Quote:
Will I need to have the seats machined down to give enough valve spring travel,
to determine if there is clearance between the bottom of the retainer and the top of the valve stem seal...
1) install a stem seal that will be used on the final head assembly
2) install a valve into that valve guide, again a valve that will be used in the final assembly
3) pull the valve into the valve close position and install the retainer that will be used and keepers that will be used in the final assembly
4) use one hand to pull up on the retainer to fully seat - close the valve
5) use a caliper in the other hand to measure the distance between the bottom of the retainer and the top of the stem seal.
the distance measure must be greater than the cam lift at the valve or the bottom of the retainer will crush into the top of the stem seal when the valve is open.
if the clearance is close, < .030, I would check all the valves as there will be some difference in the seat heights, depending upon the compentance and care of the person and machinery doing the valve seat work.
Your initial question may also have to do with coil bind,
I always re check that when manually rotating the engine during final engine assembly, but you don't want to find the issue then.
1) use a spring height tool.
https://www.summitracing.com/parts/sum- ... 29e8f8c24c
3) Install a valve, retainer keepers, use the tool to measure the installed valve height.
4) put the valve spring in a sturdy bench vise and compress the valve to the installed height. ( be careful to keep the valve in the vise)
5) compress the valve further to the valve open distance ( open height minus the cam lift at the valve)
6) verify clearance between the coils is at least .060,,, depending upon how the coils compress some coils may touch, that is ok, but the clearances that are available should be .060
or more with in reason. You definitely don't want the coils to go solid, but having crazy excess coil clearance ( .200) is not good either.
And lastly, concerning machining spring seats,, I buy springs that fit within my installed height to cam lift to coil bind requirements and are close on open / closed spring pressures then machine or shim the spring seats to get to the target for valve open-closed spring pressures.