i just spend a good part of an hour searching and reading threw threads. so here is my question...

i might have a deal on a set of afr 205's. and i want to run the torquer v2 cam. with this heads/cam would it be possible to reach 11:1 dcr and still have good valve to piston clearance?

also if i dont get the afr's i might just get a set of ls6 heads and get them ported. would it be possible to reach 11:1 dcr and still be safe?

how do i go about doing this?

 

11:1 DCR, lol. I think you mean SCR

What you can do is clay the engine. What they do is put clay on the piston top, instaklle the heads and crack the engine by hand a few times. Then they take the clay out and can measure it to see how close the valve came to the piston. Then from there you can determine how much you can mill.

I have been trying to find people that milled down their 5.3 heads but it looks like I am gonna have to clay mine too.

 

well, im goin through this now, and there's a little more to it. you'll need a set of 2 solid roller lifters and would be best to use checking springs instead of normal springs if you have them. if you dont use solid lifters, the valve in the lifter will drain of its oil and just compress, and it'll give you a false reading that will show up as more clearance then you have. I think Ive read somewhere on here that the valve in the lifter has .200 of travel, and typical lash will be in the .080-.100 range. meaning if the lifter bleeds down while your rotating the engine due to spring pressure, along with the pressure of squeezing the clay, will not be accurate.
that said, Im pretty sure that with my solid lifter (I got some stock lifters cheap and took them apart and filled them with epoxy, and reassembled them before they cured), since its now locked in the full up position, no preload, I can add the .080" preload I plan on running to the thickness of the clay under the valve (after I flycut my pistons due to my combo.).
I bought a set of lifters off a fellow board member, and did the whole set up to sell the rest if your interested. real cheap not trying to make money. $10 plus shipping for two. let me know.

there is another way though, and I believe would be the better way. I'll repost a link to a thread I started where people explained how this works. but it involves using a degree wheel, and dial indicator to check manually at various degree's to locate the point in degree's at which the valve is closest to the piston, and there you can see exactly how much clearance you have. all cams will be different since the cams opening/closing points are what determines how much and where the closest point will be.

 

i like your lifter epoxy idea, that gets the potential pushing of the roller out of the equation. The only issue i see is if when fully out it causes you to actually hit the valve, then you wont know how much you could really mill.

 

I'm just going to throw this out there for the hell of it... The way I have always checked the p/v clearance was to remove the valve springs, wrap a rubber band around the 2 valves so they can not fall completely down, adjust the valve lash to 0 (in the past I always used a solid lifter as well, but since there is no real pressure on the lifter you could accomplish it with a stock hydraulic, you would just have to add your lifter preload amount to the clearance value you come up with to determine actual running p/v clearance) turn the motor over. When you see the pist start to push the valve up as the rocker moves down, watch it until they reach their closest point, then back it up a little, pull out your trusty feeler gauges and start measuring. Slowly rotate the motor until you find the smallest feeler gauge that fits snugly between the rocker and valve tip, this is your p/v clearance with the lifter at 0 lash, addd your preload and there you go.

 

that makes sense. just make sure to measure at several spots to ensure you found the tightest spot.

 

The accurate way to do it is with a dial, soft springs and modified solid roller. Clay is ballpark at best and needs true clay and not playdough.

 

I couldnt agree more, I cringed just a little bit when i saw a chevy high performance article actually suggest that you use playdoh. The push indicator is the most accurate method by far IMO.