1989 vette coup auto 104k miles with brand new ZZ4 short block (stock cam and roller lifters)

Got the ZZ4 short block in and bolted in the old intake and serviced heads. I have all smog stuff in to be cal smog compatible - along with A/C.I primed the oil pump yesterday and attempted to start (after a couple days rechecking everything) - and the engine had absolutely no

compression. It just whizzed around with the starter engaged.

After a nightmare night of double checking timing and stuff, all looked good there. I hooked up a tube to the no.1 spark plug hole and could blow easily (at TDC compression stroke) - no compression whatsoever.

I thought the ZZ4 shortblock had no rings, or that the heads weren't seated properly. Both nightmare scenarios - but when I loosened the rocker nut for no.1 cylinder intake and exhaust, I got full compression (by not being able to blow into spark plug hole). That was quite a relief for me just a couple hours ago.

I apparently over tightened all the valves - but I did it by my service manual. I went to zero lash where I couldn't rotate the push rod, and then went full (360) turn.

When I just redid no. 1, after I had zero lash, I was only able to tighten slightly less than 1/4 turn before I lost compression (checking by blowing into plug hole). That really surprised me. I did this on my stock engine last year with 1 full turn and that worked fine. Maybe the difference is due to the difference in head gaskets - not sure, but I'll go with almost 1/4 turn for the rest of the valves. Any problems with this?

I'd like to run the engine (for the first time) to check the valves chatter, but there's so much stuff to hook up (A/C compressor, EGR crossover, and electrical connectors) - would it make sense to bolt it all back together and hope for the best, or would you recommend leaving the valve covers accessible first, leaving the A/C hanging on the side, and taking off the serpentine belt and then running like that for checkout?

 

You might be pushing the plunger down on the lifter w/o knowing. When there is no up/down movement on the pushrod give it your preload.
The rod can still spin if the lifter isnt pumped up giving you a false sense of where 0 preload is at.
Some will tighten down the rocker til it stops with a .015 feeler gauge then go 1/2-3/4 turn
Is your lifter on the heel of the cam when you do this? What method?

 

Try spinning the pushrod until you feel a slight resistance while tightening. Then go 1/2 a turn. Check compression again. Do it on 1 cylinder first to see how it plays out.

 

I have to ask by now I am sure that your lifters are all pumped up. but before installing them did you submerge them in oil and work the air out. if you didn't odds are Cruisinartvette is rite. an un pumped lifter has little resistance and is easily over tightened. I would say back them off a bit spin the motor until it has oil threw out, and follow the procedure again. or you can live with the mess a bit and adjust the rockers on a running engine

 

I'm using the intake/exhaust method (8 on TDC compression no. 1, rotate crank 360 and do the other 8 intake/exhaust).

My original method was to ensure I was on the base of the cam lobe by sequencing each reaching max intake/exhaust lift, and do the opposing intake/exhaust (while on the base of the cam).

I was just on the passenger side and checked compression on no. 6 with zero plus 1/4 and it holds compression, going a little more and no compression.

I'm figuring out that my best method is to get zero lash checking no up/down on rods and slight resistance when turning, then going 1/4 turn. At the final setting, I can rotate the rod around but with a lot of resistance. If I tighten it so that I can not rotate the rod, there is then no compression.

I am really surprised how sensitive this is. Heads and valves were serviced recently. Nice to know that its symmetric on both valve sides. Plan to button it all back in the morning and fire it up (unless I get further advice). Everyone that talks about doing it with the engine running probably doesn't have all the smog stuff and A/C on top.

 

No, I did not submerge the roller lifters in oil - I did see somewhere to do this but I didn't understand why. I cleaned them and they were dry for about a month. I did prime the engine's oil pump for at least 2 or three minutes the other day with the lifters in there of course.

I guess I didn't understand why the roller lifters needed to be placed in oil. I thought they were just solid metal with bearings.

 

Sounds like either you lifters are not full of oil or the valves are not fully closed at adjustment time.

When adjusting valves on my '88 I used a Comp Cams method:
- rotate the crank till the Exh is just opening and set the Int
- rotate the crank till the Int is just closing and set the Exh.
To set a gap I tighten 1/2 turn + 1/8 to set the plunger very near mid travel within the lifter.

 

One funny note is that I remember when I adjusted the valves a few days ago, the engine got easier to turn as I adjusted them. I clearly lost compression then and not experienced enough to recognize that!

Funnier yet is thinking I got a new ZZ4 short block and they forgot to put piston rings on.

 

Dont spin the pushrods. Wiggle them up and down. No wiggle = zero lash. Then go 3/4 turn.

 

I have found that if you have the stock rocker studs, stock rockers and stock lock nuts that the distance from the end of the stud to the top of the nut will be very close to 0.200". Use that as a preliminary setup and then adjust them hot and running.

 

They are hydraulic roller lifters, NOT solid.

 

Yes, I used this method on my first attempt. Again note that by blowing into the spark plug hole with a hose attached (for cylinder 1 and 6 at least), anything more than 1/4 turn has no compression.

