Of the different brands of micrometers out there for checking the installed height of valve springs, which one is the best. Where it is made does matter, US vs China.

If your going too install by height versus pressure then any thing close will work
To install by height you should buy either a decent set of inside calipers or a height mike so you can shim each spring to the same height within .005 or so
The better choice is to purchase a vice type valve spring tester and a height mike so you can shim each spring to the same pressures, + or- 5.0 Lbs. on the seats

I just use the Summit height tool plus I do spring pressure also..
been fine to 8500+ rpm

To take it a step further, what is the latest thought on room to coil bind? I have heard more than.060 but less than .100, and if the spring is short on load in that range, a different spring is needed. Having more seat pressure than planned is much less of a problem.

I've been told by some racers that revved the heck(9000+ RPM) out of there motors that have a lot of spring pressure(above 900+ Lbs. over the nose) to use .050 with checking springs for coil bind
I use .060 to .080 for coil bind with checking springs and have for years on any of my motors that will be revved above 5000 RPM street or race only

Running close to coil bind is to crush harmonics out of the spring cycle, and often just a necessity of room under the retainer . The goal, changes where, and what you set up. Spring longevity, and performance, are two different goals. High HP na goal engines run really high intake pressures, and very low exhaust pressure as one example. I've seen longevity goal run a 2.3 set up spring where 2.1 would have worked at near coil bind. The cam never challenges the spring, Not enough action to start a harmonic, and they go 200 passes on what would be 50 at 2.1. They do pay for it in needing high quality valve gear.

dthemi & polyspheric,

Aren't the stock springs with the stock cams not anywhere close to coil bind ? As far as crushing or
suppressing the harmonics (Slinky effect), isn't that what the flat wound dampener is supposed to do ?
I have read what I could find about operating springs near coil bind, but I can't say I'm convinced.
I always thought coil springs were less stressed and longer lived if they operate at only a fraction
of their linear operating range.

Stock cams are so mild, and the springs so weak it hardly matters. Yes, the dampers in springs is to help control them. The valve springs in stock motors from "the day" were the final rev limiter.

The flat wound dampers in stock type springs don't work in, and there's no room for them in a race application.

Guys, I just wanted to know which brand.

Starrett, Craftsman, some others I can't remember now and Mititoyo is what I use and have now on micrometers, both inside and outside
there are a lot of other good brands out there also, the big thing is to have the set up standards and use them to insure the accuracy of each gauge

The ones from PAC are pretty nice.

I just use a snap gauge and a digital caliper. A spring micrometer may be a little more accurate, but I just don't like wasting the time to spin it out and back. A weak spring and a snap gauge is fast and accurate. Plus very cheap.


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What is a snap gauge? Are the ones from ProForm any good?

That answer would be PAC. Twice as much as others, 100% quality piece.

also, don't forget :
use them with CARE. don't pick them up to use with gritty, greasy hands. this also helps keep you from dropping them.

store them as SURGICAL INSTRUMENTS. don't just toss 'em in your box. quality measuring instruments come in a storage container. that is where they belong.

keep them CLEAN. gently wipe them clean after each use, and use the appropriate lubricant at the recommended intervals.

do this, and these tools will repeat measurements every time and last several lifetimes.

I like the style that expands under the retainer since it gives you a very accurate reading. The old school way is with a spring loaded tool that you then measure with a mic or caliper.

https://www.summitracing.com/parts/pro-66902

It is shaped like a tee and when you twist the handle it locks the measurement you have, They have a weak spring inside the tool, so you hold the retainer up snap the tool to record the measurement, and then lock it, and then measure with a dial caliper. Also works to measure cylinder bores, main and rod bearing bores, etc. Every engine builder should have one.
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Proform ones would be fine.

Ok, I know what you are talking about. Are the ProForm mikes any good?

There are reviews on each one that Summit sells just follow the link Andy posted. Seems like the PAC unit is very nice and the others will do the job but I would check them against a known micrometer

Gus