pdd

iTrader: (3)

ok. brought the piston to top dead center. took the intake and exhaust valve springs off. pushed the valve all the way down and measured 70thousandths. brought the valve all the way up and measured 365 thousandths. so if i subtract the 365-70=295thousandths. is that right???thats only one side, still have to measure the other. but want to know if im on the right track.

66ImpalaLT1

Thats not P to V, thats valve drop at TDC. To measure P2V you need lightweight springs installed with the valvetrain, and then turn the engine until you find the least amount of drop. P2V is not checked at TDC. Minimum intake clearance is when the piston is moving down, minimum exhaust clearance is when the piston is moving up.

pdd

iTrader: (3)

ok. ordered up some light weight springs. ill give it another try when come in. thanks

66ImpalaLT1

I'm going to try and do it myself this weekend. My cam degree kit cam with springs that will work.

Jason99T/A

iTrader: (21)

You need to check PtV at 8* before TDC on the exhaust and 8* after TDC on the intake. This will generally be VERY close to your tighest point. I normally start at 10 before/after TDC and work in 2* increments towards TDC until the clearance starts to increase.

BLASTER

iTrader: (4)

I am wondering about this as well. Do you just install the springs on one I and E valve? If you have the light weight springs installed and you dial in the 10 before and after (I assume with a wheel) how do you take the measurement? Do degree kits come with this setup? Thanks

PREDATOR-Z

Your not checking the PtoV clearance at max lift, you need to check it during the camshaft overlap period. For instance if your checking cylinder #1 your overlap would be really close to where the timing chain dots line up. You set the valvetrain to zero lash with both valves closed, your cam gear timing mark will be at 12 o clock, overlap occurs 360 crank degrees from that, or 180 cam degrees, so overlap would be when the upper timing gear is at 6 o clock. Check intake and exhaust 10 degrees before TDC and 10 degrees after TDC during overlap and everywhere in between.

I usually put the dial indicator against a retainer and have it clamped to a long metric bolt using rocker arm threads, usually from the next cylinder over (#3). You zero the guage when you make piston contact with the valve by pushing the valve open, then when you let it go, that reading is your clearance.


Tools needed:
1-dial indicator
2-very light valve spring int/exhaust (to get a more accurate reading)