claying for p/v clearance
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TECH Junkie
Joined: Nov 2001
Posts: 3,604
Likes: 0
From: Los Angeles
claying for p/v clearance Never done this before, but since I have the car all apart with a new cam in I'm gonna stick a head on and rotate the crank.
couple questions.
1) Doing just the #1 cylinder intake valve will be enough right? No need to put on the other head and check the psg side at all (ie, if one lobe is good, they'll all be good)
2) does it matter what clay I use? I was gonna use my zaino claybar in the cylinder, rotate the crank 720 degrees, then cut it with a knife after it gets smashed and measure the cross section where the valve compressed it. Is this the proper method?
couple questions.
1) Doing just the #1 cylinder intake valve will be enough right? No need to put on the other head and check the psg side at all (ie, if one lobe is good, they'll all be good)
2) does it matter what clay I use? I was gonna use my zaino claybar in the cylinder, rotate the crank 720 degrees, then cut it with a knife after it gets smashed and measure the cross section where the valve compressed it. Is this the proper method?
Teching In
Joined: Jul 2002
Posts: 25
Likes: 0
From: Nixa, Mo. USA
Re: claying for p/v clearance Back in the old days when I did this on small blocks I would use modeling clay (like kids use) and put thin amount on piston with clear celophane paper on clay so it would not end up stuck to head or valves (Saran Wrap). Soft checking springs would keep hydraulic lifters from bleeding down too. Just my $.02 worth.
Re: claying for p/v clearance I read an article not too long ago about claying the motor (found it searching on google). It said to use modeling clay as well, but not to use playdoh (or any other "spongy" material. IIRC, the zaino claybars will rise back up after pressing in on it). I figure that if you do one piston and check both the exhaust and intake valves, then it all should be fine. But I believe the article said to do all the cylinders.
The Bull
Joined: Jun 2002
Posts: 3,578
Likes: 2
From: Grand Rapids, MI
Re: claying for p/v clearance I did mine when I did the head/cam install. I used molding clay from Hobby Lobby (my mom out of all people knew where to find that stuff). It's very soft but releases easy. It cures under heat, so when the engine fires up the little stuff that you miss will turn into crusty **** and blow out the exhaust. You may want to coat the valves with a little vasoline so that the cold valve doesn't stick to the clay.
I just did cylinder 1 and made sure I put all of the surrounding bolts in. You may want to paritally tighten the bolts in the middle of the block by cylinder 3 a little as well, but it shouldn't matter.
My cam has a .581 lift on a 224/224 114LSA and I didn't even get a ding in the clay. Keep in mind that doing this by hand (I used a starter trigger to do it a lot faster) will not give you a measurement on the acceleration side where you may get some slight hesitation from the valve springs snapping shut. I'm not quite sure how close to measure the distance the valves come in that case.
Hope that helps.
I just did cylinder 1 and made sure I put all of the surrounding bolts in. You may want to paritally tighten the bolts in the middle of the block by cylinder 3 a little as well, but it shouldn't matter.
My cam has a .581 lift on a 224/224 114LSA and I didn't even get a ding in the clay. Keep in mind that doing this by hand (I used a starter trigger to do it a lot faster) will not give you a measurement on the acceleration side where you may get some slight hesitation from the valve springs snapping shut. I'm not quite sure how close to measure the distance the valves come in that case.
Hope that helps.
