Ive got a 2003 UC torn down to do a 95" BB on. Its had some mild headwork done. The intake valve is larger and some porting. The heads have had 20 thou shaved off and Ive got a 40 thou cometic head gasket to install. For the BB I will be using SE flat tops and will stay with the cams already in the bike. They are S&S 510G's. Do you think I need to check valve to piston clearance here? Id expect that I'll have plenty of room with only 20 thou shaved off and only .510 lift but the larger valve is where I am a little concerned. If you think I should check the clearance, what is the easiest way? I was thinking a little moddeling clay and mock eveything up and set the pushrods at zero lash (the zero lash would be worst case scenario if trying to imitate a valve being floated) and roll the motor over by hand. I do not have a set of solid lifters. How would you pros do it? Thanks for the feedback.

 

I think I would look at the valve to valve clearance before I would worry about valve to piston clearance with a set of 510 lift cams.

 

.510 lift cams aren't that much lift. The bike has already been running fine as an 88" with these cams. Thanks for the input, just dont think it will be neccesary to do that.

 

[QUOTE=1931jamesw; If you think I should check the clearance, what is the easiest way? I was thinking a little moddeling clay and mock eveything up and set the pushrods at zero lash (the zero lash would be worst case scenario if trying to imitate a valve being floated) and roll the motor over by hand. I do not have a set of solid lifters. How would you pros do it? Thanks for the feedback.[/QUOTE]
Go to YouTube TheKingOfCubes Channel and watch Performance Package Install.

 

The .510" lift is not the crtical factor; TDC lift is where you need to measure. Randy's video covers it all; very helpful but the heads are disassembled in the video. If your heads are disassembled or you have the valve spring comressor, dial dept guage, a good set of calipers and Randy's locking collars, you are set.

However, you can check the valve to piston clearance and quench with the assembled heads by putting the clay in the proper places per Randy's video; have done it many times. Valve to valve clearance is not an issue but if you want to check that dimension, you will need to disassemble the heads or use Trock tool to open the valves to TDC lift and check them that way.

You could have the valve reliefs opened up to accomodate the larger valves per the attached photo. Or, you can follow Randy's video and check the valve to piston clearance at the valve relief and the area between the outer edge of the valve relief and the edge of the piston. A set of hydraulics won't work because the lifter plunger will travel and the reading will be off. If you have a set of old lifters, take them apart, toss the spring, turn the plunger upside down and reinstall the pushrod cup; they will act as solids. Or, go to Autozone and pickup a set of solid roller lifters for a small block Chevy for about $8/each.

Be careful rolling the motor over and if you feel solid resistance, stop. That should not happen but, if it does, it means you probably adjusted the pushrods wrong; bad juju and easy to bend a valve. Set pushrods at 0 lash with the piston at TDC on the compression stroke. Torque the heads per spec to check.

Some guys use solder to check quench and V to P clearance; I have used .060" solder and I like it better than clay because I find it easier to handle and measure. Some will tell you solder is no good, piston rocks, etc, but since it's not aero space stuff, I don't worry if the measurements are off .001; close enough for me. Placing the clay in the freezer for a while makes it a bit easier to work with and less likely to deform when you are handling it.

Good luck!

 

the .510 only has around .180 TDC,you wount have any valve to valve or valve to piston clearance probs.if you want to check,the easiest way without useing clay(we`ve seen guys bend valves useing clay).remove the springs and mark valve stems with dykem (or a majic marker)get valve closed on seat and mark the TDC lift + .060 on the stem,measure off the seal.open both valves to mark to check valve to valve,then put head on cylinder,snug 2 head bolts and crank motor useing rear wheel in 5 gear,if either valve moves up,you have contact,if not your good to go