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Valve Spring Choice for Solid Roller Street/Strip

General engine tech -- Drag Racing to Circle Track

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F-BIRD'88
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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by F-BIRD'88 » Wed Dec 04, 2019 1:30 pm

If I was going to run a comparable comp xr cam (eg: comp xr286r-10 cam)on that with 1.7-1.6 rockers and nitrous to 7500 rpm I would upgrade the springs I'd use for that beyond comps default recomendation.
There is a 1.46" Kmotion spring that fits that hd street higher rpm higher rr requirement .
It is not enough for your BullEt cam.

The Isky springs will work very well for you.
You'd need to inspect your valvetrain regularly looking for wear and tear REGUARDLESS.
You want to catch any roller bushing wear early and rebuild
BEFORE bad things can happen.
That is the purpose of the bushed bearing roller lifter.

This engine should run pretty strong.
Good luck..

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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by F-BIRD'88 » Wed Dec 04, 2019 1:34 pm

You could if you want measure your net seat to seat duration with your planned tighter lash setting.
During cam install. .

I have run a few of this stuff including the xr cams at tighter lash settings to good effect.

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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by n2omike » Wed Dec 04, 2019 1:40 pm

Well, I looked up the PAC 1530 Valve Springs. They are listed at $53.13 each... (nitrided, nano-peened) Spring Seats/Locators are either $3.97 or $5.10 each depending on guide size. There are three retainers... Tool Steel is $19.17, one Titanium is $13.10 each, the other is $22.11. Same specs. Not sure about the differences in the two Ti pieces, except the cheaper one is 400 series 'mini-8' and the other is 500 series 'mini-8'... whatever that means. Didn't look up the locks.

1530 Springs $53.13 x 16 = $850.08.... plus all the related hardware is around $1,200 to $1,300. They are listed as 'circle track' springs, so I'm sure they have longevity in mind. They install at a lower seat pressure, but have a higher rate... 560 vs 500 lb/in. Small diameter, at only 1.284". They don't list its mass, but has to be a lot lower than a 1.56" offering... plus the smaller retainer.

Will try the existing Isky 'old tech' springs... as they are new (in 2011) and I already have them. I'll keep the PAC springs in mind in case these appear to be insufficient, or for a future upgrade.

Edit...
I was writing this post while you were making your replies, F-BIRD.

Thanks for the insight!
Last edited by n2omike on Wed Dec 04, 2019 1:45 pm, edited 1 time in total.

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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by F-BIRD'88 » Wed Dec 04, 2019 1:42 pm

Orr89rocz wrote:
Wed Dec 04, 2019 12:57 pm
Cam looks very similar to a comp cams RT lobe which is pretty aggressive but searching here bigjoe said he used them in limited street use deals before.

Found this posted but no idea what specific lobe it was

“Currently on dyno with a small block RT intake with a 1.65:1 rocker and 128g valve(i know its heavy) and with a PAC 1385 set at 275lb seated and 660open. This thing is out of control by 7700...”
This is interesting and exactly what I am getting at.
good report.

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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by n2omike » Wed Dec 04, 2019 2:18 pm

F-BIRD'88 wrote:
Wed Dec 04, 2019 1:42 pm
Orr89rocz wrote:
Wed Dec 04, 2019 12:57 pm
Cam looks very similar to a comp cams RT lobe which is pretty aggressive but searching here bigjoe said he used them in limited street use deals before.

Found this posted but no idea what specific lobe it was

“Currently on dyno with a small block RT intake with a 1.65:1 rocker and 128g valve(i know its heavy) and with a PAC 1385 set at 275lb seated and 660open. This thing is out of control by 7700...”
This is interesting and exactly what I am getting at.
good report.
Got me curious, so I weighed my parts...
2.08 11/32 Intake Valve: 131 grams
Titanium 10 deg retainer: 17 grams
10 degree steel locks: 7 grams

Isky 9385 Spring: 158 grams

Would be curious to know what the lift was in the above Big Joe example... but knowing him, likely large by huge. lol
Well, I did some math. With a difference of 660 - 275 lb = 385 lb... and a rate of 525 lb/in... it comes out to 0.733" lift... so a sizeable cam.

My numbers are 245 closed and 595 @ 0.700 lift.

And, wow.... Based on the specs, my Bullet lobes have nearly identical intensity to the mentioned Comp RT lobes!
Based on lift, I'd say the lobes on Big Joe's cam were in the bottom section of the series... calculated 0.733" lift using 1.65 rockers.

