All Small Six Valve spring replacement

[td9323]

Hey all. I'm having an E0 large log head milled for my stock 1966 200 shortblock. I have a set of Comp 903 springs here. Will they be ok for use with the stock cam?

 

[clochard68]

pmuller9 suggested the Comp 903 for my 68 small log 200 with stock cam and I followed his advice.
Haven't run the setup yet but I will stick with the 903, if that is of any help...

 

[TrickSix]

Specs I saw for those springs, 80 lbs @ 1.70" and 212 lbs @ 1.25", are stiffer than the 302 valve springs people often use as a step up from stock. What is the need for so much pressure with a stock cam?

 

[td9323]

I don't really think I need them but I already have them and the head is apart right now. Just thought I would use them instead of the 134k mile stock ones.

 

[clochard68]

I have 1.65 ratio rocker arms, that's why I opted for a stiffer spring. Maybe your setup doesn't require it. In this regard we need someone with more experience with valve spring pressures, all my knowledge only comes from the falcon performance handbook...

 

[TrickSix]

My original head is stock other than some minor mods to improve oiling and a little milling to make up for thicker modern gaskets. I've got a C4 so I'm never gonna see high rpms, and I'm going to stay with a stock cam. But I'm using some 221 retainers in a big log/big valve head I'm almost done with. They're thinner as well as lighter, so the installed height is higher, meaning a step in the wrong direction for the stock spring's pressure. I didn't want to jump way up to more spring than I needed, the 302 springs seemed like overkill, and finally settled on some 240 police/taxi exhaust valve springs all around. I found it very helpful when comparing springs to plot them all on a graph so that I could compare apples to apples. One axis of the graph is spring pressure, and the other is spring height. Spring ratings usually have pressures given at two heights, but not always at your open and closed dimensions. Just plot the two points on your graph. It's pretty much a linear function, so then draw a line through those two points. Now you can see where that line intersects your height lines, and read what the pressure is there. I wish I could post pics easier, I'd show an example. But it's pretty simple, and gives a very clear picture of how different valve springs compare.

 

[TrickSix]

I don't really think I need them but I already have them and the head is apart right now. Just thought I would use them instead of the 134k mile stock ones.

I see many reports of new cam and lifter failures on various forums these days. I wouldn't want any more spring pressure than what was needed. Yes, your old springs are pretty well used up. But possible premature wear on your camshaft seems a high price to pay for the money saved from using springs you had laying around.

 

[pmuller9]

I have 1.65 ratio rocker arms, that's why I opted for a stiffer spring. Maybe your setup doesn't require it. In this regard we need someone with more experience with valve spring pressures, all my knowledge only comes from the falcon performance handbook...

The comp 903 springs solved the coil bind issue you had because of the 1.65 ratio rocker arms.