[dubs68camaro]

Valve lash adjustment question

After breaking in my cam with zero lash, when it's time to re-adjust, do we still do the old "zero lash plus 1/2 turn"?????

I think that's what Comp Cams said......but I'm not completely sure. Thanks!!

 

[DOUG G]

Re: Valve lash adjustment question

Zero lash and 1/4 to 1/2 turn. Zero lash is only till the play is out ...not tightened all the way, but I'm sure you know this and I only wanted to state it for someone who may not.

 

[DjD]

Re: Valve lash adjustment question

If you have a Comp hyd cam, they recomend zero lash and 1/2 turn preload. If you set them properly before initial fire up you don't have to re-adjust them after cam break-in... I have never heard of just setting them at zero lash for break-in

Getting to zero lash isn't hard but if you pick 10 guys out of a crowd at a car show to do it I bet you get 2 maybe 3 that actually set to zero. Too many use the spin the pushrod between your fingers method and set them beyond zero lash before making the 1/2 turn. The other problem is guys lean into the wrench and after they hit zero lash and pull the socket off the adjuster they haven't reached zero lash yet...

Bounce the pushrod between the rocker and the lifter and don't push down on the adjuster nut when you turn it. Zero lash is when the pushrod just stops bouncing.

Sorry, that may have been more than you were asking for...

 

[dubs68camaro]

Re: Valve lash adjustment question

If you have a Comp hyd cam, they recomend zero lash and 1/2 turn preload. If you set them properly before initial fire up you don't have to re-adjust them after cam break-in... I have never heard of just setting them at zero lash for break-in

Getting to zero lash isn't hard but if you pick 10 guys out of a crowd at a car show to do it I bet you get 2 maybe 3 that actually set to zero. Too many use the spin the pushrod between your fingers method and set them beyond zero lash before making the 1/2 turn. The other problem is guys lean into the wrench and after they hit zero lash and pull the socket off the adjuster they haven't reached zero lash yet...

Bounce the pushrod between the rocker and the lifter and don't push down on the adjuster nut when you turn it. Zero lash is when the pushrod just stops bouncing.

Sorry, that may have been more than you were asking for...

Acutally, I'm using poly locks for steel rockers (this motor has Comp roller tips rockers) so I'm not likely to make the mistake with the socket. I had someone on here tell me to do the zero lash only just like taking out the inner spring on a dual spring setup. I guess it's supposed to be better on the cam for that 1st half hour.

Someone else please chime in on this!!! I don't want to have to pop the covers and then do the half turn if I don't have too!!!!!!!

 

[dubs68camaro]

Everyone please verify....zero lash or plus 1/2 turn on initial startup??????

Okay....I'm getting different input on this. The question is one a BBC with single spring, do I only set the lash to zero and then do the 1/2 hour break in or can I go zero plus 1/2 turn (this is what's in Comps instructions)???? If I don't have to redo the lash in a 1/2 hour, I'd just soon not. I just want this cam to live and I know this parts is important. It just seems that if it was better to do the zero lash and then the half turn after the cam has run for a half hour, Comp would put that in their instructions.. What do the engine builders on this site think????? Thanks!

 

[DOUG G]

Re: Everyone please verify....zero lash or plus 1/2 turn on initial startup??????

Zero lash plus 1/2 turn (the half turn is preload) and should be done prior to start. Zero lash is only till the play is out ...not tightened all the way, but I'm sure you know this and I only wanted to state it for someone who may not.

 

[pdq67]

Re: Everyone please verify....zero lash or plus 1/2 turn on initial startup??????

Zero +1/2 a turn will be fine on start-up.

Just bring her up fast to like 2500 rpm and blip her to 3,000 up and down for say at least 20 minutes w/ a garden water hose handy if she starts to get hot b/c you may not be dead-nuts on w/ the timing..

I always leave the rad. cap loose too just so I can drown her if she starts to get hot...

pdq67

 

[JimM]

Re: Everyone please verify....zero lash or plus 1/2 turn on initial startup??????

I always readjust the valves after breakin.

