My exhaust pushrod is on its' way up so I'm setting the intake lash. The lifters have had a couple of days to "unload" (fully extend)

As soon as I place my rocker arm on the stud it rests up against the pushrod. Hence, the up & down method of finding zero lash is found before putting the rocker arm nut on.

Does it sound correct that I tighten down the nut to where I feel resistance from the rocker arm and then go my 1/2 to 3/4 turn? I remember backing off the nut for a few turns during removal of the stock rocker arms.

 

SBC STATIC VALVE LASH ADJUSTMENT - ENGINE ASSEMBLED OR INSTALLED

The most important step in proper setting of valve lash is providing reliable position markings on the crankshaft. Most engines with a stock timing tab and balancer should have a TDC groove in the outer ring of the balancer. It is important to verify that the groove is at TDC and hasn't slipped significantly. The TDC marker should be nearly in line with the crankshaft keyway (actually, about 7° retarded). Thus, one of the easiest ways to check this alignment is to remove the crankshaft balancer bolt and observe the keyway in relation to the TDC marking on the balancer outer ring. If the mark is relatively aligned, you can proceed. If not, you'll have to make a visible mark at the TDC position. Once you have the TDC mark verified, mark the balancer ring at a point 180° from the TDC marking. Make additional markings at 90° intervals, so that when finished you have divided the balancer into quadrants. You will use these marks to determine the positions of all cylinders through the firing order and to adjust the valves in that sequence. If you have removed the balancer center bolt, you should now replace it and torque it to 65 ft/lb - 10.5 Kg/M - 85 N/M.

Align the TDC marking with the timing tab. It is important that you use something OTHER than the crankshaft center bolt to turn the crankshaft. If you are building the engine in a stand, or have the balancer off for any reason, a crankshaft socket is indispensable. If the engine is fully assembled, a strap wrench can be very useful in turning the engine. You can also use a flywheel turning lever, or whatever suitable means other than the balancer center bolt.

Make any additional markings necessary around the timing tab to make the position more obvious, such as chalking a line on the timing tab. Remove the rocker covers if you haven't already done so. With the timing marks at TDC. The valves on the #1 cylinder will either both be closed, or the one or both will be slightly open. If either of the valves are slightly open, rotate the crankshaft one full revolution, so that both valves are fully closed. This will place the #1 cylinder at TDC in compression/firing stroke. At this position, you can adjust the valve lash on both valves on the #1 cylinder.

Start by backing off the adjusting nuts on both rockers until the push rods can be moved freely either up/down or by gently spinning the push rod under the rocker. If you are setting valves on a freshly built engine, one with lifters that may be leaking, or one with high-bleed lifters, spinning the push rod may not provide an accurate indication of the lash point, since only the lifter plunger spring may imparting force on the push rod. In such cases, checking for vertical movement is preferred. With new or unprimed (dry), leaking, or high-bleed (Rhodes) lifters, you must be very careful to determine the point at which the lifter plunger is fully extended.

When all pressure is removed, the push rods should spin or move very easily with two fingers. From this point, turn the adjusting nut clockwise slowly until the resistance on the push rod increases, or free vertical movement is eliminated. This is the zero lash point. From here, the lifter preload is applied. The factory setting specification for a stock engine is typically 5/8 to 1 turn of the adjusting nut, depending on the year, model, and your specification information source. For a higher RPM engine, it may be desirable to preload by only 1/4-1/2 turn to minimize the chance of a lifter pumping up at higher RPM and creating valve float. The lower preload adjustment on a new valve train may require an additional adjustment as the valve train "wears in" and surfaces are polished together. This is less likely on a roller camshaft engine, but can still occur. The amount of preload should be no more than 1 full turn, but the actual adjustment should be decided before you begin. If you are using jamb nuts or top-lock nuts, set the locks as necessary once the preload is set.

Once you are comfortable with the lifter preload adjustment of both valves on the #1 cylinder, turn the engine in a forward rotation (turn clockwise as viewed from the front end of the crankshaft) 90° to align the next chalk mark on the balancer with the timing tab marker. Some purists will prefer to turn the engine backward to eliminate any timing chain slack, but the typical valve timing of SBC camshafts doesn't require that amount of precision positioning.

Remember that the SBC firing order is 1-8-4-3-6-5-7-2, and that you will follow this order to adjust the valves at every 90° turn of the crankshaft. After having made two full revolutions of the crankshaft, the adjustment of all valves should be complete.

