Comp 918's Spring Height
 

The literature calls for 1.800 ins.
I had just this before a valve job.
After the machining, the installed height is closer to 1.900.
Is there a leeway for these springs?

OK, I'm starting to doubt the evidence, here. :engarde:
The original measurements were taken three years ago. I wrote them on a piece of paper, and all were verified between 1.800 and 1.810.
I can't imagine 0.100 having been removed from the back of the valves, and also from the seats.
The question is the same...can these springs work correctly @ 1.900?

Why not shim them?

Actually, why not shim them properly to within .050 of coil bind like you're supposed to?

I'm not understanding your comment, dr.
The installed height is 1.800. Spring bind is 1.200.
Even a .060 shim brings the adjusted height down to only 1.890.

Oh... Misread the original post. Apologies.

Hmmm. Seats are installed, retainers, and you're getting 1.9?

I've never heard of THAT much material coming off from a valve job. A .060 shim would put you at 1.84, but even that is much too loose for my liking.

What cam is in it? What's the lift?

Not a problem, Dave.
Everything is the same, (including the spring height checker), except for the machine work. Cam is TR224 561/114.
I took a caliper and opened it to .100, which is the difference between last year's 1.800 and the present reading of 1.9xx . The difference is too large to be believed.
"I'm confused" (my father used to say). :)

Did you use a different tool this time. I know some spring height mics don't properly seat with a beehive spring and will give a false tall reading.

My catalogue states the 26918 spring binds @ 1.100" which means you will
want 1.100" + .561" + .060" = 1.721" as your final installed height in order
to minimize high rpm spring surge.
I find it difficult to see just a valve job increasing the installed height by .100
unless an absolute "hack" had only an hour of time to bang it out. Was
anything else different like locks, retainers, or did you measure without
installing the valveseals which also has the .060" thick spring locator ledge??

Tool is the same.

All (the original) components were installed.
The machine work was completed by a trusted, reputable firm.
Add to this, that I thought that I had initially measured just an .45 increase (1.845) immediately after the work. Hence, my order for .060 shims.
After installing the shims, all readings showed 1.9xx.
The shim thickness was verified .060.
In the AM, I'll go through everything, again.

I was about to post that formula...

Good point on the seals. Also curious if the rest is the same, such as locks retainers and seats.

What heads are they, and who did the work? It may be time to talk to said porter, or bring them and let him measure just to prove it.

Dave, After shale targa posted the formula, I understood what you had posted, here.
"We've" just come in from the garage, where more readings confirmed the 1.96x height.
Seems impossible to have removed more than .150 of material. The perimeter of the valve end would be stripped right off.

Still seems odd man. I'm curious to see where this goes...

I wonder if the valve seat was accidentally cut deeper for a larger valve???

No offense, but it's more likely that you're doing something wrong than the machine shop taking .100" out of a valvejob.

Post pics of the process and tools you're using. As they say, a picture is worth a thousand words, and someone here with a sharp eye may be able to catch the issue.

If the valvejob really has been sunk .100", I'm not so sure the valvetrain will last. You would either need new seats installed or new heads.

No offense taken. I appreciate the assists.
Exhibit #1>> Previous spring heights were all between 1.798 & 1.810.
Exhibit #2>>New spring heights are all between 1.956 & 1.968!
The first thing I need to do, is to remove a head (there goes another gasket, and a set of head bolts), and bring it to the machinist to verify all, including having them measure a spring or two.

To refresh...all components are the same...everything, including the spring height checker. The only difference is the machining.
I knew exactly the condition of the heads before the work, and they didn't require any extreme work.
Let's suppose that the correct reading is 1.96x. How does one shim to an amount which will bring the height to 1.721 +/- (1.100 + .561 + .060) ?
Thanks to all..I'll keep you posted. ;)

Glenn

One other option would be springs that set up a little higher. Don't the LS9 springs set up at 1.900? Just looking at potential alternatives to re-machining heads, etc.

Thanks for chiming in.
If these springs work correctly at 1.9, I've got the .060 shims already.
They certainly would be cheaper than 16 valve seats + machining.
I was just reading a searched thread (in which you participated/2013) about shims...actually .188 shims were mentioned. I thought I was home free with the aforementioned shims, until I realized that the participants were speaking of ROCKER shims.
Can the same principle apply to spring shims?
...just trying to think this through before committing to something that is unproductive and expensive.

Have you considered talking to the guy that did the job? If he did them, and they're THAT off, I'd MAKE him replace the seats and redo the job.

You won't screw up a headgasket by just taking the head off if it hasn't been run yet.

I've found a resolution. After explaining everything, this site erased the entire post.
I'll re-post in the AM.