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Discussion Starter · #1 ·
Hi Guys,

Much against my own desires I followed the advice here and got myself some AFR enforcer heads instead of the ( and I quote) paperweight original iron heads .

I already had VS380 valve springs from melling for my cam together with valves etc etc.
I have aluminium heads now, so I will need something steelt to prevent tearing up the valve spring seat.

My question is: can I use just a 15 thou shim, 1.55" diameter that fits snuggly in the 1.55" valve spring seat on the head?
Or do I need to find a valve spring cup/locator to also locate the spring on the bottom? This would give me a perfect installed height.

The VS380 springs are a 1.22-1.23" OD spring with damper.

Thanks in advance!
 

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Race it, Don't rice it!
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You need a cup under spring. The cup locates the spring and keeps it from moving all around. The ID of the cup should be .005ish of the guide boss. The OD of the cup should be .005ish of the spring.
Shims go under the cup to squish the springs to the desired closed pressure.

If you're springs were 1.55 you can get away without the cup and just the spring and shim and let the head casting do the locating. Because your springs are smaller, you'll need a locator.
 

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My preference is a locator or a cup. A shim has comparatively sharp edges that as the spring moves the shim about will cut into the softer metals. Locators and cups use a collar in the case of locators or an o.d. raised edge in the case of cups which spread the slide loads introduced by the spring over a wider surface so the softer metals are not damaged by the locator or cup.

In reality GM uses a shim under factory aluminum head’s but they use a cast iron guide rather than bronze so where their shim centers on the guide is a hard wearing item against another hard wearing item in terms of how they interface. So it is important to consider the mating materials wear characteristics which in iron or steel the knife edge wear surface is well resisted and iron also provides excellent longitudinal wear characteristics for the reciprocating motion of the valve stem. Bronze more commonly found with aftermarket head’s has excellent wear characteristics for the valve stem motion but is not as resistant to “cutting” forces as would be seen as the edge load of a steel shim.

Unless there is a need to be on the spring’s factory or spec installed height the locator or cup isn’t so thick as to abnormally upset toward the high side pressure of the spring. As long as at full lift you have a minimum of .050 inch clearance between the major coils your fine. If there is a need to be “balls-on” with the spring height then the spring pad needs to be machined. Or you can use on offset lock that allows the retainer to sit higher. These are available usually in plus or minus .050 of the OEM position. These are easier to find for regular producrion barrel shape springs and their retainers than for beehives.

This all falls back on the issues of building a hot rod or competition engine to where the chain of mods and adjustments is seemingly endless. Depending on what you're building you just have to draw a circle around what you think is reasonable and go with the compromises you have to make for whatever reason from schedule, financial or technical.

This is an excellent catch on your part all of us having ended up loosing some sweat over this issue.


Bogie
 

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My preference is off the valve guide but that requires a tall enough guide to accommodate clearance to the retainer with enough space remaining for the seal and the locator’s collar, thus the need to do some mock-ups and measure things first. If there isn’t enough space then you’ll need to use a cup.

As BOOT points out the locator or the cup is not tightly anchored they do move about a bit but the saving grace is the loads are spread over a lot more area of the spring pocket. You want either to fit closely over the guide and in the case of the cup inside the outside diameter of the machined spring pad. So you need to go through the lists of these things to select what fits your head’s. I recommend you get a paper catalog from Competition Products as they reduce this to tables which is a lot easier that what you find on the web.


What you will find on their sight is shims, cups, locators and tools at this link:

Bogie
 

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Apparently the same guy that packages hot dogs and hot dog buns is the same guy that makes valve spring pockets and valve spring locators.

Bogie
When I was looking into upgrading the springs on stock Vortec heads several years ago, I noticed a kit from the A-parts guy that was priced very low, but I could not determine how he met that price point using the parts I knew were available. So I ended up buying quality parts from GMPP and CompCams.

I later read a post from a guy who bought the cheap kit and said some of the parts (I forget which ones) had been filed to fit. (edit: ground to fit.) 😲 Also, some sellers of low-priced valve spring kits advertise max lift at the point of coil bind! I would simply runaway, runaway from most of those eBay stores.

I second Bogie's suggestion to buy from Competition Products. Good valve spring kits at fair prices.
 

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Discussion Starter · #15 ·
So, my monkey brain only measured the top of the valve guides. Top is .500, bottom is .550
How hard is it to drill valve spring locators? Looks like there is enough meat to drill them out. Will a cobalt drill survive 16 seats? Or should I look into a carbide drill?
 

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A lathe would make short work if that problem.
without one, or one nearby, it’ll be time/money ahead to exchange them.
Using a drill bit, you’ll need a metric quality cobalt in 14mm.
 

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Discussion Starter · #20 ·
A lathe would make short work if that problem.
without one, or one nearby, it’ll be time/money ahead to exchange them.
Using a drill bit, you’ll need a metric quality cobalt in 14mm.
I'd exchange them or save them and buy the correct ones OR use a cutter that I already have to cut the guides to .500

What cost more the exchange shipping, m-shop cost or drill bits?
If cobalt works then I'll easily drill them, depending on how quick the cobalt wears
Exchange shipping is 50-60$ + new parts with 50-60$ shipping as well. Couldn't find a .550 locator either
 
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