I admit that when I first set zero lash, I originally made sure I had very much resistance, now I have very little resistance to turn at zero lash and some resistance after a quarter turn.

Last year when I did this, it worked fine with a full turn - but the roller lifters were wet back then since I only did a head gasket swap. Maybe this is the key.

 

If the valve is opening when you tighten the nut and you loose compression you have the valves too tight. BACK OFF on all the nuts so they are loose and start again.

Adjusting valves on the Corvette standard GM method:

1) Remove the spark plugs. This makes it much easier to turn the engine by hand.

2) I believe that the nut in the center of the bottom pulley on the balancer is 5/8”. Use a six point 5/8” socket to turn the engine over by hand to line up the timing marks. Place a finger in the spark plug hole for plug #1 as you turn the engine over. You are trying to determine if the engine is on compression as you line up the marks. If you feel the air pushing against your finger as you line up the marks, you have compression in cylinder #1. Align the timing marks.

3) Now adjust the valves as follows:
Intake #1, 2, 5 and 7 then adjust Exhaust 1, 3, 4 and 8.
Note: If you are not sure which valve is the intake and which is the exhaust, look down at the exhaust manifold. The exhaust valve will be right above the exhaust pipe for the cylinder you are looking at.

4) Turn the engine 360 degrees and line up the timing marks again. Now adjust the following:
Intake 3, 4, 6 and 8 then adjust Exhaust 2, 5, 6 and 7.

You are now finished with your adjustment. I usually tighten the lock nut 3/4 turn after adjusting to zero lash.


The above directions is using the standard twist the rod until you feel resistance. Years of doing this always left me uneasy not knowing if the rod was solid and by finger and thumb were slipping because of the oil.

Forum member JoeC came up with the following, this works very well and I now use it 100% of the time. Follow the sequence above, but use the feeler gauge.

BTW, I tried something a little unconventional on adjusting hydraulic lifters. One thing that always bothered me is the statement "spin the pushrod until resistance is felt" that seems a little too subjective to me. So I tried this: I set "zero" lash with a .0015" feeler gauge while slowly turning the adjusting nut. {place the feeler gauge between the top of the valve stem and the rocker arm.} When I felt the feeler gauge grab, I was fairly confident I was about .001 from zero lash. At that point, I turned the adjusting nut 3/4 turn. I recently read that one turn is equivalent to .040" because of the thread pitch on the threaded rocker arm stud, so 3/4 turn should give you about .030" adjustment. I also read that within a hydraulic lifter there is .060 total plunger movement, and ideally you want to be just about in the middle of that range, or .030 inch. I don't know if I’m out in left field on what I did, but I feel I got a really consistent valve adjustment across the board. If you think you might have a tight cylinder, maybe give this a try - it seemed to work for me...

again, thanks for all your help - take care -

JoeC

 

You need to start over you only tighten the rocker until all of the free play is eliminated from the pushrod and then go an extra 1/2 turn. With new lifters the rocker will easily spin even with the free play eliminated, you will feel a slight increase in resistance when the free play is eliminated, that is when you add the 1/2 turn. Your current method of going until it stops spinning is too far.

 

THIS ↑↑↑

Sounds like you have to much preload on collapsed lifters and the valves are staying open.

Back the rockers off until 2 or 3 threads are showing on the stud above the stock rocker arm nut.{Loose} Pull the fuel pump fuse so the engine doesn't flood and crank the engine over until you are getting oil to all the rocker arms. Don't overheat the starter, or use a distributor primer with a drill.
If the rocker arms are getting oil, the lifters are pumped up. Set zero lash and add 1/2 to 3/4 turn on the rocker nuts.

 

That is way PAST zero lash; zero lash is where spinning the push rod GENTLY between two finger tips, the first bit of resistance (drag) is felt.

If you CAN'T rotate the push rod....well, that's way too far

 

 

Indeed, you should "just" feel a very slight increase in resistance as you "slowly" tighten the nut.

At this point I might pour some motor oil down the pushrod holes and let it stand overnight before trying the adjustment again. Or pull the dist. and spin up the cam shaft.

 

I've had trouble with the "spinning the pushrod" method as well. What I wound up doing was putting a .0015 feeler gauge between the rocker arm and the valve. I then tightened the polylock until I felt pressure on the feeler gauge while moving it back and forth. I realize that's going to be .0015" difference but it doesn't seem to matter.

 

Exactly the method I used on my last round. And as everyone is saying, zero lash is subjective (especially with oily fingers) when based on rod spinning - so I am now basing it on no up/down movement and very very slight resistance on turning.

My method now also involves taking out spark plus one and six and insert a tube to ensure I don't loose compression when I do the final turn after my determination of zero lash. Note that this is only 1/4 turn for me before I loose compression.

When I primed the oil pump with the drill, it really took a lot of power. I think I burnt out my drill doing it - for a total of about 3 minutes for 15 second stints - letting the drill cool down in-between.

What an interesting noise to have zero compression on all cylinders, sounded like an electric car almost. I only cranked a couple times before I went to diagnostic mode.

No car for almost 2 months, what a project to install a ZZ4 short block. I'll post results if I get it running shortly.