What zero lash on the lifter rod should feel like?

[Hugomartin]

Sounds like you are now trying to diagnose a no start? How's spark, is it orange or blue ? Is there fuel squirting?

yes there is fuel squirting....but i know 4,6,8 have no compression so it shouldnt run anyways even if spark is good?... If i have a weak spark how would i diagnose that other than a visual test? Thanks

 

[Hugomartin]

i had to edit post . Before i used jumper cables from a doner i measured 12.1 volts on the battery with multimeter

when jumper cables were hooked up from donor car it got to 12.7 v on the multimeter on square body

 

[DoubleDingo]

yes there is fuel squirting....but i know 4,6,8 have no compression so it shouldnt run anyways even if spark is good?... If i have a weak spark how would i diagnose that other than a visual test? Thanks

Did they have no compression before adjusting the valves? If not, you may have turned the nut too far and the valves won't close

 

[Bextreme04]

yes there is fuel squirting....but i know 4,6,8 have no compression so it shouldnt run anyways even if spark is good?... If i have a weak spark how would i diagnose that other than a visual test? Thanks

There aren't many things that will cause zero compression on three cylinders. I would start by backing the nuts on all rockers on those cylinders all the way off. Then manually turn the engine over and do the adjustments on those cylinders using the method in the video I posted. You should see the pushrods moving up and down on all cylinders while doing this. Then run your compression test again.

If it is still zeroes... you are going to have to start pulling the engine apart. It takes a lot of wrong things to get zero compression on more than one cylinder. You can have a lot wrong mechanically and just have low compression, zero requires a big issue. I had about 120psi on one cylinder(the rest were ~150-165) and when I took the engine apart the top ring was in about 300 pieces. Zero compression requires valves to be completely not seating or a hole in a part that shouldn't have a hole.

 

[ChuckN]

I've only adjusted chevy rockers while running. But reading this has been interesting, I think I'll try this method next time soon.

My dad swore that with it running was the only way. He’d cut up a piece of cardboard to catch the flying oil, man it was always some sort of mess.

Doing the zero lash and then 1/2 turn has worked great in my experience. Some guys swear by 3/4 turn, others 1/2. I’ve had good results with 1/2.

 

[Bextreme04]

My dad swore that with it running was the only way. He’d cut up a piece of cardboard to catch the flying oil, man it was always some sort of mess.

Doing the zero lash and then 1/2 turn has worked great in my experience. Some guys swear by 3/4 turn, others 1/2. I’ve had good results with 1/2.

It's definitely the fastest way... if it is already close enough to run. You can get clip on pieces that will keep it from spraying with stock rockers and I've also seen people cut the top off cheap stock valve covers and use those to keep it from making a mess. Personally I've found using the EOIC method with a starter trigger button to be just as fast and far more precise.

 

[squaredeal91]

Same here, My dad also taught me the running method and always done it like that because. Not much splatter when warm and idling low but on the last sbc adjustment I crudely cut out some cheap stamped covers and seemed to help allot. But I do see benefits in the EOIC method.

 

[Hugomartin]

There aren't many things that will cause zero compression on three cylinders. I would start by backing the nuts on all rockers on those cylinders all the way off. Then manually turn the engine over and do the adjustments on those cylinders using the method in the video I posted. You should see the pushrods moving up and down on all cylinders while doing this. Then run your compression test again.

If it is still zeroes... you are going to have to start pulling the engine apart. It takes a lot of wrong things to get zero compression on more than one cylinder. You can have a lot wrong mechanically and just have low compression, zero requires a big issue. I had about 120psi on one cylinder(the rest were ~150-165) and when I took the engine apart the top ring was in about 300 pieces. Zero compression requires valves to be completely not seating or a hole in a part that shouldn't have a hole.

Update I tried backing off on the nuts and got only 20psi compression so a slight improvement but basically like you said I now need to go deeper and remove rocker arms?

 

[Hugomartin]

When cranking the engine with valve cover off I noticed all the rocker arms did move as they should

 

[Bextreme04]

Update I tried backing off on the nuts and got only 20psi compression so a slight improvement but basically like you said I now need to go deeper and remove rocker arms?

You backed them all the way off and then checked compression? Or you backed them all the way off, then set via EOIC method, then checked?

If you had them set, and only got 20psi, then you have a few things that could be wrong. If all of the rockers look like they are moving the same amount while cranking, it rules out cam/lifter/pushrod issues. That means you will need the head off to check or fix any of the remaining issues it could be. Best case... valve issue. Worst case, multiple damaged pistons or cracked head/block. Maybe severely blown head gasket into the other cylinders... hard to say.

 

[squaredeal91]

Im guessing Collapsed valve springs?

 

[Hugomartin]

You backed them all the way off and then checked compression? Or you backed them all the way off, then set via EOIC method, then checked?

If you had them set, and only got 20psi, then you have a few things that could be wrong. If all of the rockers look like they are moving the same amount while cranking, it rules out cam/lifter/pushrod issues. That means you will need the head off to check or fix any of the remaining issues it could be. Best case... valve issue. Worst case, multiple damaged pistons or cracked head/block. Maybe severely blown head gasket into the other cylinders... hard to say.

I backed them off almost all the way then checked only 20 psi.

all the rockers were moving while cranking.

Great i can possibly rule out cam and pushrods

Ok to remove the head i need to remove adjusting nuts on pushrods first?? Thanks

 

[Hugomartin]

Im guessing Collapsed valve springs?

The rocker arms moved when i cranked the engine are valve springs the same as rocker arm springs?

 

[Hugomartin]

i am so ready to rip into this engine once i get some idea where to start once im loaded up on monster drinks first

 

[KnuckleBuster]

Hmm. Maybe I missed it but I didn't see it mentioned that the 'zero lash' must be when the lifter is on the base circle of the cam, like it would be at TDC of the compression stroke. Otherwise you'll be way off. I've always adjusted these to zero lash plus one turn, as factory specified. No real trick to obtaining zero lash. Just slowly tighten the nut while rotating the pushrod between your fingers until a slight resistance is felt. If you'd rather adjust while the engine is running, you can run all nuts down until there is about 4 threads left exposed above the nut. This will get it running. Then back off each nut until the rocker starts 'clicking'. Slowly tighten nut until it stops clicking and then one full turn. Done.

Everyone has their own way of doing things but I like to use factory specs. I'll try to look it up and get a copy posted.

By the way, these instructions are for the original FACTORY setup. You didn't mention why you are adjusting them, but different valvetrain components (like lifters, rockers, etc.) may require different procedures/specs. Good luck!

(Well, I finally got it posted and now realize that I left part of the info off. I'll fix it this weekend and get it posted next week. Still usable for adjustment info so I'll leave it until then.)