Can You Shim Valve Springs Too Much ? - Team Camaro Tech
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post #1 of 14 (permalink) Old May 16th, 04, 11:24 AM Thread Starter
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I started to assemble my vortec heads today with Comp 981 springs, 10 degree retainers, and + .05" installed height locks. I also have a shim kit that has .06", .03", and .015 shims. I had to use one of each to get pretty close to my required installed height of 1.70" (It was around 1.72"). I checked this by holding up on the retainer with the locks installed.

I installed the spring, and it pulled the locks deeper into the retainer, increasing my installed height. I could go with standard locks which would put it very close, but then I'd have to give up the extra retainer to guide clearance that I wanted. The 10 degree retainers have a deeper center section than the stock ones, and I'm afraid I'll be running too close.

I think if I get another set of .06" shims and swap one of them for one of the .015" ones, I'll be OK. That will give me .15" in shim height using three shims under each spring; does that sound OK ? Sorry if this is a dumb question; this is new territory for me. Thanks, Ron.
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post #2 of 14 (permalink) Old May 16th, 04, 12:15 PM
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That sounds way, way off. Every vortec head I have used has had a 1.70-1.75 installed height right out of the box. Are you using a height mike or a machinist rule, or what? What retainers are you using? In case you wasn't aware, the retainers have to match the locks...7* locks must be used with 7* retainers. Normally you would use a +.050 lock (I am assuming comp 10* +.050 locks since they don't make a 7* +.050 lock) along with a .045 or .060 shim...this would keep your installed height the same and give you +.050 retainer to guide clearance.

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post #3 of 14 (permalink) Old May 16th, 04, 12:37 PM
 
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I have 7 degree locks on my Merlin heads. I think they are made by VTO, got them from Competition Products.

I think one way to skin that old cat I used to talk a lot about is to grind stock retainers some to gain the needed clearance IF it isn't that extreme!!!

Might consider it..

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post #4 of 14 (permalink) Old May 16th, 04, 01:28 PM Thread Starter
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Thanks for the quick replies ! Yes, I do have the 10 degree retainers to go with the +.05" locks. I went back and looked at things again.

I checked this on an intake and an exhaust valve: I put the stock 7 degree retainer and keeper back on the valve and measured with a steel machinist rule (marked in 32nds). The installed height was dead on 1.70", just like it was when I disassembled it.

I put the 10 degree retainer and lock on the valve next to it (I pulled hard on the retainer to seat the locks this time). The bottom of the retainer on the 10 degree one is about .06" higher than the bottom of the 7 degree one, but the surface of the retainer where the top of the spring sits is about .15" higher on the 10 degree retainer than the 7 degree one. I swapped valves, rechecked, and got the same results.

The reason for the difference is the different design of the retainers. With that said, am I OK to shim my springs that much ? I don't really see that I have any other choice. Thanks, Ron.
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post #5 of 14 (permalink) Old May 16th, 04, 05:50 PM
 
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Why do you think you need the extra Heavy-Duty 10 degree retainers and keepers??

I ask b/c Chevy never ran 10 degree stuff on any of the motors and seemed to have gotten along just fine.

If you are running a "balls-out" solid roller, yes, but not for anything that remotely can be considered streetable, imho..

AND a second design -140, Z cam is imho, about borderline for a street cam.

I ask b/c why go through the hassle if it's not needed in the first place...

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post #6 of 14 (permalink) Old May 16th, 04, 06:33 PM
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Wow...I wouldn't have thought there was that much difference between the 2. In any case, it sounds like 2 .060's and 1 .030 will get you where you need to be.
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post #7 of 14 (permalink) Old May 17th, 04, 01:53 AM Thread Starter
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I know that the 10 degree retainers and locks were a bit overkill for the cam that I'm running, but they didn't cost anymore than the Comp 7 degree pieces, and they're supposed to be better, so I figured why not ? They sure do look a lot stronger than the stock 7 degree ones; that probably translates into more weight too, I guess.

I guess I'll get another shim pack and (finally) get these things put back together ! Thanks again travis and pdq67 for your help !
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post #8 of 14 (permalink) Old May 19th, 04, 03:31 PM Thread Starter
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Well, I got my extra set of .06" shims and started putting these vortecs together. I get about three valves assembled, and I notice how close the top of the valve stem is to the top of the retainer; for some reason the tips of the intake valves are about .03" shorter than the exhaust valves too.

