Losh's Series I SS Ute (AKA Black Thunder).

[Deuce]

As far as springs are concerned, cam degrees don't matter. Lift matters.
You will select springs based on three things.
1) size - this is determined by your head. Not much you will be doing here.
2) valve lift - a dial gauge on top of a pushrod or lifter bucket etc, just to see how much it moves. Spring needs 50thou more travel at installed height than what the valve moves (so don't forget to multiply the cam lift by the rocker ratio)
3) rpm - your Dyno chart shows max rpm set in the tune. Just stick with that and you should be good.

 

[Skylarking]

The factory lobe isn't the same height as the cam journal so aftermarket cam grinders can profile larger lobes before they need to start grinding into the base circle.

That’s what I thought initially and that was my experience with the 4 cylinder motors I’ve played with.

Interestingly I was reading about the differences in LS engines and it seems the cam journal diameter varied and there were two journal widths. Through the years the changes were based on model and year but also on feature set. Seems the higher power engines and/or ones with AFM/VVT had wider journals so as to carry more load while oil pumps provided higher oil flow and pressure, amount other differences…

But I found nothing to quantify or even discuss the headroom between the cam lobe top and the journal diameter. I’d suspect you'd want some headroom/clearance to make cam install less risky as nicking bearings would be highly probable when they are pushed into the block if there was no headroom

Whatever the case with lift, etc that may influence valve springs, @losh should find out soon enough what the underlying failure is and then he can move forward from there. If it was me, I’d want to talk to the original engine builder re the parts used and whether the6 were an owner induced cost compromise. Guess every engine builder has his own ideas as to what is best though owner budget may have an influence on parts choice…

 

[losh1971]

I believe the tech has arrived. I haven't heard anything yet so will just have to wait. The waiting is the hardest part lol, as it's the not knowing what he will find. On another note my Pioneer HU arrived today. So once I get my install kit I will have all I need to get it fitted.

 

[lmoengnr]

As immortality stated, LS standard rocker ratio is 1.7:1, the dimension of the rocker pivot to the pushrod socket, and rocker pivot to the valve contact point. To change the ratio, you need to change the rocker dimensions.

 

[losh1971]

Broken valve spring

 

[Skylarking]

Broken valve spring

That's good to hear as it's a much cheaper fix that you can do yourself (if you want) as compared to some engine out rebuild to fix a hole in a piston

Now the question becomes whether a single spring failure was a one off, early in the life of the new spring presumably installed when cam put in, or something that would require you to replace all springs? Can't offer advice on that front though i'd thing many would say just replace all springs.

 

[losh1971]

 

[losh1971]

I took the advice of the technician and I'm going to just replace the one spring. He agreed that if it happens again we replace the whole set, which is a fairly expensive exercise.

 

[Immortality]

Probably the best failure you could have had and got away with no major damage.

Now to work out what springs are in it.

 

[chrisp]

Broken valve spring

Well done not driving it after you noticed the issue.

It’s a great example of not ignoring a problem and getting the problem attended to early. You have saved potentially extensive and expensive damage.