# Valves hitting the top of pistons



## amdoverclocker (Dec 21, 2010)

I am replacing all gaskets on the top half of my motor (LS1). I have the heads being cleaned today. When I was cleaning off the top of my block and heads, I noticed some of the pistons have valve marks on them (see below). Anything to worry about? None of them look too bad. This is my DD that has 105K hard miles on it. Motor is all stock. Thoughts? Thanks!


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## svede1212 (Nov 1, 2005)

If you're all stock the only way to have the valves kiss the pistons is to have valve float. Check your pushrods by rolling them on a totally flat surface. You could have bent one.

BTW I sure wouldn't have had the heads off just to replace gaskets without being in there for something else like lifters or getting head work. At 105,000 and hard driving your lifters may be near the end of their days


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## amdoverclocker (Dec 21, 2010)

I didn't intend on doing more then the head gasket but you have convinced me. :cheers I rolled the push rods and they all appear to have the same wobble so I don't know if that's how they should be or not. Care. I ordered some Comp Cam push rods and LS7 lifters from Texas Speed and Performance. I'm hoping they get here by this weekend but I'm not holding my breath. I thought about doing my cam as well but that's more money then I can spend now. I still need to rebuild my transmission and get a new clutch. Thanks for making me poorer! :seeya


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## svede1212 (Nov 1, 2005)

If they wobble at all replace them. They should roll smooth. With the LS7 lifters you should also replace the plastic lifter trays as they are worn out (cheap). I'd check on the push rod length. I believe the LS7 lifters are a touch taller requiring a shorter push rod. There's some threads on LS1gto. I'm going from feeble memory but I know my Lunatis were .050 taller and with my milled 243s I needed a 7.3-7.325. With my link bar lifters you don't use the trays.


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## svede1212 (Nov 1, 2005)

I checked on LS1gto and that's what they said that the lifters were .050 higher needing a shorter PR. In case you didn't know the lifter trays are plastic trays with 4 holes in them (2 trays per side). One side of the hole has a flat spot and the lifter is round with a corresponding flat spot. The purpose of the tray is to keep the lifter roller aligned in the right direction to roll on the cam lobes. When the plastic tray wears out from a bizzilion strokes the lifter can turn. When that happens the cam is gone and the lifter too plus maybe other stuff. It's happened more than once and from the piston contact I'd say that car has seen some spirited driving.


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## amdoverclocker (Dec 21, 2010)

Thanks for the advice. I sent them a message to change my order to a 7.350 PR and added the plastic things. I thought about replacing those earlier but I decided against it since I couldn't find a reason to replace them. But it makes sense now. I'll update as I go. Thanks again!


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## amdoverclocker (Dec 21, 2010)

GOD DAMNIT! Now you have me wanting to swap cams now. Uhgg! :willy::willy::willy::willy::willy::willy::willy:

:lol:


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## GTPpower (Aug 1, 2012)

Might as well since you're in there.


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## svede1212 (Nov 1, 2005)

"while I'm in here" has cost me thousands. . .


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## ViperT4 (Jul 18, 2010)

Since the valves were hitting you should probably take them out and make sure they're still straight as well. Since the heads will be bare and off you might as well port them to match a cam.


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## svede1212 (Nov 1, 2005)

ViperT4 said:


> Since the valves were hitting you should probably take them out and make sure they're still straight as well. Since the heads will be bare and off you might as well port them to match a cam.


To be thorough you're right. Just from looking at the pic if that's the hardest hit piston they'll probably be OK. I was going to suggest a nice milling seeing the cam is now going in. 11:1 compression?


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## amdoverclocker (Dec 21, 2010)

I had to decide against a cam swap. I just have too much to do that there is no money for it. The cam itself isn't all that bad but plus $450 to get a tune kinda hurts. I still need to replace the clutch and rebuild the trans.. not cheap. I just finished paying off my suspension not all that long ago. All of my stuff will be at my house tomorrow by 10AM so I'll get started tomorrow night.


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## GTPpower (Aug 1, 2012)

svede1212 said:


> "while I'm in here" has cost me thousands. . .


:lol:


You aren't the only one.:cheers


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## ViperT4 (Jul 18, 2010)

Yeah, I figured that was the answer. I was just going along with the "since you're in there" theme.

I stand by the first half of my post though. You're going to want to verify in some way that your valves are still good and not leaking. Minimally the water test- pour some water into the intake/exhaust ports and see if any trickles past the valve into the combustion chamber side. If you can do the work yourself take the valves out and make sure they're all up to snuff.


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## amdoverclocker (Dec 21, 2010)

Humm okay, I'll give that a try Viper. Thanks!


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## GTPpower (Aug 1, 2012)

The last valve I had an issue with, I took to a machine shop. They put it in their valve grinding machine and spun it. It was easy to see that it was bent.


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## amdoverclocker (Dec 21, 2010)

She lives again! Everything is working perfectly except for the throttle cable. When it attached, it idles at 2500. When it taken off, its back to 750 or whatever. I didn't touch any of that mess. How can I adjust the cruse control cable? I took off the cover but couldn't see any obvious way of doing this. Thanks!

Edit: Never mind! The o-ring inside the last cable linkage is falling apart. It was stuck inside there. I freed it up and the cable went back to the correct length. Now shes perfect!


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## amdoverclocker (Dec 21, 2010)

I am highly impressed with myself. That was the first engine, well piston engine, that I've rebuilt. Everything went perfectly. No extra bolts or pieces missing. Thoughts on how long I should wait before I can get on it again? Summary of work: new lifters, push rods, push rod alignment plates, (head bolts, valley cover, head and valve cover) gaskets. Heads, pistons, and top of block were cleaned. I changed the oil today and am going to do it in another day or so. How long should I wait? Thanks for all the advice!


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## GTPpower (Aug 1, 2012)

I always make sure to get all the coolant out of the motor before getting on it at all. usually, I'll start it up, and let it idle for 30 minutes or so, while I'm adding coolant and getting all the air out of the system. Then, I will drain the oil and put new oil in. Then after 200-500 miles, I'll drain the oil again. If the drained oil doesn't throw any alarms to me, I'll hook the tuner and wideband up and proceed to tune it.


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