Ok, here's the situation..

Unknown non behive style springs (long story) with patriot .585 lift camshaft. Stock lifters, straight pushrods.

At around 6400rpm the car breaks up and won't accelerate anymore, and after this pull is made, there's is a very evident "tick" coming from the engine and it slowly goes away.

Car has been data logged while this symptom occurs and everything is running fine..

Whatcha tink?

 

lifters do tick bad, when broken or bad. u got any excessive lash/looseness on any rockers?

 

what's the story on the springs?

 

None that I had noticed, just checked the pushrods today. Also, there is a very very faint tick coming from the engine at all other times, but I wrote that off to an exhaust leak on my drivers side collector. Only time I hear a loud tick is after this "valve float" occurs.

Bought them from a reputable guy in my area and they were sold to me as 918s, and I didn't know any better, put them on, and now realize they are not behive style and have a green stripe on them, so they're not 918s.

 

could be springs then.

 

I know what it could be, but I'd like to diagnose exactly what it is before I need to pull my heads if it could possibly be the lifters.

I'm sure someone out there has expierienced the same issues as I'm having.

 

what's the cam profile spec, and who's valve springs?

 

All i know is what patriot tells you, 226/226 @ .050 .585/.585 112lsa. No idea on what the valve springs are anymore.

 

no idea on springs, makes me wonder? 2 things. First, roll the motor so were you get max lift on your cam,(were the valve spring is full compressed) see if you can get a .050 feeler guage between the coils of the valve spring. If not, i would say your in a coil bind/harmonic valve spring issue. Second, if that's not your problem, pop off one intake and exhaust valve spring and have there open/closed seat pressures tested. places to start.

 

Well the reason I'm sure it's not a coil bind issue is the tick after the pull is made, and it actually did this same "valve float" at 66-6700 rpms before, until I had it tuned to shift at 6450, and it has slowly became more and more of an issue.

 

Anyone else?

 

i say lifter. why would a spring be variable like that? if the lifter isnt working properly being hydraulic and all, couldnt it allow the pushrod to do its own thing, causing the valve to not work in conjunction with the others? then, once returning to idle, the "tick" mysteriously goes away?

my vote is lifter spring or cup failure.

 

How I made sense of it in my head so far is under the extreme load and rpm it just eventually squashes the lifter, then the valve timing is way off causing this "valve float" type issue, once I'm done with the pull it makes a tick, either pushrods smacking the rockers or the lifter smacking the camshaft until it pumps back up again.. I however am only using logic as I've never researched anything like this or expierienced it and not really sure how the lifters themselves work or how they go bad.

Welp, live and learn, if you have the easy access to change your lifters while the heads are off, do it.. or you'd be me!

 

exactly my theory.


wish there was an easier way to tell without pulling the heads

 

I'd still test the springs like JPH recommended. Cheap insurance. I had a spring break way back when I was still under warranty. Lucky me.

 

I'm just going to yank the heads, change the springs, and the lifters... be done with it.

Thanks for everyone's help.