sandman92084

I recently got a set of factory L31 vortec heads from a friend of a friend. They came with a set of LS6 valve springs and the comp 787-16 retainers to use them with the stock valves. He tried installing the springs and the I.D. was slightly too small and hit the valve guide bosses and would not seat all the way so he bought the comp cams 4716 valve seat cutter to machine them down to fit. My issue is when I measure with my valve spring mic I'm reading 1.880" install height but from what I have read these springs need to be at 1.750". The O.D. of the seat was cut to 1.320" and I.D. of the guide boss is now .630". I have looked without any luck but need to find a spring locator and shims to make this work or any other suggestions to get these heads finished.

sofakingdom

iTrader: (1)

AFAIK there's no spring seat that will fit that combination of sizes; but it wouldn't be too hard to get to a point where there IS one available.

What's the ID of the spring at the seat?

skinny z

If I recall correctly, the Vortec has a 1.7" install height on the springs. That's with stock retainers and keepers.
If the valves are stock, the retainers (I doubt) will add a 1/10th plus to overall height.
When you measure the height and get 1.880", what exactly are you measuring? Did you cut into the spring seat as well as the O.D. of the guide?

sandman92084

The outside of the guide boss was cut down to .630" but I think I did type I.D. earlier. I don't think he cut into the head casting at the seat because the seat is still level with the head. They're not recessed with any kind of lip or edge like I think it would have done if it had cut down too far. I had measured the install height with a valve spring mic and I was real surprised to see more than a tenth higher than I expected too. When I get home later I'll check the mic with my calipers to be sure they're accurate and I'll measure the I.D. of the springs. I also have the stock springs and retainers and a set of lunati 73943 springs and retainers I can check their install height too maybe the comp retainers for the LS beehives just add a lot of extra clearance.

skinny z

I suppose there's every possibility that the valves aren't stock. Perhaps a quick measurement of those will tell that tale.

sofakingdom

iTrader: (1)

That tool should have cut the guides to .630" OD... ID should have remained stock, at .34375".

If memory serves the OD of that spring is around 1.280"; in which case, the 1.320" pockets you have now, should be OK. Problem is, I don't know of any spring thingies of any sort to fit a .630" ID guide, with anything other than big block sized OD springs. (1.550" ±) None of em fit the combo of 1.320" pocket and .630" guide.

Wouldn't be too hard though, to cut the guide down to one of the standard SBC sizes (.500" or .530", probably .530"); use spring seats for that; and .530" Teflon seals. Which guide size to use will depend on the spring ID, since if memory serves, the OD of the center parts of the spring thingy, i.e. the ID of the spring it will match the best, is dependent on the guide OD, i.e. the ID of the spring you want to use. So, get the ID of your springs, then we can pick the right other parts to go with them.

Doesn't too much matter whether the valves are stock or not, although ideally they aren't. Not aholehelluvalotta sense in putting all this effort into it and leaving that garbage sitting there, after all. But regardless, just use your valve spring mic to see what you've got once you get the spring seats in place, and then select shims or offset keepers to get to the installed height the springs want.

skinny z

Might be some further information here. Seems from other's experiences, the LS6 springs should fit the Vortec heads with zero mdoifications....

https://www.thirdgen.org/forums/tech...nning-ls6.html

https://www.thirdgen.org/forums/tech...ortec-lt4.html

For what it's worth, I went Sofa's route and cut the guides to .530, went with a positive style Viton seal and then to Comp 26918 springs and .050" offset keepers to get the springs close to the 1.8" spec height (using the stock valves).

sandman92084

I read tons of posts that said these springs should fit fine and to get the correct closed spring seat pressure with the ls6 spring and lt4 hot cam you need to set install height at 1.750" but this guy said they were so tight against the guide boss some wouldn't even go down to the seat thats why he decided to use the cutting tool. Anyway I'm home now looking at everything and as much as I hate to admit it, i read the mic wrong. The retainer is small enough it sits on the lower ledge below the top of the mic which is .150" higher so that actually makes my install height around 1.730. So now my question changes. If i touch up the spring seats with the cutter to get right at 1.750 do i even need to use a spring locator with the iron heads?

sofakingdom

iTrader: (1)

Not really. Not, that is, if they fit reasonably tight in the pocket.

What cam are you planning on using? What's the clearance, retainer to guide (seal)? Might not even be necessary to do any more cutting.

The cam choice doesn't matter to choosing spring pressures and setup generally, beyond making sure that you have "enough" but not "too much". Which of course depends on what type of cam it is, more than which specific one.

sandman92084

I don't have valve seals in yet but the clearance from the top of the guides to the retainers is .750-.760 so should be plenty of room there. I'm using the lt4 hot cam with 1.5 rockers. I had thought about changing to 1.6's later but haven't made any final decision on it.

sofakingdom

iTrader: (1)

Seals for .630" guides are pretty thick...

Don't "should be" ANYTHING about building an engine. Measure, measure, measure. Don't buy parts that "should" work until you have the ones they depend on, in your hand to measure.

sandman92084

The guide boss was cut to .630 but it will still use the factory seals. I have felpro #SS72861. I do plan to check clearance when seals are in I'm just thinking even if they sit a full 1/4" above the top of the guide that still leaves clearance for the .495" lift. Thanks to everybody for all the quick input by the way.

sofakingdom

iTrader: (1)

Put the seals in and MEASURE the clearance. "Just thinking" somehow is something that the parts just aren't aware of in any way. Won't change their size. Measure measure measure. No "assume", no "think", no "should be", no "I always heard", NONE of that. Measure.

skinny z

From the application it doesn't appear that you'll have any issues but...
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