set them aboune .004 LOOSE as i think the steel does just opposite movement than metal ive done it this way for15 years and it seems to work, but i could be wrong. think my engine builder told me to do it this way cold, and i always do them cold. i am open to your good advice thanks art PS i also use the EO_IC method, but i do it in a little more exact fashion. i adjust the intake when the exhaust is down 1/3 of the way(not all the way down or just starting down) and i adjust the exhaust when the intake is all the way open and 1/2 the way back up to closed. a few top tuners and cam manufacturers have said this is the best way to get the valves adjusted right using this eo-ic method art

Valve adj. The never ending and always debatable topic.

Just out of curosity I checked out Crane's web site.
"With iron block and iron heads, add .002"
With iron block and aluminum heads, subtract .006".
With both aluminum block and heads, subtract .012".
Remember this correction adjustment is approximate and is only meant to get you close for the initial start up of the engine. After the engine is warmed up to its proper operating temperature range, you must go back and reset all the valves to the proper "hot" valve lash settings"


I use to adjust, adjust, and adjust my valves. I finally bought some good rocker arms and (also sold my ford lol) now harldy ever even check 'em.
If nothing is wrong they SHOULD NOT CHANGE between inspections.
If they keep changing, either your "feel" is not precise or something is wrong. Always note which valve is off, how much it was off. If it's the same valve(s) each time look for something going wrong.

BTW I think you should adjust 1 valve, make a pass down the strip and adjust another. Do this until you have them all adjusted! :lol:

I get the motor hot, check one side, then heat it up a little and check the other side. It doesn't take long to check one side, but long enough for it to cool down a good bit by the time you get ready to check the other side.
One good tip. If it's a high compression motor pull the plugs out. It's a lot easier on the starter if you do and really a lot easier if you turn the motor by hand.

1 Disconnect the battery.
2 Place in microwave and heat for 3 min. ( DO NOT BY ACCIDENT HIT 3000. AND LEAVE THE KITCHEN) I did this one time. I actually went to take a dump and hit 3000 on the micro wave. When I smelled the popcorn burning I hauled ass to the kitchen to find one hell of a fire in the microwave. The smell of burnt popcorn was so bad I almost had to leave the house and stay at a motel. I had to throw the microwave away and it was a christmas present I got the day before. (Stupid is all I can say):oops: It took weeks to get that nasty smell out of my house.

3rd. Open bag away from body. Contents may be hot. (No schitte)

Nope, I do it the wrong way. :)

valve adjust
 

thanks rabbit. maybe i was only going .002 loose now that i think about it. in any event i will adjust just as you say with the .002 number(looser) this sound just right and i am sure others will agree with this. its amazing how different metals respond to hot and cold art

I actually this weekend before the going to the track tried this...first my way HOT....Had 2 valves only a very very small amount loose..adjusted...Then second ran it again HOT and did the EOIC method....not one valve was different from my first adjustment.Not sure but my way works.I've done this long ago with the same results on a older cam profile roller with no difference so I continued on this fairly new profile (Crower Ultra action Roller).Not sure but think I'll continue with my FAST and efficient adjustment..Also if cold lash setting was the best way to do it,wouldn't you think ALL the cam Manufactures Cards would read "COLD LASH SETTING"....Instead of HOT ... :roll: make yeah go hmmmmm...

I think 6 people could check 'em right now and still adjust 'em a little. In other words, I like it now go racing and have fun. :D

Re: valve adjust
 

AMEN. Hot metal expands... so you would think tighter lash/less forgiving.... Cold metal... NEVERMIND. I hate this crap.... I will just follow it & not try to understand at this point.

After you have adjusted the valves hot you should be able to check them cold and use the setting as a reference point. It should be tighter due to the different expansion coefficients in the engine (Heads, block, rockers. valves, lifters, cam, pushrods etc,). Once you have the cold setting you can set them hot or cold. Just annotate the value on your cam card.

They can't give you a cold lash setting because they do not know every componant of your engine...aluminum heads/iron block, or iron heads iron block etc..The reason the EOIC method works no matter what the cam profile is is because the way an internal combustion 4 stroke engine runs never changes. intake compression power exhaust. If the exhaust valve is opening there is no way the intake valve can not be closed because it just finished the power stroke and is starting the exhaust stroke...intake valve will always be closed...when the intake is on it's way closed then the engine is obviously about to start it's compression stroke. The exhaust valve will always be closed on the compression stroke,obviously.

Some people like to get their fingers burnt and be in a rush, some dont.

I've personally done it both ways.

BUT, I never will adjust them HOT again sense I figured out I can do it just as accurately using the cold method.
Go ahead burn your fingers, do a rush job, make a mistake, see if I care :wink:

[quote="cepx111"][quote="traysvega"][quote="sc4405"] Chuck Norris uses the EOIC method with the engine running.