 

Once you follow the above procedure for what valves to adjust at what TDC points you want to spin the pushrod in your hand while turning the nut slowly. Once you feel the slightest resistance turning the pushrod you've found 0 lash. Then tighten it up the rest of the way slowly. The OEM rockers are suppoosed to be 1 full turn in the book past 0. I have my roller rockers at 1/4 turn past 0.

 

I like this tech tip method:

Tech Tip

 

Chuck, I like Scorp's method of twirling the pushrod between thumb & finger...it worked well for me too.

Sounds like you're getting close...and that light isn't a freight train.

 

I did both the up and down and the twist method as they both seemed to confirm zero lash at the same time.

I was most happy to see that my Morosso valve covers slipped right on without any interferenc with the rockers. I'll finish buttoning it up tomorrow and start a thread with my thoughts.

 

Chuck

Any chance of hitting the final ECS challenge of 2003 this weekend?

It'd be nice to sample feedback of the RR install by MPH judgement. :yesnod:

 

I don't think I came make it. Unless a family committment changes.

:eek: Look at you Mr. :steering: Finally drivin' that car like it should be driven :thumbs:

 

Chuck, which type of Moroso valve covers are you using?
Just curious as I used a chrome Moroso VC set last year and they deformed over little time and leaked on me.

Ohh nevermind, you have centerbolts. Those should be fine... Woops.

 

:yesnod:

 

[SNIP]My exhaust pushrod is on its' way up so I'm setting the intake lash. The lifters have had a couple of days to "unload" (fully extend)

As soon as I place my rocker arm on the stud it rests up against the pushrod. Hence, the up & down method of finding zero lash is found before putting the rocker arm nut on.

[/SNIP]

I don't think so.

Not only must the pushrod fit in the rocker cup but the roller tip of the rocker must be on the valve stem tip.

I'll bet that when the rocker "rests up against the pushrod", the other end of the rocker - the roller/valve end -isn't in contact with the valve stem tip.

Am I right?

Jake

 

First off, Jake I want to thank you four your Tech Tip. It was what I followed, along with the tips of countless others(the least of which is not 65Z01)

My findings where that when I placed the rocker arm on the stud it would slide down and make contact with the both the top of the valve stem as well as the pushrod, coming into contact with its' socket.

Its' probably a moot point now, as I started the car to let the springs go through a heat cycle at idle before, all seems to be running nicely

 

Hey, glad things worked out well for you.

Take care,

Jake

 

I just got back from a test drive. The longer I drive the worse it got. Sputtering, choking, hesitation ETC. Looks like I'll have to pop the valve covers and adjust them while the car is running.

Funny thing is the idle sounded and felt good when I started it up at lunch and just let it idle at about 600-800. But once I got the rpm's up a bit I started to run into the above problems.

 

Before you go through the nightmare that is the smoking header method of valve adjustment try it like the service manual says to do it. I've heard some people say you can't use this method on anything other than a stock cam, but I've done it on alot of engines and haven't ever had any problems.

First find TDC compression #1. For reference I always watch the valves on #6, if they're both moving I know #1 is on compression. Once you have #1 on TDC compression loosen all the valves so you'll know for sure what ones you've adjusted. Then adjust the following valves Intake #1,2,5,and 7 and exhaust #1,3,4, and 8. On the the style rockers that in your picture I just turn down them lightly by hand till they bottom (make sure the set screw is backed all the way out so it doesn't hit). Twist the push rod and try to move it up and down to confirm zero lash. Then go down 1/2 to a full turn- service manual says a full turn.

Once you've adjusted those eight, turn the engine one full turn to put # 6 at TDC compression then you can adjust the other eight valves-Intake #3, 4, 6, and 8, and exhaust #2, 5, 6, and 7.

I've always had good results using this method. Hope it works for you. Anything is better than the mess you make doing it with the engine running.

 

FWIW I do it the "book" way first and then with the car running. Sometimes the lifters bleed the oil out while sitting there so your adjustments while not running aren't always correct.

 

:iagree: There is no mistaking the zero lash point with the engine running. Roller rockers don't squirt in the arc that the stamped rockers do. Rags can be used to direct oil, and an otherwise useless valve cover can have the top cut for wrench access while retaining the oil. Maybe that light WAS a train, after all. Good luck, and...

RACE ON!!!

 

I just installed a new set of Comp Cam springs & Ti retainers on monday night. I did it one cylinder at a time, engine off, posi locks loose. Once 0 valve lash is established turn (tighten) wrench 45', then another 45', total of 180 degrees. This should be perfect.

 

I gotta double check this ! Where's my calculator???

RACE ON!!!