Kind of like what carpenters always say...........measure twice, cut once!Bullitt makes a good point-but it's always a good precaution/idea to check clearance regardless of what "should" fit without interference...
As for measuring p/v clearance...if you dial indicator the clearance and determine it to be within acceptable tolerance, you don't need to clay it...The dial is more precise anyway.
[/quote]If you want to run rollers in a flat tappet block, your only real option is to run retro fit link-bar lifters. DO NOT run a reduced base circle cam. Talk to any good cam grinder, they all hate reduced base circle cams.
The dial may give you a more exact measurement, but IMO clay is the better method. While clay may not give you an exact measurement down to the last .001", it does give you an idea of what your valve radial clearance is, which is something that the dial won't do. Plus the clay method is so mindlessly easy, anybody can do it without special tools, and you can generally get a measurement within +/- 5 or 10 thou, which is close enough to know if you have the proper clearance or not.
To the OP: Always, always, always check, regardless of what method you use! Here is a brief how-to of the clay method that I used while building my motor. If you have any questions, shoot me a PM.
http://www.stangnet.com/mustang-forums/threads/checking-piston-to-valve-clearance.837135/
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Please notice I didn't say the reduced base circle cam was a good idea, just the other method...
Also, I can't personally think of a time where the radial clearance will be less than the edge clearance unless the valve reliefs aren't cut evenly; which is a possibility. If the radial area of the valve is nearer to the piston than the edge, then the valve will run into the reliefs first and you'll still get your measurement by using the dial and checking spring, thereby negating the need for clay. I used the clay method numerous times and it does work-not saying it doesn't, and if you don't have the dial, it works fine. If you have the dial indicator though, there's no need to pull the heads off again just to measure a squished piece of modelers clay. JMO...
Yea I understood you on the cam thing, I just wanted to make it clear for the OP.
As for PtV, valves and valve notches are never in exactly the same place unless the pistons are designed for the specific heads or your machinist cut the notches for your setup. In a worse case scenario, you could have. 005" radial clearance with the sidewall of the notch, but you'd never know because the dial method only checks clearance parallel to the travel of the valve (axial). What happens when you run that motor and parts start to warm up and move around?
I just prefer the clay method because it gives you a 3D image of what is going on in the combustion chamber. The dial method only gives you part of the story.
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