Marks on the pistons from the valves hitting....
Thread Starter
TECH Senior Member
Joined: Nov 2001
Posts: 11,603
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From: Chi-Town, IL
Marks on the pistons from the valves hitting.... There are thumbnail size marks on each piston from the valves hitting...I was running an X1 cam before, was told I wouldn't have P to V clearance issues with this, but guess that wasn't true...
How much would these marks attract hot spots, and how much would those marks attract detonation?
TEA S2 5.7L 73cc heads will be put on next week, along with cometic gaskets and breather valves, my compression will be 9.5:1 and will be on 93 octane...
Help..
Thanks,
Bos
How much would these marks attract hot spots, and how much would those marks attract detonation?
TEA S2 5.7L 73cc heads will be put on next week, along with cometic gaskets and breather valves, my compression will be 9.5:1 and will be on 93 octane...
Help..
Thanks,
Bos
Re: Marks on the pistons from the valves hitting.... I usually don't like to tell people to remove piston material while in the motor. Can do more harm than good.
But if you can use a strong vaccuum to suck up particles as you smooth them It should be fine.
But if you can use a strong vaccuum to suck up particles as you smooth them It should be fine.
Re: Marks on the pistons from the valves hitting.... shouldnt be a problem, guess you lowered your compression a little <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
TECH Fanatic
Joined: Mar 2002
Posts: 1,044
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Re: Marks on the pistons from the valves hitting.... Use a round metal burr for aluminum, bring each piston to TDC and put a dab of grease around the gap between the piston and cylinder. When you're done, turn the motor to bring the piston down the bore and the grease will stay at the top along with any debris. I've done this, and actually fly-cut pistons on more engines than I can count and have never had any problem. Remember, the aluminum chips will melt or get blown out the exhaust. The real danger lies in allowing a chip to get lodged in a piston ring land, so DO NOT use compressed air to "clean up" a cylinder! Always use a shop vac to remove any debris. Even a soft piece of gasket can destroy a cylinder if it gets under the ring land...
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On The Tree
Joined: Jan 2003
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From: in the air of course!
Re: Marks on the pistons from the valves hitting.... yup, PTV is close on that cam WITHOUT milling the heads. Yours were apparently milled 30.
You are loosing mucho HP there. It would be tough to say if you have a strait valve in that motor <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
You are loosing mucho HP there. It would be tough to say if you have a strait valve in that motor <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
TECH Fanatic
Joined: Nov 2001
Posts: 1,986
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From: Centrifugal City
Re: Marks on the pistons from the valves hitting.... Assuming you've checked/fixed the valves and inspected the seats, right?
<img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
<img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
TECH Enthusiast
Joined: Nov 2001
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From: IL
Re: Marks on the pistons from the valves hitting.... Yes Bos had his heads and valve seats checked out prior to selling them.
Since then he's bought a set of new TEA Stage 2 5.7L (73cc chambers) to help lower his compression a bit.
Since then he's bought a set of new TEA Stage 2 5.7L (73cc chambers) to help lower his compression a bit.
Thread Starter
TECH Senior Member
Joined: Nov 2001
Posts: 11,603
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From: Chi-Town, IL
Re: Marks on the pistons from the valves hitting.... The heads I sold are ok, the only way I can think of that happening was when I slammed the rev limiter....which is 7000 in my car....sometimes when you spin it catches you off guard... <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
