when setting spring height on Edelbrock Performer RPM head for a big block, the set height is 1.800 . Is there a + - tolerance ?

Normally you just get it as close as you can given the shims are in .015" increments.

I set them +/- .005". Example; 1.785" gets .015" shim for 1.800". 1.790" gets .015" shim for 1.805". 1.800" gets no shim.you can mix and match .015",.030", .060" to get your desired heights.
Doug

That`s what we did on mine.............

And just as important is stem height.

I just shimmed a set of springs last weekend and I was able to get them all within +/-.010". Having a set of .060", .030", and .015" shims handy sure helped.

Before I started, I searched the internet and found some company's/people suggesting +/-.020" all the way down to +/-.005" on the installed height.

Your way better off to buy a valve spring pressure gauge, even a cheap one and then set pressures on the seats + or - 5 lbs and check open pressures as well and check for coil bind.
On a single spring with no inner spring like the ones used on most Eddy heads you can't swap the inner around to try and balance both the seat and open pressure but knowing there all within 5 lbs on the seats is a good start
On a stock type street flat tappet cam, solid or hydrauli lifters, I shoot for between 130 to 160 lbs on the seats and 325 to 350 lbs opened
I've seen springs that needed .060 shim to get them within 5 lbs of the others on the seats
I would go through all of them first to check the pressures at the same installed hieght and see which ones are the strongest ones and use them on the heavier intake valves and try and shim the rest of them to get all of them as close as you can to the strongest ones without them getting closer than .060 from coil bind

Jeff at Modern Cylinder Head set them up before he passed. There 1.5 dia. triple springs, don't know why he went that way on a solid lifter cam and I didn't get the info of the manufacture of the spring set so I don't know what the spec.'s should be. I don't have a spring pressure checker but from just going through a rough set up on one head I was getting around -.005 to a +.003 so I guess that's close enough. I'll check for coil bind also.

Those springs are probally a double spring with a flat dampener in between the inner and outer valve springs I'm sure Jeff set them up correclty for your cam type and lift, if you furnish him that information
Due to the differences in rocker arm and the ratio errors try and check for coil bind at max lift below the retainers on all the valve springs, all 16 of them I like to see minimum of .060 between the coils they will vary, I've seen some that had .060 in some places and .030 to .090 in other places on the same set

I generally get them as close as I can. But on most heads if you want them right on you can set them on the high side and then machine the difference of the spring seat as long as its a very small amount. Ron

I suggest getting all your springs tested so you have some idea what Jeff set them up to be. When it comes time to buy new springs, you will then have some idea. Too bad you did not get the spring part number(s).

Good thought!
A double spring with a damper.

They don't have to be perfect. Even with some of the highest quality springs out there the seat pressure can be +/- 20 or 30 lbs at exactly the same checking height.

Use a number that will put you close to the same seat pressure through out. The rate should keep it very close to the same on the nose, but check to be sure.

BTW....I would look deeper into the triple application for a flat tappet, whiles its possible to be the perfect spring, its a little iffy.....

.100" from coil bind is a good number to set your installed height at.....
( valve lift + spring coil bind =.... )- installed height= number from coil bind.....shim accordingly

I surely hope guys aren't going by the manufactures advertised spring height installed and advertised pressures. Each and every height should be measured and the springs set up on a calibrated spring pressure checker