Valve Drop and Piston to Valve Clearance

furrystump said

I have done it when I changed from a hydr to solid lifter on the motor in the car. I was ASSURED it would ABSOLUTELY fit! I have trust issues, so I installed checker springs and a dial indicator on valve tip. Rotated the crank through a cycle stopping every 5 degs when the piston started to get closer to tdc. Push down on the valve tip to see what the tightest clearance was. They were right, there was PLENTY, but I could sleep easier checking. I would not approach the min. piston to valve clearance measuring this way. NOT precision, but worth it to me if I’m not pulling a head.

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You have made my point. You used checking springs so when you put the springs on you run you’ll have even more p/v. And you still don’t know what you have for clearance, or where that clearance is.

I’ve notched pistons because guys have used the valve drop/soft spring method that didn’t need it.

If the valve is hitting the notch (and it happens a lot) you think you don’t have enough notch depth, when in reality you have more than you need but the valve is hitting the notch.

That’s why you need to know how much clearance you have and where you have or you waste time and money and compression.

I’ll say it again, VOTDC and v/p isn’t enough information. It’s classic around this place to do sloppy work and claim it’s great. And the usual suspects are all blowing their own horns.

Correctly degreeing a cam and accurately measuring p/v is basic engine assembly. If you can’t do those simple things correctly, plus measure everything else with micrometers you shouldn’t be assembling engines.