Got a weird one. The pushrod on number eight intake fell out of the rocker arm today. Noticed it immediately when the motor fired up. Slight miss and mechanical ticking sound - hard to distinguish from the normal racket the roller lifters make.

Motor is a 400 based 512 with Comp Cams retrofit roller lifters and adjustable rockers.

This is the second time it has done it. Same hole as last time. Some of the photos show damage to the rocker, adjuster and scuffing on the pushrod end. Lash is set the same as the others. Inner and outer springs seem to be ok. Motor is three years old now with a few thousand street miles. Any ideas? I'm just fishing for advice before I pop the intake to inspect the lifters.

Thanks...

Hyd roller lifter collapsed?

This is only if it’s a hyd roller.......

Too much to type for the long version.........
Always happens right at start up?

I’ve had it happen here, and have talked to several others that have had the same thing happen.

The short answer is........try running more lifter preload.

From the point of where the plunger is preloaded to, to the plunger being bottomed out in the lifter...... has to be less distance than the depth of the adjuster screw cup in the rocker arm.

The adjuster cup is .120” deep.
Set the lifter preload so it’s .090”-.100” from being bottomed out.

Sorry, should have lead with this information. Yes, it is a hydraulic roller and the couple times this has happened was at startup. Motor always ran fine until parked and this only happened after it was allowed to sit overnight.

I'll give it a go with more preload then, .095" from the bottom.

I'm still going to pop the intake and inspect the lifter. While I'm in it I can use the opportunity to rephase the distributor gear and install the Holley distributor to allow for computer controlled timing.

Do you think the damage the underside of the rocker warrants replacement? I'm going to get a new adjuster screw anyways seeing as how it's beat up.

Thanks guys.

I wouldn’t worry about the rocker, but would replace the adjuster.

i would polish out the rocker damage to prevent any stress cracks from forming.

Been there done that, had to do it more than once
Buy the good adjusters, not the cheapest ones you can find

I would add... Do a leakdown or at least a compression test. Looks like it ran with the pushrod real close to the fulcrum. That is a huge rocker ratio jump. Possible to bend a valve or squash a valve seal, etc..
Just as precaution, no likely damage. Best to be sure though.

Good time to look at the rest of the valvetrain.
I'd be wondering "why just one?" and "why that one?"

How much preload are you currently running? And, how did you arrive at that?

Good thinking, I thought the same, but also thought it lost a bunch of preload with no adjuster. Maybe the two to one ratio was made up for by a loss of .100+ length

You have a naughty lifter due to dirt or other issues. It collapses when shutdown depending on lobe position. Pops the push rod on startup. Pull the intake and replace or rebuild lifter. I don't recommend adding adding preload unless it was a temporary repair as it messes up geometry. Better replace the push rod and rocker arm too.

Agreed that hyd lifter gets it's oil pushed out when parked at an open position but the pushrod could come out if running very little preload. Some run 1/2 turn preload on an adjuster directly on the pushrod which is only .020 preload.

Could run 2 full turns for .083 with less chance of this happening.

More preload could also help, just starts getting risky if your valve/piston is close and the system loses control at high rpm. (though that's obviously a problem either way, could crash valves if it lofts and there's a ton of preload).

Doesn't change much geometry on a shaft system, well at least rocker to valve. I suppose too many threads below the rocker on the adjuster isn't the best thing but from the photos it seems like it would be ok.

I have done several hyd roller cams. The first few I had comp lifters and had the exact problem. I tried with putting more pre load in it and that worked but didn't feel comfortable with that so after that only used morels and never had a problem again.

I would agree it is most likely lifter pump down. It might be a tight valve guide, but with the time on the engine not likely. I think I would rather go with a better rocker set up, and the traditional ball and cup type push rod. Paying attention to pushrod length. The further the adjuster extends past the rocker arm, the arc of movement, will have a greater tendency to kick out the push rod. The fit of the pushrod in the rocker is critical as well, no mater which type of push rod you use. I never use the type of rocker arm you show because of the issues I mentioned. Just me never liked the look of them.

This a very common problem. It used to be believed ALL these types of failures was do to dirt and debris etc, but I am here to tell you, not always the case. Sometimes a little more pre load helps, but more so, the industry is having issues with hydraulic roller lifters from several manufactures. Especially Comp and Morel. ( yes, Morel also) .I am in a group of engine builders on a private forum from across the country, and almost everyday, a hydraulic lifter issue pops up. I could write for hours about this. But here is my best condensed version. Buy Gatorman, GS Products,Crane or Johnson ( NOT Hylift Johnson).

In every case where I’ve had a conversation with someone about the pushrods falling out........ it’s always been at start up(and was running fine when the engine was shut off)........ and was involving a hyd lifter(the motor we had here with this problem had a very mild HFT cam).

I have not heard of a single incident where the pushrod fell out during start up when a solid lifter was being used.

Some of the people I spoke to that had it happen multiple times(on random cylinders) solved it by swapping to solid roller lifters being run with very tight lash settings.

The deeper the “cup” is(whether in the rocker or the pushrod), and the more preload you run......the less likely it is you’ll encounter this issue.

Also, hyd lifters with less plunger travel will be less prone to have this issue.

I've never heard of this issue with an OEM engine so I'm wondering if the problem has something to do with aftermarket parts and/or assembly error and/or high lift lobes?

There was a post on here not long ago. It was asking about big cam/ spring/ hydr roller lifter. I’ve never known anyone personally to make it work, I read about others that have no problem. The cure for bleed down in my shop is to put a solid lifter in the car. 100% success rate.
I wish I knew more about making a hydr roller work well.

The pushrod socket on an OE stamped rocker is .180” deep, and the lifters are preloaded to about 1/2 their travel.
Aside from a valve getting stuck open, there isn’t any way the pushrod could come out........ even if the lifter plunger were stuck bottomed out.