One "pitfall" seems to be determining where "zero lash" is. How many posts have we read on engines that pop and spit and won't start? A healthy percentage turn out to have the valve adjustment so tight the valves won't close. Also, if all this stuff is new particularly, the lifters will probably compress quite a bit, then pump up once they have full oil pressure.

Set them a lil on the loose side. Soak the lifters in oil for several days first if you haven't all ready installed them. If you didn't soak them, be very careful about "where" zero lash is, you want the "first one." If they loosen up after a few minutes, ignore it.

 

[fatblock]

Re: Everyone please verify....zero lash or plus 1/2 turn on initial startup??????

All of the above..I agree.Also look for an instant start up.Drop your dist in correct the first time.Align the rotor with #1 terminal after stopping your timing marks at 12 degrees BTDC.This will give you suffficient initial timing advance.Prefill your carb float bowls.Place a shop fan in front of the rad and have a fire extinguisher within reach.If she does not fire in 3 or 4 revolutions...stop and find out why.The key to lobe life is an instant start and not allowed to idle and vary the rpm 2 to 3 k.After 20 minutes..drop the oil and filter and relash the valvetrain.:thumbsup:

 

[dubs68camaro]

Re: Everyone please verify....zero lash or plus 1/2 turn on initial startup??????

I always readjust the valves after breakin.

One "pitfall" seems to be determining where "zero lash" is. How many posts have we read on engines that pop and spit and won't start? A healthy percentage turn out to have the valve adjustment so tight the valves won't close. Also, if all this stuff is new particularly, the lifters will probably compress quite a bit, then pump up once they have full oil pressure.

Set them a lil on the loose side. Soak the lifters in oil for several days first if you haven't all ready installed them. If you didn't soak them, be very careful about "where" zero lash is, you want the "first one." If they loosen up after a few minutes, ignore it.

Is it, and if so why, to take a push rod and pump on the lifters while they are in a coffee can of oil?? Yes they have been soaking. I'm not too concerned about firing quickly. I've done this a few times even though I'm asking very basic questions. I do this so I don't miss something that has proven to be better than the old way. The only constent in America is change, and someone is always building a better mouse trap.

 

[oger]

Re: Everyone please verify....zero lash or plus 1/2 turn on initial startup??????

The best way I have found with new lifters is to set the valves with the intake off. You can look at the lifter and watch as the pushrod starts to compress it. You must reset the lifters as soon as the cam is broken in.

 

[DjD]

Re: Everyone please verify....zero lash or plus 1/2 turn on initial startup??????

ZERO + 1/2 turn! and go. If you run them loose you run more risk of the pushrod bouncing between the lifter and the rocker which also could cause the lifter to bounce on the cam... Most likely not going to be a problem because it's a hyd cam but if anything loose is more likely to cause a problem so adjust them properly and fire that mill up! Unless you have a real radical cam you don't need to remove any springs either...

I'm not a mechanic and most giving advice are not mechanics but I hang out at a machine shop a lot and have done cam installs before. I wouldn't give you advice if I thought it might be incorrect. If you read comp's instructions they tell you pre-soaking is a good thing but not a requirment... They tell you how to adjust the rockers too. Follow their instructions because they are the ones who will be backing you up if there is a problem...

http://www.compcams.com/Technical/Instructions/Files/145.pdf

Start on step 9 for lifter install and adjustment...

Side note: I merged your 2 threads, it is better to keep all the info together. Starting a new topic on the same subject is kinda like telling the orig folks who offered help where to go!

 

[travis]

Re: Everyone please verify....zero lash or plus 1/2 turn on initial startup??????

On a hydraulic cam, I always go zero lash plus 1/2 turn before initial fire up. And like Oger, I always set mine before installing the intake manifold for visual verification. I also have never soaked lifters before...I just smear moly lube on the foot of the lifter and then dunk the body in motor oil, holding it under for a few seconds for the air bubbles to come out. Break it in at 2000-2200 rpms, ocassionally revving it up to 3K. Cool the engine, change the oil, and recheck the valves. I've been doing it this way for 20 years and haven't lost a cam yet...the vast majority of which have been comp cams.

I've seen people try and run 0 lash for the intial fire up of a new engine, and have several pushrods pop completely off the rocker arm or out of the lifter. You can get some pretty interesting shaped pushrods doing it that way.