Maximum valve length
- Thread starter GGress
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PRH
Well-Known Member
Mike is probably the right person to answer that.
If you milled off the stands and did something like W2 stands you could probably use even longer valves than what the “normal” relocation spacers would accommodate.
If you milled off the stands and did something like W2 stands you could probably use even longer valves than what the “normal” relocation spacers would accommodate.
PRH
Well-Known Member
The valves that MP sold for W2 heads “back in the day” were 5.28(I)& 5.29(E) long.
PRH
Well-Known Member
I usually come at it from a different way……..
I figure out what spring I want to use, then see how long the valves need to be to accommodate that……… then decide if it’s worth the effort, or pick a cam that can use a shorter spring.
I figure out what spring I want to use, then see how long the valves need to be to accommodate that……… then decide if it’s worth the effort, or pick a cam that can use a shorter spring.
PRH
Well-Known Member
I’ve serviced some SS class heads for big blocks.
Those all had the stands milled off and were running Jesel rockers…….. and run cams in the .800” lift range with springs set up at a nominal 2.00” IH.
1.900”-ish IH on std SB heads isn’t that hard to get.
Those all had the stands milled off and were running Jesel rockers…….. and run cams in the .800” lift range with springs set up at a nominal 2.00” IH.
1.900”-ish IH on std SB heads isn’t that hard to get.
I believe Mullen had mentioned the “battleship” spring. That much lift is far beyond anything I’m capable of affording, but, there was a GT car running 9 1/2 to one compression and 750 lift that was running mid 10’s.
MOPAROFFICIAL
If it has tits, it's a liabilititty.
No.
Earlie A
Well-Known Member
With a factory 59 degree block the geometry on the valve side of the rocker is often not optimal. The geometry on the pushrod side of the rocker is always bad. Correcting the geometry on the valve side at the expense of making the pushrod side even worse is not a good solution. Generally, moving the shaft up (a movement at 90 degrees to the deck face) helps correct things. Moving the shaft away from the valve is not good, it compounds the problems. The pushrod angle goes from already bad to even worse.
There is. What that is I don’t know. Im running stock length valves and a small correction on my junky Speed Master heads and I can get 1.800 installed height.
Im netting .580 lift (I measured it so I know for sure and not making a close guess) and I can still get 165ish on the seat and right at 400ish over the nose. Thats for SFT stuff. And I can still shim .030 more if I need to. That will make me .055 to coil bind.
Most guys run way more installed height than they need (in my opinion) but I don’t like that. And, if you need more installed height than that you can use a .100 long Chevy valve and that will get you 1.900 easily.
But, if I were to do that I could still get a spring that would get me the same seat and open pressures but I’d be almost .200 from coil bind. Would that work. Yes, because that’s far more commonplace than the way I do it.
In my opinion the valve train is far happier and will turn more rpm and be more stable doing it the way I do it than using all that installed height.
Edit: I forgot to say Mike at B3 can tell you within probably .050 or less how far you can go.
Very true. But I’d give up the pushrod side geometry to get the valve off the seat quicker and move it slower through high lift than keep the pushrod side as good as it can be and have the valve move around max lift faster.
Even if it costs another .020-.030 lift.
Last edited:
TT5.9mag
Two atmospheres are better than one
I don’t think I’ve ever set anything up with .200 to coil bind. I try to get em much tighter than that. Have you done that and not had a problem with harmonics?
Earlie A
Well-Known Member
If only it worked that way (all the time). Here's a before and after correction. With 'correction' the rocker ratio went down, lift went down, valve speed went down. This is one example. I'm not making a blanket statement.
MOPAROFFICIAL
If it has tits, it's a liabilititty.
Yeah you're better off using up the spring then having much extra, .050 ish to coil bind is the standard...for the very reason you mention. A lot of things being said are well known...and I'm always amazed at how many people here still don't know much of it. Still nice that there people receptive of it.
PRH
Well-Known Member
Spring material technology has come a long way since I started in this business in 1989.
Back then, if you ran most springs .050” from coil bind they often failed in short order.
The “rule of thumb” at the shop I worked at for endurance oriented applications was around .100” from coil bind.
In the bigger drag stuff I remember there being lots of broken H-11 springs(back when .750-.800” was really a pretty big cam).
Back then, if you ran most springs .050” from coil bind they often failed in short order.
The “rule of thumb” at the shop I worked at for endurance oriented applications was around .100” from coil bind.
In the bigger drag stuff I remember there being lots of broken H-11 springs(back when .750-.800” was really a pretty big cam).
Earlie A
Well-Known Member
I saw a post of yours on another forum. You talked about 'partial coil bind' or something to that effect. You were basically saying that springs do not behave (compress) in a totally linear or uniform fashion. Harmonic waves and manufacturing irregularities can cause parts of the spring to bind even when the whole spring is not at theoretical coil bind. You can expand on that more if you wish. It was a good read.
PRH
Well-Known Member
Rather than have me try and remember what I was talking about, and type endlessly on my phone……..
how about a link?
how about a link?
MOPAROFFICIAL
If it has tits, it's a liabilititty.
A lot of this is relative to what pressures/lift we're talking about. That's the problem with some topics.. they become over generalized.
I wonder how many people on this site are lifting their valve .7 or .800 and wringing it into the red line over 8,ooo rpm ..hard enough and often enough to create the circumstance to break a spring like that.
Yes, but I’ve also run into issues with that distance from coil bind. As long as the cam is pretty slow it seems to be less of an issue.
MOPAROFFICIAL
If it has tits, it's a liabilititty.
Some coils stacking while other not, impacting even.. harmonic disaster
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