Community Q&A Question: Piston to valve clearance

Asking About: Mustang Scat 331 Stroker Kit - Flat Top Pistons, I Beam Rods (79-95)


Piston to valve clearance

what is the best way to measure for piston to valve clearance? Will my cam card give me that information?
from elsmere |
0 0

Unfortunately your cam card will not tell you piston to valve clearance. Basically you have to partially assemble the motor to check piston to valve clearance. the most common procedure is as follows: Once you have your rotating assembly installed, you will install your camshaft and degree it to the proper specs listed on your cam card. Once the cam is degree'd in correctly you will bring number one cylinder up to top dead center "TDC". Install some modelers clay, play dough etc on the piston where the valve reliefs would go and make sure it is flattened out evenly. You will also need a pair of Solid lifters "they also make check lifters or check springs for this as well" to install on the cylinder you are working on. Hydraulic lifter will not work because they will compress. Next you will put on the head without the head gasket and torque it down. install your push rods and rocker arm and tighten them down to spec. Next you will slowly "and i emphasize slowly rotate the motor over to see if the valves come into contact with the piston. If it comes into contact, you will need to change cams, notch your current pistons or get a new set to allow for proper clearance. if it does not com into contact, pull the head back off and you will see the indention of the valve in the putty., carefully cut the putty in half as to not distort any of the thickness and measure the distance from the base of the valve indention the the surface of the valve relief. now take that measurement and add the thickness of your compressed head gasket and that will give you the piston to valve clearance you have on your combination. Its a pretty time consuming task and we recommend having a machine shop or reputable engine builder to assemble and verify all clearances on any performance build.
from hewitt |
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