Preassembly process for Piston to Valve clearance check

[Dauner]

Hi everyone,

Car is 89 911 Carrrera 3.2. Bored cylinders to 3.4 and went with JE pistons. No machining on heads that affect heights. No machining on cylinders that affect heights. No machining on case halves. EBS "sport cam" DC15 grind on camshafts. I checked deck height and came up with ~ 0.028", so ordered a set of 0.020" shims from EBS to get to a more comfortable 0.048" or 1.22mm. Doing some preplanning questions in case I get to the point of starting the preassembly Piston to Valve clearance check this weekend. A couple of questions:

1. No adhesives or sealants during this process

2. Piston pin circlips: I am only planning on installing the one right side circlip for the PTV check process. Reasoning is in case I need to remove piston due to clearance issues. I'll just install the left side clips on final assembly.

3. Cylinder base gasket sealant: knowing that I am using two gaskets, I am planning to put sealant on. My thinking is more opportunities for leaks. My concern is in clock time between pushing first cylinder down tight on base gaskets and torquing the last head stud nut. Tremendous amount of work to do within the 45 minutes for a first timer. Does Curil T afford more time? Seems like professionals suggest an adhesive / sealer not absolutely necessary. In July of 2019, what is conventional wisdom knowing I have two gaskets per cylinder?

4. Oil return tubes: not planning to install oil return tubes during this process. They are "floating" anyway. My thinking is why risk doing any kind of damage to the orings when I have to take it apart again anyway.

5. Clearance check process: Seems like there are three main methods mentioned. Neil Harvey's process of removing valve springs (I had my heads built by Steve at Headwerks and don't plan to fiddle with things by buying more tools and removing springs), Wayne's process of sweeping thru the full lobes and "mapping" the clearance or at least verifying can turn screws 1.5mm and 2mm on intake and exhaust, and the third process of just setting the valves to zero gap, turning adjusting screws 1.5 I and 2 E turns and just spinning crankshaft carefully while testing for any resistance. Process 3 seems fastest and easiest. Any benefit to process 2?

Thanks in advance!

Mark

[Neil Harvey]

Mark,

If you are going to do a dry build, then assemble the engine without any glue or clips.

There are many ways to achieve the result you want. The main thing is you understand what you are doing.

My way of checking P/V is when you have some unknowns. New piston, new camshaft or new valve timing. We do it this way, so that any changes can be made and the clearances calculated without any further checking. If you think you may change the camshafts or the valve timing after some use, then this way is a good way of knowing your limits.

If you are building an engine with known parts and known valve timing, then the rocker arm adjustment way is probably all you need to do. But turn the engine slowly up to and through TDC in case you do have some contact. I have no idea what the piston, camshaft or the timing used here is, so caution is a good friend to have.