I started getting a bad feeling about my self aligning rockers. I got one and tried it; it barely touches the valve tip on the exhaust valve, and doesn't touch the intake valve tip at all ! I'm not going to be able to use the +.05" valve locks, and I don't need the shims that I just bought.

I don't think that I'd be any better off with roller tip rockers either, since they'd have to be self aligning. Now I'm going to have to get some standard 10 degree locks. This will give me a little over .06" of retainer to guide clearance at .480" lift; I hope this is enough.

This is getting to be not fun anymore !
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post #9 of 14 (permalink) Old Jun 27th, 06, 07:11 AM
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Re: Can You Shim Valve Springs Too Much ?

sounds like it's time to get the heads machined for screw in studs and guideplates. probably need the flat guideplates, but you'll also want to have the pushrod passages thru the heads drilled out to 1/2" also.
about $125 around here, but the heads have to come off.
Eric B

86 camaro,383,topline vortecs,scat crank,wiseco forged 9.5:1,6"scat rods,comp xs282s,performer rpm,750 proform vac sec,msd in cap, hooker coated 1 5/8"headers,3"flowmaster,700r4,2800 stall,3.42 10 bolt posi,hotchkiss lca's,aje tube k member & a-arms
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post #10 of 14 (permalink) Old Jun 27th, 06, 08:19 AM
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Re: Can You Shim Valve Springs Too Much ?

Too many bugs in this issue. When you talk about spring height etc. Like someone mentioned, its pretty much generic to set spring height and go unless you have other issues? Like some valves sunk too far into seat? Its ok to use the special lock but not so critical with stock range cams and springs.
Another issue is all these shims. Too many will cause the spring to slip around the base unless you have some type of retention well? Spring seat cups will help you get out of this if needed.
Also don't forget the rocker arm geometery, you may need some longer push rods to help with that... There is a cheapo tool to help.

Don
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post #11 of 14 (permalink) Old Jun 27th, 06, 05:35 PM
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Re: Can You Shim Valve Springs Too Much ?

Ron,
Why are you using the +.050 locks ??????? If you get rid of them and go with a normal 10 deg lock, you will be able to get rid of at least a .060" shim.

Also,

You said that when you checked the installed hgt, it was 1.720" .... well that would only require 1 shim to get it pretty close.

You really need to check the hgt with a hgt micrometer so you can put some pressure on everything. Generally, when you tighten up the hgt mike, you pick up at least another .030", smack the top of the valve a couple of times to seat the locks in the retainer and you get even more.

I think you need to get someone to show you the proper way to measure this so you can get it correct. It is pretty important.

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post #12 of 14 (permalink) Old Jun 27th, 06, 05:47 PM
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Re: Can You Shim Valve Springs Too Much ?

I'd be willing to bet Ron got this figured out a LONG time ago...this thread is over 2 years old

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post #13 of 14 (permalink) Old Jun 27th, 06, 06:46 PM
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Re: Can You Shim Valve Springs Too Much ?

Doh !!!!!!

Bill Koustenis
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post #14 of 14 (permalink) Old Jun 30th, 06, 04:55 AM Thread Starter
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Re: Can You Shim Valve Springs Too Much ?

Wow ! I was suprised to see this thread come back ! Believe it or not, I haven't started this engine yet ! While I was into the engine, some friends and I were also performing major sheetmetal surgery and painting my car.

I set the engine in before we put the painted fenders back on, and I'm still trying to get this thing back together !

I did use the normal 10 degree locks; so I didn't need that extra .060" shim. The reason that I wanted to use the +.050" locks is because I felt better with the extra retainer to guide clearance. The reason that I needed all of the shims in the first place was because the surface of the retainer where the top of the spring sits is higher on the 10 degree retainer than the 7 degree one. I was not able to find spring seat cups in the diameter that I needed.

My hyd roller cam only has .474 advertised lift, so I don't feel that I need screw in studs; I'm not sure how that rocker arm geometry is an issue either, since I didn't change from the 1.50 rockers.

I'd be lying if I said that I'm not going to be a little nervous until this thing runs a while, but I have no plans of taking these heads back off. I'll let you guys know what happens (or doesn't happen, hopefully !) when the time comes. Thanks, Ron.
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