how critical is installed valve spring height?

[copper67sat]

I bought a new pair of 440 Source Stealth aluminum heads for my 383 build - 9.5:1 street build with HUG SEH1620BL-12 flat tappet hydraulic cam (specs below). Based on things I have read in this forum and elsewhere, I sent the heads to the machine shop to be checked and they reported that some of the seats were not installed correctly. Supposedly they corrected the seats and blended the chambers, performed a valve job then set the valve stem heights and spring heights to "Competition Specs", whatever that means. 440 Source specs their springs at 1.875" installed height - I wish that I had checked these before they went to the machine shop. I bought the Hughes springs (HUG 1106H) that are recommended for the cam which call for 1.880" installed height. That seemed close enough to the 440 Source spec that I didn't think I'd have to make any adjustments but thought I'd check anyway.

I measured anywhere from 1.825" to 1.844" using a Proform valve spring height micrometer. I verified the measurements more than once, especially for the min and max outliers, and the differences are far larger than my measurement error. First, the variation from valve to valve bothers me, but perhaps more importantly won't the shorter than spec installed heights lead to higher spring loads?

I started down the path of using +0.100 retainers from Hughes along with the appropriate shims to bring the spring heights into spec. However, the machine shop installed metal clad viton valve stem seals which do not appear to be easy to remove and reinstall and the shims won't fit over them. Am I overthinking this or should I try to get the machine shop correct them?

If I can't get the machine shop to step up or do the work on a timely basis, can the valve seals be removed and reused? If so, how? Also, are there any issues with using multiple shims? The shims come in .015, .020, .030 and .050. I mapped out the combinations of shims needed bring each valve into spec and some valves need as many as 3.

Thanks in advance for any guidance from the experts.

 

[PRHeads]

Did the heads get reassembled with different retainers/locks than they were delivered with?
The reason I ask is, the IH on them is usually pretty close to 1.875, and should actually have increased slightly after the seat work.

Have you verified the height mic is correct?
Just set it to 1.875 and measure it with a caliper.

If the IH is actually as short as you say, there’s likely shims under the spring cups.

Carefully prying the seals from two sides will usually get them off.
Take the little springs off before working the seal up over the keeper groove.

If you’re going to use that Hughes spring I def wouldn’t be running the IH any shorter than 1.88”, and if 1.90” was available that’s what I’d shoot for.

 

[copper67sat]

Did the heads get reassembled with different retainers/locks than they were delivered with?
The reason I ask is, the IH on them is usually pretty close to 1.875, and should actually have increased slightly after the seat work.

Have you verified the height mic is correct?
Just set it to 1.875 and measure it with a caliper.

If the IH is actually as short as you say, there’s likely shims under the spring cups.

Carefully prying the seals from two sides will usually get them off.
Take the little springs off before working the seal up over the keeper groove.

If you’re going to use that Hughes spring I def wouldn’t be running the IH any shorter than 1.88”, and if 1.90” was available that’s what I’d shoot for.

Thanks for the advice. I did not provide the shop any different retainers or locks so presumably they were reassembled using the same ones delivered by 440 Source - they certainly look what came on them. I wish I had taken baseline measurements before any work was performed so I'd know how things changed after the machine work. As you stated, I also expected the heights to increase after the machine work which makes me wonder if they were way out to start with. I am also finding that the chamber volumes vary from 82.2 to 83.6 cc which is more than I expected and larger than 440 Source states (80 cc) but I'm not sure that will make much difference in the big scheme.

I will definitely check the micrometer. It is brand new but who knows what quality control they have.

 

[PRHeads]

I’ve checked several stealths for chamber volume…….and 82-83 is what I often see after cutting the seats.

If there are no shims under the cups, and the mic is correct, that’s pretty far from spec imo, and I’d address it……somehow.

 

[PRHeads]

Looking at the posted specs, the Hughes springs have a rate of 336lbs/in.
If they’re 150lbs at 1.880, that would put them at 166lbs at 1.830.
Imo, that’s asking for a problem.

 

[copper67sat]

Yeah, I calculated the same change in spring pressure which worried me since Hughes likes stiffer springs. I bought the cam, lifter, spring, oil package from them for their "No flat cam guarantee" and am following their instructions, all 13 pages.

I removed the seal and the cup was shimmed. Removed the shim and remeasured - 1.875". Also checked the mic and it's good within my measuring capabilities +/- .001

Based on this and measuring the shim, I think my original measurements are also off at least .005. I don’t think I had the gauge tight enough to put sufficient seat pressure on the valve.

I need to measure the rest of them but the guidance here is to have no less than 1.88-1.9. The only solution I have found so far, short of more machine work which I'd like to avoid, is to go with +.100 retainers and locks then shim back down.

 

[lewtot184]

Not checking all valve train components and their movements can be a disaster waiting to happen.

 

[69Bee]

Sounds like the machine shop conned you to get money and doesn't know what they are doing anyway (Competition Specs, pffft). I would remove the shims under the spring cups as you have already found out that it should result in the proper 1.875" IH. The heights don't have to be identical, but within 0.005" would be good. The seals will rip on the inside and will not work if re-installed; get new ones from Comp Cams, ebay, internet. Measure the guide OD and it will be either 0.532" or 0.562", then get the proper seal to fit the valve stem which is likely 0.341" dia. The reason the height mic read low was because you can't get a proper reading with a seal on the guide. The seal will hit inside the mic barrel and prevent it from fully touching the spring cup. I would disagree that that valve seats were installed incorrectly, but rather the seat was improperly cut! I see this a lot on imported heads and all you have to do is cut a proper seat and just touch up the valve so that everything matches. I think it was a new 4.0 jeep head I purchased where the intake seats were so screwed up, ball point pen width and did not match the valves at all.

 

[rickseeman]

Hughes knows more about cams than me but WOW, 150 on the seat. That's more than a Race Hemi. It sounds like 440 Source had them closer than your machine shop. I've removed those valve seals with Channellocks and I didn't think I hurt them but now I have a Goodson tool for that.

 

[copper67sat]

I have disassembled 1 head and they were all shimmed the same. One curiosity, the intake shims are stamped 3135 while the exhaust shims have no markings but they are all the same thickness. Are they different?

I did notice that the seals were tearing on the inside and leaving pieces on the guides so figured I'd need new ones. Thanks for confirming.

Agree that the shop ripped me of on at least some of their $250 head assembly. They didn't ask me what spring height I needed and set it to something that would have caused me problems so I am glad I checked.

Thanks for all the input.

 

[PRHeads]

While I’d prefer 1.880-1.900, I wouldn’t jump thru hoops to get it.
If you have at least 1.870 with the shim removed you should be okay.

 

[rickseeman]

Dwayne: Don't you think 150 on the seat sounds high? I mean, I think of a hydraulic roller taking a lot more spring and the Trick Flow .600" lift hyd roller only asks for 154 on the seat. I would have thought his cam would ask for more like a stock Street Hemi spring? Am I crazy?

 

[copper67sat]

I have finished tearing down and measuring both heads. All were shimmed with the same thickness shim so they did nothing to try to equalize them. Not what I was expecting, even if they're the wrong height, because the line item on the invoice states that they would equalize them.

I am still finding a few spring heights in the 1.60s with no shims and almost all are on the low side from 1.875 so it looks like I'll have to use the +.100 retainers and then shim back. I can get an average of 1.886 +/- .004. Any concerns with using multiple shims to achieve the desired height?

 

[Kern Dog]

I don't understand how you found spring heights shorter than the target number while not being shimmed to get there.