Anyone know the absolute maximum OD size of a valve shim you can run without machine work. I was hoping to squeeze in a 1.48 OD shim.

 

And while we are talking shims, can you stack shims,

ex: use a .015 on top of a .030?

 

Well, I'm not certain on the max oem diameter. However, the Crane dual springs that many guys run are listed as springs for oem unmachined Lt1 heads and they have an spring OD of 1.46".

I have 1.50+ CompCams cupped spring seats for my set-up. They were a used set that were about 1.55" and I had them "polished" down to fit .But since my heads were CNC'd they may have expanded the spring pockets some too. It was too long ago and I don't recall if my pockets are oem sized.

 

I know the 1.46 OD springs will fit, i will be running the 1.46 OD K-motion springs.

I need to get about .045 shimmed up, so i am open on ideas (ie spring cups/seats/shims) on how to best do this without machine work. The heads are staying on the car. I wonder if i can just dremel a little out?

 

Well, I reduced the size of the spring seats/shims to ensure a flush fitting. Again, my seat cups were about 1.50" and fit well. I have heard of guys cutting and shaping the seats, but I'm not sure that is recommended. You can stack shims like a .030" and a .015", but I don't know how high one can go. I'm not sure if there is a limit to stacking. Maybe someone else will chime in.

 

Don-
Do you happen to know who made those 1.50 cups?

Can anyone tell me the exact (i mean you have it measured with a caliper) of the ID on an aluminum head LT1?

I know the OD is 1.46 or right there, but whats the inside. All the shims/cups etc are all too small it seams to fit over the OD of valve (the ID of the pocket).

 

i put a comp 987 spring kit on my car with the 1.5" OD locators without machining the heads. all i did was use a dremel and make some notches on the locator where it wouldnt set flat on the head seat. since the springs were only 1.46" OD they would fit fine but the locators were too large so i had room to work with. point is my car runs great just notching out the locator so im sure you can do the same with a shim.

 

They were Comps. My particular set were larger than 1.50". I was given a used set and had them machine "polished" down to fit. So they were a tad over 1.50 on mine.

 

Guys i would like to thank everyone for their help.

I finally found some shims that should fit the stock seat and dont cost $50 like crane wanted.

1.48 OD, .703 ID which will be a tight fit for my springs, but should work. I have meansured and remeasured. That is also as big as you can go from what i have found without doing a little dremeling or buffing out hte "terrain" on the heads.

Once again thanks!