valve contacting piston - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

camaro eth eth · 06-16-2017, 08:38 PM

I have a 2010 cammed ss (btr stage 4, 7400 push rods, .660 valve springs) around 1500 miles on the setup and as of this last week it developed a ticking noise. pulled the valve cover today and pushrods are all straight, rockers are good and so are the springs. I put a camera in the front left cylinder spark plug hole to see and the valves at contacting the piston ever so slightly you can see the circles in the pics below. tuner said the cam gear could be loose or the timing chain could have jumped a tooth to throw the timing. or could the lifter be stuck open giving it that extra distance to strike? praying its not the lifter chewing my cam apart. anyone have any idea or the slightest clue?

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G701LE · 06-16-2017, 08:44 PM

That sucks! Hope you get it figured out.

Russell James · 06-18-2017, 11:33 AM

Was piston to valve clearance and PR length measured when built?

My guess is a real close PTV clearance, and a little valve float kissed the pistons.

PTV is tough to measure with hyd lifters. Need to make some mock up solids, and either use clay or checker springs and dial indicator to measure actual PTV.

Your tuner is throwing out wild guesses that make no sense. A cam gear problem is a catastrophic failure, so is a timing chain jump. A light piston kiss is a build or valve float problem.

Rebuild with adequate PTV, actually measuring PTV and PR length. Check spring seat pressure just to make sure one didn't go bad. I saw one car once that kissed a valve, everyone scratching their head... what could be possibly wrong... brand new PAC springs, plenty of PTV, PR length checked on build.... they finally checked spring pressure, found a broken inner spring. Weird stuff happens, especially with aftermarket parts.

If someone is just looking at the springs and determining they "look" fine... that's not actually how springs are checked.

Since your valves have already hit the pistons, the heads are coming off anyway. Send them for a valve job, replace those valves that hit. Have seat and open pressure checked. If the springs are fine, and it's just too close PTV, rethink cam choice.

06-16-2017, 08:38 PM	#1
camaro eth eth Drives: red Join Date: Jun 2016 Location: great falls montana Posts: 86	valve contacting piston I have a 2010 cammed ss (btr stage 4, 7400 push rods, .660 valve springs) around 1500 miles on the setup and as of this last week it developed a ticking noise. pulled the valve cover today and pushrods are all straight, rockers are good and so are the springs. I put a camera in the front left cylinder spark plug hole to see and the valves at contacting the piston ever so slightly you can see the circles in the pics below. tuner said the cam gear could be loose or the timing chain could have jumped a tooth to throw the timing. or could the lifter be stuck open giving it that extra distance to strike? praying its not the lifter chewing my cam apart. anyone have any idea or the slightest clue?

06-16-2017, 08:44 PM	#2
G701LE Drives: 2010 2SS/RS L99 IBM silver stipes Join Date: Dec 2015 Location: K.C. Kansas Posts: 1,329 View My Garage	That sucks! Hope you get it figured out. __________________ 2010 Imperial Blue w/ Silver stripes 2SS/RS L99 Mods = Not enough....

06-18-2017, 11:33 AM	#3
Russell James Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009 Location: Mich Posts: 4,482	Was piston to valve clearance and PR length measured when built? My guess is a real close PTV clearance, and a little valve float kissed the pistons. PTV is tough to measure with hyd lifters. Need to make some mock up solids, and either use clay or checker springs and dial indicator to measure actual PTV. Your tuner is throwing out wild guesses that make no sense. A cam gear problem is a catastrophic failure, so is a timing chain jump. A light piston kiss is a build or valve float problem. Rebuild with adequate PTV, actually measuring PTV and PR length. Check spring seat pressure just to make sure one didn't go bad. I saw one car once that kissed a valve, everyone scratching their head... what could be possibly wrong... brand new PAC springs, plenty of PTV, PR length checked on build.... they finally checked spring pressure, found a broken inner spring. Weird stuff happens, especially with aftermarket parts. If someone is just looking at the springs and determining they "look" fine... that's not actually how springs are checked. Since your valves have already hit the pistons, the heads are coming off anyway. Send them for a valve job, replace those valves that hit. Have seat and open pressure checked. If the springs are fine, and it's just too close PTV, rethink cam choice.