Valve Spring Height

[bbh03]

If the tolerance for valve springs is 34.35 +/- 0.15 mm, how can you be expected to make this with every valve if the shims are 0.5 mm? I assembled three heads today and three of the valves were set closest to spec at 34.6mm. The others were in spec. Are thinner shims available?

Also, how is this best measured? I measued the depth of the seat first, then measured the height of the sping from the top of the seat to the bottom of the retainer and added that to the first measurement...

[afterburn 549]

are you using the special tool ?? (fits over the valve)

[bbh03]

I wasn't aware there was one. Does Pelican sell it?

[ChrisBennet]

Perhaps if you signed your name and put your location in you profile someone nearby would be volunteer to loan you it. Hint, hint.
-Chris

[afterburn 549]

yea......and will make your life ez...got one here. and you know where I am at

[bbh03]

Alright, you guys talked me into the location thing, although 90% of you seem to be from the west coast! I usually sign my name, but forgot on this one.

Anyone have a link to this tool? I might not mind owning one myself if they don't cost too much! I don't think this will be even close to the last 911 motor I build!


Thanks,
Brian

[ChrisBennet]

Here it is on Pelican. http://www.pelicanparts.com/cgi-bin/ksearch/pel_search.cgi?please_wait=N&forumid=&threadid=&command=DWsearch&description=P228
The SIR tool # is P228 (SIR makes this tool) I don't recall what the Porsche # is.



I almost never use mine. The guy who does my heads sets the spring height for me.
-Chris

[911pcars]

The tool is just for convenience. After all, you're just measuring the distance from the retainer to the valve spring seat. You can use a vernier caliper to check installed height.

Go to the Smart Racing site and download the following doc:
MeasuringValveSpring_kit.pdf

Not sure about the OD of the valve spring, but there numerous sites that supply valve spring shims. Here's one

Sherwood

[bbh03]

I used the caliper method myself. If it is equally accurate, I would just continue with it.

With respect to the shims, my mechanic claims you can run upto 8000 rpm on stock springs if they are set right. Sound right?

[camgrinder]

With respect to the shims, my mechanic claims you can run upto 8000 rpm on stock springs if they are set right. Sound right?

It depends on what camshaft you have. Some factory cams are stable at high rpms with factory valve springs, but the SC or 964 profiles are not. The high lift profiles with short duration are " faster acting" cams than the old 906 style profile.

[stevepaa]

I cut a wooden dowel to correct height, one for intake and one for exhaust. Then I could use my fingers to place dowel like a height gage. Worked quite well. The SIR tool I bought was not marked correctly in its height notches.