1G Valve spring Shimming

[bryanzomg]

I’ll cut to the chase. Confirmed valve float, limiting my boost and RPM usage.
I guess machine shop screwed up when they cut my valve seats and replaced the valves and installed my springs.
I’m running kiggly steel streets with FP3 cams.
How likely am I going to run into an issue if I shim my valve springs 0.060” (kiggly recommended for ~104lbs) WITHOUT measuring spring tip height

 

[donniekak]

You need to measure your spring installed height.

 

[1990TSIAWDTALON]

And watch for coil bind.

 

[bryanzomg]

Aw man, I guess I’ll be pulling the head

 

[ist dwa]

I am not familiar with valve floating a DSM head, I have never done it, What exactly does it take do so? I have run over 30psi on completely stock valve train to 8,200. I've done 40psi at 8500-9 on EVO beehives without problems also.

 

[bryanzomg]

I am not familiar with valve floating a DSM head, I have never done it, What exactly does it take do so? I have run over 30psi on completely stock valve train to 8,200. I've done 40psi at 8500-9 on EVO beehives without problems also.

I’ve got fp3 with cut valve seats. It’s fine at 25psi till 8,000 rpm. If I run more boost it’ll drop down “limiter” and hit almost like a backfire and it’ll seemingly “drop” a cylinder “misfire” for a few seconds and eventually clear up. I’ve exhausted all other possibilities.

 

[donniekak]

And watch for coil bind.

It’s hard to measure installed height in these heads.
Sometimes your best bet is a feeler gauge and the the paperwork for the spring. However I wouldn’t recommend that method for someone unfamiliar with working on heads. To easy for them to eat a valve with a measurement error.

I’ve got fp3 with cut valve seats. It’s fine at 25psi till 8,000 rpm. If I run more boost it’ll drop down “limiter” and hit almost like a backfire and it’ll seemingly “drop” a cylinder “misfire” for a few seconds and eventually clear up. I’ve exhausted all other possibilities.

That does sound like float. The car will sputter and run like a Subaru until the lifters bleed back down.

 

[bryanzomg]

It’s hard to measure installed height in these heads.
Sometimes your best bet is a feeler gauge and the the paperwork for the spring. However I wouldn’t recommend that method for someone unfamiliar with working on heads. To easy for them to eat a valve with a measurement error.

I’m gonna take it to someone who’s got a lot of DSM experience locally

That does sound like float. The car will sputter and run like a Subaru until the lifters bleed back down.

That’s exactly it! I’ve exhausted everything, even logged fuel pressure and the ultimate conclusion is just that.

 

[jdxnc]

I talked to Kiggly directly regarding shimming, this is the answer I got:

As for shimming the steel streets to high pressure levels... Kevin said, 0.030” puts the seat pressure just under the HP pressure, and 0.045” puts it just over the HP pressure.

 

[bryanzomg]

I also talked to Kiggly in regards to my situation with fp3 cams and kiggly streets and Eric said
“
What rpm are you running to? The FP2, FP3, FP2x, and FP3x were cheater cam profiles from a valve acceleration point of view that really need a ton of spring to go to high rpm. I have relatively detailed profile data on the FP3's. At 85lbs of seat force, that matches up to only an 8200rpm float point. Intake runs out of dynamic spring force (floats) about 300rpm before the exhaust on this grind. If you shim up to ~104lbs (0.060"), this should be good for about 8600rpm.

Seat pressure for popping valves open still uses the standard rule of 1.7x manifold absolute pressure. So, for 30psi, you have 45psi absolute manifold pressure. This should only need about 77lbs on the seat.”

 

[danl]

That does sound like float. The car will sputter and run like a Subaru until the lifters bleed back down.

Needed to say this is the best description of valve float on a 4g63 I’ve ever heard of.

Also wanted to mention to the original poster that you need to inspect your cams, rockers, and valve stems for damage. I had valve float on a 4g63 years ago that damaged the cams and rockers in only a couple hundred miles.

 

[bryanzomg]

Needed to say this is the best description of valve float on a 4g63 I’ve ever heard of.

Also wanted to mention to the original poster that you need to inspect your cams, rockers, and valve stems for damage. I had valve float on a 4g63 years ago that damaged the cams and rockers in only a couple hundred miles.

Did valve cover the other day, everything looks pretty solid to me

 

[ist dwa]

I am just going to say this politely as a huge FP supporter, the FP cams are complete junk (there is a reason they don't sell them anymore), they were notorious for throwing rockers etc. Get some Kelfords or GSCS3 and see if that fixes the problem.

 

[bryanzomg]

Can anyone post what the specs should be for a variety of “things” in the head? I’m gonna pull head and send out to a machine shop but I want to give them specs to make sure everything is in order to avoid issues and make sure geometry is okay

 

[bryanzomg]

So far I have is spring tip height. Intake spec is 1.937" and exhaust is 1.910", be within 0.010

 

[bryanzomg]

Just an update, ended up pulling the head and sending it to Opel automotive engineering machine shop. Turns out valve and valve spring geometry was way off & there 8 missing 8 valve seat springs (previous machine shop did that we they damaged the area installing valve guides)
Ultimately ended up with new GSC valves,super tech seals and shimmed for 102lbs. I’ll be retorquing head studs tonight & installing Kiggly HLA and I’m gonna let her eat

 

[bryanzomg]

Final update can be set as RESOLVED. She pulls beautifully to 8100 at 31psi with no hiccups! It’s been a journey thanks all!