Best methods of setting valve lash?

Supe

MalibuRacing Junkie
May 21, 2003
15,116
0
36
Charlotte, NC
The following question was requested by one of our members:

What is the best way to lash valves on a solid roller BBC?


We can open this up to all engines, hot vs. cold lash settings, possible detrimental effects of getting it wrong, etc.
 

Robert1320

Pro Stocker
You have to check them hot. You need to know how much everything grow.
Once you hot lash is set at what you want.
If you let the motor get stone cold, after the hot adjust, and you can measure to have cold valve lash.
(Measure not adjust cold)
While check cold lash give the springs a quick pull with a spring tester to check to changing spring pressure and impending doom.
Warm motor, enjoy.

There is much more you can do just this mostly covers your question.
 

gearjammer

Weekend Racer
Feb 5, 2007
51
0
0
Troy, Michigan
I agree with Robert1320 but I would add the following methods for lashing valves

#1
You can adjust two valves at each 90-degree rotation point, starting at #1 TDC, turning the crank 90 degrees at a time seven times (measure and mark your balancer first at 90-degree intervals from TDC). Removing the plugs simplifies rotating the crank, but you were going to change them anyway, right? Proceed as follows:

TDC #1 - 8E, 2I
90 deg. - 4E, 1I
180 deg. - 3E, 8I
270 deg. - 6E, 4I
0 - 5E, 3I
90 deg. - 7E, 6I
180 deg. - 2E, 5I
270 deg. - 1E, 7I

Start at TDC #1, then rotate 90 degrees at a time, setting at .026" cold. If you like, you can then go back after you're done to each cylinder's TDC position and check clearance on that cylinder's two valves, and you'll find that they've closed up to .024", indicating that both valves are still on the ramps at TDC, as I pointed out in the beginning

#2 what I use
with the exhaust valve fully opened, set the lash on the intake valve. Rotate the engine so that the intake valve fully opens and then just begins to close (roughly 20 degrees rotation of the crank). Then set the exhaust lash.
 

COPO 572

Dragway Regular
Mar 23, 2004
1,325
0
0
Morrisville, NC 27560
Once you know what the cold setting is suppose to be, I would always set them cold. I know I really take my time when I do mine and there is no way the motor is the same temp when I finish as when I started. That would mean a lash variance exists between the valves I set in the beginning, vs. the valves I set at the end.

I set the intake valve when the same cylinder exhaust is opening, and the exhaust valves when the intake is closing.
 

doechsle

New Member
Mar 23, 2010
1
0
0
roller designs vary and some have some inversion at the opening and closing points to increase the area under the curve with a smaller seat timing number. what this does in layman's terms is it will put a little dip in the base circle just before the lobe leaves the base circle. flat tappets dont experience this. but due to this with rollers i developed a method that is sure fire and works every time. first be sure to know the firing order of the cam being used ( std or 4/7 swap or even the 4/7-3/2 windsor ford sequence). anyhoo it goes like this

first if the motor has a stud girdle you want to only loosen the bar enough to be able to turn the adjuster nut you are working on. Alot of times a stud girdle will pull on a rocker stud sideways when tightening. If you loosen the girdle all the way then adjust the rocker and tighten the girdle when it does this it will change the setting you just gave it.

start with either the intake or ex valve on cyl #1. im going to say in this example im looking to adjust the intakes. Bump the engine over watching the ex valve (yes ex valve) i like to get the ex valve just before max lift.( my little short cut). adjust the intake rocker to cam card spec. then here's the good part. bump the engine and recheck the lash. make sure its still there. of it pinches the feeler guage on the first bump then you were too close to the opening ramp and should rotate it back around and try again.( this is very important). if lash is still there after the first bump now you know you were not on the opening ramp. continue to bump and check until the rocker does pinch the feeler guage. if the lobe profile has the dip I was talking about you would notice the lash loosen about a .001 or .002 just before it opens the valve.I like to adjust in that dip if it has one. once the rocker pinches the feeler guage you know you are 1/4 turn of crank rotation away from the next firing cylinders lash setting. #8. GO AHEAD and set the lash without bumping the starter . then do the bump and check bump and check till it pinches the feeler guage . continue on to the next cyl that fires with this method till you get back to 1. This method is sure to work and once you have mastered it you can lash your motor in less than 10 minutes.
once all intakes are done do the ex valves the same way. but to find your starting point you want to bump the motor till the intake valve has fully opened and closed. then lash the ex valve and bump and check till it pinches the feeler guage. once again without bumping the starter go ahead and adjust the next firing cyl then bump and check till it pinches.

its dangerous to use the tdc and 90 degree do this one and that one method on rollers, you cannot find the dip in th elobe and it doesnt help when theres base circle run out also. try it next time.
 

Night Stalker

Dragway Regular
Nov 3, 2009
1,125
0
0
Genoa,Oh
I/E ,,, go or no go method.

set them cold .004 tighter alum or iron heads..doesn't need to be in any fire order or random order..
 

westexun

Frequent Racer
Dec 27, 2008
528
0
0
Since Night Stalker was kinda vague in his answer I'll explain it a little more in depth. I think what he's trying to say is he uses the E/O I/C method, which is when the exhaust valve starts to open set the intake valve and when the intake valve reaches max. lift and starts to close set the exhaust valve. This is the only way I've ever done it and it will work for any four cycle engine. It always amazes me that guys that drag race or build their own engines have trouble running valve. I was a t the track one night and a guy split the jamb nut on one of his polylocks and the valve backed off and he had fire belching back up thru the carb. I tryed to tell him he had a serious rocker geometry problem because of a wrong pushrod length and he just looked at me funny. When he set the valve he said he just eyeballed it to make sure it was on the base circle of the lobe. I showed him the right way to run them so he did the half of the motor that had broken jamb nut. The car picked up about a tenth right off. Like a guy said "some peoples kids".
 

78purplebu

Amateur Racer
Nov 22, 2010
101
0
16
lewes, delaware
i set roller and flat tappets the same as westexun never had a problem. set hydraulic the same to zero lash plus half turn. e/o i/c
 

racecar77

Pro Stocker
Aug 11, 2007
2,438
0
0
Crete,IL
It's for sure not rocket science. On my solid roller I've honestly never found one out of adjustment. I check them a couple of times a season. I also set them cold. I allow .005" tighter, for example .023" cold=.028" hot. Usually, at some point, or for some reason, I will have the intake manifold off once during the season. That's the easiest time to set the valves, when you can actually see the cam lobes. That's kind of cheating though. Lee
 

COPO 572

Dragway Regular
Mar 23, 2004
1,325
0
0
Morrisville, NC 27560
Oh, and take it from someone with personal (and catastrophic) experience. If you check your lash and find it needs adjustment by more than a normal variance, DO NOT ASSUME YOU MADE A MISTAKE THE LAST TIME YOU SET YOUR VALVES. Remove the intake and inspect the lifter. Wish I had.
 

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