how to check piston to valve clearance?

[DarkoStoj]

I bought a 2nd had rebuilt 351w shortblock, and I want to run a larger cam. I know the piston is a flat top with 4 2cc valve releifs. I am running 2.02/1.6 world windsor sr. heads, and I want to make sure the cam I order will work without hitting the pistons. What is the best way about figuring out whats the biggest lift cam I can run w/o hitting pistons?

 

[LMan]

http://www.fordmuscle.com/fundamentals/pistontovalve/index.shtml

btw, the 'biggest' cam isnt always the 'best' cam or the 'fastest' cam

 

[DarkoStoj]

http://www.fordmuscle.com/fundamentals/pistontovalve/index.shtml

btw, the 'biggest' cam isnt always the 'best' cam or the 'fastest' cam

well I plan on going ~.6's of lift, and I just want to make sure I won't have clearance problems

 

[69Rcode_Mach1]

You can always use the clay method it is very easy. Just install the cam, line up the timing marks with crank, install a piston into the block, coat the valve reliefs with some oil (So the clay won't stickand ruin accuracy of reading), put two small pieces of clay in the valve reliefs, put the cylinder head on, now if you have a hydraulic cam insert solid lifters into the corresponding bores(a regular hydraulic lifter will collapse so you must use or make a solid lifter, I made two with JB weld), put the cylinder head on with rocker arms, then crank the engine over a couple of times, and then take everything off along with the clay CAREFULLY and measure it with a micrometer and there you go you have your clearance. Or you can also do it with a magnetic base and dial indicator to measure valve travel.

 

[brianj5600]

How much .050 duration? I like to use soft springs and a dial indicator. You can do it w/o removing heads, unless they are too close.

 

[Hack]

how to check valve clearance

Here's another viewpoint.

http://www.rehermorrison.com/techTalk/41.htm

 

[brianj5600]

I wonder if their .025 to.30 extra with the real springs holds true for a mortal .600 cam and dual spring vs the monster cams and springs they use? The method they describe for radial clearance will only work wth domed pistons. Clay might be needed for radil clearance on a flattop.

 

[bnickel]

i've said it before and i'll say it again, the lift you are talking about with flat tops will have clearance issues. mid .500's is about max and that's questionable even depending on the duration @.050