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overdeveloped beater
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Discussion Starter #1 (Edited)
I did some parts scrounging while looking into sources for upgraded valvesprings for either higher RPM, hotter cams or both. (perhaps even bOOst....) I never liked the idea of running a big shim under a DOHC valve spring to make height so things would work in a SOHC head, this is what Supertech does.....

I found that AVCS equipped SOHC heads use springs rated higher than the non AVCS heads. It's not by much, but it's in the ballpark of what Supertech is offering, but it's got a Subaru part number! The installed height is the same and the specs for full lift (height) match as well. Retainers still have the same PN, so they don't need changed. I've ordered a set to use in my 12:1 motor and will post up what I find (along with pictures).

Here's the measurements taken from the service manuals:

Measurement - non/avcs - avcs

Free length - 54.30mm(2.1378") - 55.2mm(2.173")
Installed height - 45mm(1.772") - 45mm(1.772")
Full lift height - 34.7mm(1.366") - 34.7mm(1.366")
Tension @ install height - 22-25kg/mm(48-55lb/in) - 24-27.6(52.9-60.8lb/in)
Tension @ full lift - 54-59kg/mm(119-130lb/in) - 59.1-65.3kg/mm(130.3-143.9lb/in)

SPRING PART NUMBERS:
non-avcs: 13217AA261
avcs: 13217AA390

RETAINER:
Same PN of 13209AA180

Keeper (collet, locks, etc...)
Same PN of 13210AA020

I still need coilbind measurements, which I will provide in this post when I measure them.
 

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v8
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Storm - I would kiss you if you're right. I just went through such a hassle with supertec and their "need seats and retainers" scam i decided to just run stockers but I'd like heavier spring to keep the float down.

Sent you a text - I have a set of heads sitting in my shed that might be the same as the ones you speak of.
 

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overdeveloped beater
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Discussion Starter #6
I believe it was Rokkit's pictures that sparked the curiosity in me actually...... There are pics floating around on the site of AVCS heads that have springs marked with white paint instead of the green in normal SOHC heads. I looked up the specs and the installed height is the same, as well as the full lift height. The retainers carry the same part number, so the diameters (I am assuming) must be the same too.

If they're taller in free height, the extra pressure will come from that as the rate goes up as any spring is compressed (in linear or progressive fashion, depending on the spacing between coils and wire diameter). This is basically the same situation as I ran into when fitting STi valve springs (and retainers) into EJ25D heads. That experiment worked like a champ, so I expect this experiment to produce similar results.

When the springs get to me, I'll post pics of them side by side, perhaps both loaded up on a spring checker for comparison sake, and add the critical detail not listed in the FSM.......COILBIND height. Stay tuned for more info as I develop it! And please.....feel free to contribute if you have AVCS springs available now to do some measuring!
 

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v8
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Yeah I have some springs sitting in heads but my valve spring compressor is MIA. I should go get another one.

I think if you were using stock cams you wouldn't need to worry too much about the coil bind point, however, the 2000 Deltas do have a higher lift so I'd worry about how far the valve protrudes through the head. If it's significantly longer/shorter than the early 2000 SOHC, it could be an issue.
 

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overdeveloped beater
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Discussion Starter #8 (Edited)
Edited first post with measurements. It's about a 10% difference. The coilbind measurements will determine how much lift at the cam they will be able to handle. That is, once we determine the actual rocker arm ratio. Different values have been published and I haven't measured this for myself.
 

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How do you determine coil bind max? Visually? or when the valve spring tension plateaus?
 

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overdeveloped beater
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Discussion Starter #10
Coilbind is just how it sounds.....when the coils actually touch each other. Safe to say that you don't ever want to get there.....broke stuff happens real quick!
 

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Yeah I know what it is I just wasn't sure to what extreme you could run a valve spring. I know progressive suspension springs can be designed to coil bind for a reason - assuming valve springs are not progressive... I didn't know if there was a "max" amount of bind. I assume none is the correct answer.
 

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overdeveloped beater
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Discussion Starter #13
That's some good stuff right there! I've seen similar videos, but that's really good footage.
 

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'95 work in progress
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That's some good stuff right there! I've seen similar videos, but that's really good footage.
I agree. So good in fact that I am going to save it for customers who do not understand the event. Visual is always an easier teacher. Thanks for posting Skidd!!
 

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overdeveloped beater
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Discussion Starter #16
Yeah, and I haven't totally excluded the idea of using the P2 EJ22 heads I have on top of that!!!!! I'd have to run jet fuel....but damn it oughtta be a torque monster if I weren't such a pu$$y.....
 

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GF OBS-T, GM RS EJ20, SF EJ20
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Hey Jay aren't you running a standalone ECU, super high compression may be an excuse to run E85 if it is available in your neck of the woods...

Curious to see if/how these valve springs work-out.
 

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overdeveloped beater
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Discussion Starter #19
Right next to your membership..... lol.....


I'm still waiting on the springs to get to me. As soon as I get them, I will measure free length, coilbind and confirm pressures at those 2 points.

The motor as a whole, needs to be completed ASAP, so I can get on the dyno before a major event on the 4th of july weekend......
 
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