eman930

Hey guys, Quick question, my head is at the machine shop getting rebuilt, I'm being told that I need new valve springs because the old ones are weak at 105lbs, I've done valve seals and have the tool to remove the springs, Can I replace the valve springs myself or would the machine shop need them to finish doing a rebuild? I'm just trying to save myself some $$ as I'm being told its $230 to have them do it, and I can get the springs for $146 and do it myself.

Van

Ideally you want to measure the force at the "installed height" of the springs, and put shims under them as necessary.

But, chances are, if you just put the springs in, you'll be fine.

refresh951

105 to 110lbs is about what I have measured on most used OEM springs. On a stockish motor they are probably fine. I think the springs run fairly close to coil bind and loose some strength early and then level out at about 105-110lbs. Was 105 the minimum? At what installed height? I would be interested in others comments on this.

eman930

Id be intrested as well, book says 130lbs, I never noticed any running issues with the car even with boost turned up.

Van

It would be an RPM issue, not a boost level issue.

eman930

How are the pelican parts valve springs?

blown 944

If you've done the springs before you can do them again. You should be fine though unless you're planning on crazy mods.

Dave W.

I got a set of springs from Pelican. 7 were good, one was oddly shorter, but it was still better than original 110k mile old stock springs.

H.F.B.

Instead of new springs, another option could be lightweight SS Si-Valves. Especially the exhaust valves. As we know over-revving hurts the mainly the exhaust valves.
The 951 exhaust Si-Valves are significantly lighter (just 94 gramms) than the stock exh. valves and cheaper than new springs.



left: my race prepped stainless steel exhaust Si-Valve, right: non race prepped exh. Si-Valve, 94 gramm (3.3158oz)

Smudo

Do you mean these ones? http://fcrcmachine.com/i-19290330-ne...l-e-t3087.html

Can you get them also in other place (seem to be not available) and what are the quality of those valves?

H.F.B.

yes, these are the valves in my cylinder head. I ordered them directly from http://www.sivalves.com/.
No problems so far.

fejjj

I beleive Shawn is using the SI valves as well as he was the person who told me about them.

refresh951

I have built a few heads using SI Intake Valves. No issues so far. They are a bit on the heavy side but quality is good and the price is excellent. I like to use stock exhaust valves however because they are sodium filled.

Smudo

H.F.B. above said that they are significantly lighter than stock. Do you compare them to some other performance aftermarket valves?

What are the advantages of the sodium fill? Better heat resistance/transfer?

refresh951

Intakes are slightly heavier than stock. Not sure about exhaust.

Heat transfer. Keeping the exhaust valve cool is very important on a turbo car, especially if you track the car.