I'm trying to verify that the cam/head combo I have will work short of turning the key and counting pieces coming out the exhaust. I just did the clay method real quick but the PTV clearance seems deceptively high. I know everyone mentions using a solid lifter to check PTV clearance but whats a brother to do when he does not have one? I have the old lifters that I'm not reusing but I couldn't find a guide on making them solid. The new lifters are morels and I'm not takin' them babies apart.

Clearance was approx .220" intake, .230" exhaust. Keep in mind the pistons are already flycut from the other set of heads to a peak depth of .125 intake, .100 exhaust. I did however notice that when I took the heads off the 2 lifters I had used for this test were sunken in as compared to the ones next to them that are brand new never used.

That much clearance just seems high on what should be a motor in the 11.6 CR ratio range with a pretty huge cam (a cam that replaced my "small" 244/248 .61x lift cam, the new one has longer durations and a little more lift as well). Now granted this could be me sucking at another form of measurement. I originally had LQ9 heads but swapped to LS3's, I measured the chamber volume of the LQ9's at 68cc and had the LS3's milled to the same. But, my measuring may be off and they may be milled less then the LQ9's. Also the LS3's were CNC ported and possibly had a valve job to increase PTV clearance a bit.



Sigh, should have just gone for 72cc chambers and a twin turbo setup.

 

I am still amazed that nobody has made a solid lifter to sell! I have heard that you can use your old lifter and weld it solid or remove the spring and cup/plunger and fill with washers - then put spring back on. This sounds simple but is not real easy!

Another way is to use real lightweight checking springs and a dial indicator. Check within 25 degrees on each side of TDC which is where you will be tightest. You can rotate the engine and with the indicator on the valve push the retainer down by hand until it hits and measure travel. With light springs you will most likely not be compressing the lifter.

 

Modifying the stock lifter is pretty straight forward. There’s a wire clip above the cup that you need to remove. Then use a magnet to suck out the guts, spring washers, etc. I prefer to use paste epoxy (JB Weld stick) to fill the void. Pack it in tight, then place the cup on top, with the retainer over. Let it set overnight to be sure it has hardened fully and you're good to go. Then gasp in amazement when you're clearance numbers drop drastically. :o

Those numbers are definitely off, even with stock pistons notched to the max, on an 11.6:1 motor there’s no way you have that much clearance. Where are you taking your measurements? 10* before and after TDC is where your clearance will be lowest. Keep in mind you still need to use a checker spring (light spring) and an adjustable pushrod set to zero lash. Also, most checker springs are stiff enough to compress a stock lifter, I'm not a fan of the clay method. Do it the right way...