valve spring shim installation theory

40cpe

40cpe

Well-known member
I'm installing Red's Zephyr valve springs on Manley Pro Flo (longer) Chevy valves and Red's guides. A .060" shim gets most of them to an installed pressure of ~52#. I have a couple that have installed height about .025" longer and am thinking of adding a .030 shim and use some of the softer springs on them. The problem is that the register on the guides are only about .080" tall and although the shims will register, the springs will be on the necked-down part of the guide, which measures about .625 instead of the .688 on the register. I've read several times not to put the shims on the retainer end of the spring, but no one has explained why that is detrimental to the operation. I've also seen where someone has machined a sleeve to increase the register on the guide, but that is not an option for me. I'm hesitant to install both shims at the guide end and have the spring on the smaller diameter of the guide for fear of the spring walking around on the shim, creating wear and metal particles in the oil.

The other option is to use some of the stronger springs on these valves with only the .060" shim. My testing indicates there is 5-6 # increase with for each .030" of shim added. so with the stronger springs I would have maybe 48# on these longer seat length springs. Am I straining at a gnat? I welcome opinions on how to proceed from ye experienced in this area.

The thumbnail picture is upside down but is turns right-side up when I click on it in the preview. Hopefully it works for you.

With so much measuring of springs I devised my own device to use with the bathroom scales. I'll save that for another post.

edit: picture doesn't correct itself in the post. sorry.
 

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Those longer valves cause more headaches than they're worth? You don't have enough spring-register height on the guides to use compound shims.

If you stay with the "standard" length FH valves the spring pressure dilemma can be avoided. When we want to put the lifter adjusting nut "down" further than normal, or for a small-base cam, we simply use lash caps.

Thanks, Gary in N.Y.

P.S. Crane also has the 7* shorter-installed-height locks, usually -.050". They also have the taller ones, +.050".
 
The reason for not putting shims on the retainer end is weight added to the sprung end, this extra weight to be controlled by the spring upsets all the careful measuring and calculating a desired spring pressure.
If the shim is at the guide end, no weight added.
Martin.
 
I agree with Gary re the standard lengthy flathead valves and installed hight. The different hight locks are a good idea.
How tight are you gonna turn this engine? What kinda profile on the cam?
The odd ones, what is the pressure with one shim?
A slow lift rate cam and genuine street driven keeping the rpm below 4500-5000 ain't gonna be as needy on exact spring pressures as a high lift rate cam and 6500-7000 rpm.
Martin.
 
Martin, thanks for the reason for no shims on the retainer. I wonder if it would matter in a street engine. This is a 276/L100 with no breathing mods except for the pro flo valves. I'm starting with one 94 carb and MAYBE go to two or a small bore chevy carb after everything settles in. I don't intend to race it so I don't expect to see 4500 rpm. The seat pressure on the taller installed height is about 47#. Maybe I just need to put the strongest springs on the longer seat height and let it go?

Goesfast, The longer valves do keep the adjustment screw low. I'm seeing about 2-3 threads out of the lifter. I would need shims for standard valves/springs and maybe too much pressure with Zephyr springs. Us casual builders don't have an assortment of different parts to mix and match to find the best combination, and probably not the knowledge to use them effectively if we did. I try to glean info from this forum and order the parts I hope will work. I loose 3days every time I re-order.

Ronnie, The down locks would have been better in retrospect, or maybe the .035 with the right shims. Maybe next time. Thanks.

So with me where I'm at, is about 5# variance in pressures reasonable in a street engine?

Thanks again to all.
 
Back in the old days when we were just as short of money as brains. We never thought of the technical aspect of the valve train and hi 80-80 lbs of spring pressure was the norn. Not having the funs to buy heavy duty springs we'd just make uo spacers, usualy out of alum tubing. The funny part of it is: It worked, coarse we ruined a few lifters and ware out a few cams, Now I use the chevy valves ub-nder cut, because they don't have the right shape for a flathead. I also use the cheep OEM valves because the;re made of netter material than the SS aftermarket valves, Nw however I can afford a set of LZ or Isky 185 springs. I run all my STREET cams at 50/55lbs. and yes I like lash caps,
 
If I had to do it all over I would just grind the stems and use stock lifters. I used shims a lot of thin ones as I remember And I think on the top collar, I think it will work OK. Looking at the top collar .040 thousands didn't seem to reduce the area under the pad too much. L100 cam 55-60 lbs. seat pressure with chey valves, I guess I won't know for a while yet?
 
We use Chevy valves at our shop, and install hardened seats to match. New valve springs all around are used, as most old springs have taken a "set" from being compressed over a long period of time. Why risk a rebuild to save $2.50 each on springs?
 
I installed an Isky cam in my 53 with 50 lbs spring pressure. The engine runs rough at 3000rpm and above. I discovered Isky recommends 85 lbs for this cam and suspect it could be the problem. Any thoughts?
 
Sounds like a 400 jr, theu need allot of pressure. The last engine I built was Robs 294 with an L-100. 50/5 on all valves. now this is a street engine but every once in a while you have to blow the cob webs out of it, and wind her up. seen over 5K several times. As for putting a .035 on the retainer, I don't see a problem, you ain't builden a Swish watch.
The engine was designed in the late 20's with no computers and it ran just fine
 
Just a tip to add here, but if you are at 50# and use different style locks you can pick that up to 65# with no add'l shims. We do this all the time, not only on the Flatheads.

I hate to disagree with some here, but adding any weight to the topside of the valve ***'y (shim at the retainer end) is just not "right" over here. You actually make the spring work more due to the add'l weight topside! It's for this very reason that on a progressive-wound spring it's recommended the "tighter" coils would be on the spring "seat" side and NOT up at the retainer end! Simple "physics" so to speak.

(Add) This post was to answer Bob above, I should have used the "quote" button!

The Isky 185's aren't a "progressive" spring, at least on the sets I have here on the shelf!

Thanks, Gary in N.Y.

P.S. A .035" shim will yield an add'l 10# where the locks add 15#. I AM assuming you have "std" length locks in the unit??
 
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As a practical matter the addition of a gram of .030 spring shim on the retainer end will be completely meaningless in a street engine.
 
JWL said:
As a practical matter the addition of a gram of .030 spring shim on the retainer end will be completely meaningless in a street engine.
Click to expand...

John is correct. Those longer valves are already a few grams heavier than a stock Ford valve. The few tenths of a gram that the shim weighs is nothing.
Who actually weighs their valves? Nobody. There is no spec. out there on what it should weigh for a given spring pressure.
 
While I do agree with John's analysis about the "effect", the truth is the shims do not belong on top, period.

If close attention is paid to detail's there is really no reason to have even one single shim ANYWHERE in the program. Between the various springs, the fact we have the 7* locks available that run from -.050" to Std. to +.050" sort of makes the job very doable without shims! We can actually go to the length's of having the valve key locations changed. This would require "custom" valves of course, somewhat expensive! I would add, we haven't needed this option yet!

I really can't recall the last build where we used a spring-shim at all. I am not against using them, we just find most builds don't require them?

(Add) For Randy above, valve weight may not matter on the Flathead program but it's one of the most important numbers in the racing world. We have the intake and exhaust valve weights recorded on EVERY race build we encounter! I'm sure you know about "Titanium" retainers and their weight, well now you can even get them lightened with holes drilled through. It's just not applicable here!

Thanks, Gary in N.Y.

P.S. This posted issue is a major reason to do a complete mock-up beforehand on the build. It makes coming down the "home-stretch" much easier! I am in the process of trying to help a member here avoid this very issue on his own build presently. He's a distance away and I don't have the entire build "on the bench" here.
 
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