Mine again... compared to the Comp RT lobes.
(solid roller)
279/291 @ 0.020"
249/258 @ 0.050"
172/177 @ 0.200"
0.4120"/0.4315" lobe lift
0.700"/0.690" lift with 1.7/1.6 rockers
110º Lobe Separation
0.018"/0.022" lash

Image

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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by F-BIRD'88 » Wed Dec 04, 2019 2:33 pm

Id be analysing the lash ramps and the accel opening flank and decel closing flank in the areas between lash point and .020" lifter rise. Some 'hi torque design cam lobes don't even have a real opening lash ramp and the closing side is fast fast. (vs a "hi rpm cam lobe design)
These can be quite asymetric open close too.

This cannot be seen just by the .020"---.050".--.0200" and max lobe lift numbers.
The running dynamics st 7500 rpm can be quite different.

With enough specific lobe(s) design info a guy like CamKing could analyse this..

He's pretty sharp.

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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by Cobra720 » Wed Dec 04, 2019 7:03 pm

n2omike, I'm using the compcam slightly bigger than the XR 286R (custom) mechanical street roller on a billet core in my 408w, with Isky #9315 valve springs 1.885/1.890 seat height 228/232lbs 538lbs@.630 lift Manton .118 wall 5/16 series 4 pushrods, Crower SS rockers with a Brodix stud girdle. Lashed HOT .016/.016 Morel bushed lifters on the street and autocross. Zero issues.

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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by bob460 » Wed Dec 04, 2019 7:19 pm

Total weight of Isky 9385 Spring with retainer and locks 180 grams.

Total weight of pac 1530 Spring with retainer and locks 130 grams.

50 grams weight saving.................That's crazy imagine at 7500rpm what that extra 50 grams is doing........here is a good watch!!!


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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by n2omike » Wed Dec 04, 2019 8:16 pm

bob460 wrote:
Wed Dec 04, 2019 7:19 pm
Total weight of Isky 9385 Spring with retainer and locks 180 grams.

Total weight of pac 1530 Spring with retainer and locks 130 grams.

50 grams weight saving.................That's crazy imagine at 7500rpm what that extra 50 grams is doing........here is a good watch!!!
Very good point... but a 'little' misleading. The entire valve/retainer and locks are moving the entire 0.700" distance with every lift cycle. As for the spring, the only part moving that far is the very top. The bottom doesn't move at all, and the middle probably moves roughly half that much. As a rule of thumb, to get weight savings, I'd probably take the difference in spring mass, and divide that by two.

So... Total reciprocating mass would be (valve + retainer + locks) + (half of total spring mass)

Isky 9385 (131 + 17 + 7) + (158/2) = 234 grams

If that is a PAC 1350 in the video (not, but likely similar)
Small Spring (131 + 8.6 + 2.4) +(117/2) = 200.5 grams

So, 234 - 200.5 = 33.5 grams less reciprocating mass. This is a 14.3% reduction in reciprocating mass. If that directly correlates to rpm gain, and it would go out of control at 7500 rpm with the old stuff, that would be 7500 x 1.143 = 8572 rpm. However, this is taking a lot of liberties... as it is surely not a direct relationship. lol If we saw it as being able to use less seat pressure, it would be the initial of 245 x 0.857 = 210 lbs for the same valve control. (more likely)

Still, a significant reduction. It's also taking into account steel 10 degree locks with the Isky, and smaller Titanium locks with the smaller springs.

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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by bob460 » Wed Dec 04, 2019 9:23 pm

It is a psi spring in the video......1.31.......so the pac 1530 might even way less!!(maybe, that's why i emailed pac for that information)

In the video the class was running 240 on the seat, and these will run at 180 seat.........and last 4 times longer. Money well spent IMO.

I'm going to be using these 1530 pac springs in my ford big block 545ci.......max 6800rpm street car. Will see how it works out.

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Re: Valve Spring Choice for Solid Roller Street/Strip

Post by digger » Wed Dec 04, 2019 9:44 pm

n2omike wrote:
Wed Dec 04, 2019 8:16 pm
bob460 wrote:
Wed Dec 04, 2019 7:19 pm
Total weight of Isky 9385 Spring with retainer and locks 180 grams.

Total weight of pac 1530 Spring with retainer and locks 130 grams.

50 grams weight saving.................That's crazy imagine at 7500rpm what that extra 50 grams is doing........here is a good watch!!!
Very good point... but a 'little' misleading. The entire valve/retainer and locks are moving the entire 0.700" distance with every lift cycle. As for the spring, the only part moving that far is the very top. The bottom doesn't move at all, and the middle probably moves roughly half that much. As a rule of thumb, to get weight savings, I'd probably take the difference in spring mass, and divide that by two.

So... Total reciprocating mass would be (valve + retainer + locks) + (half of total spring mass)

Isky 9385 (131 + 17 + 7) + (158/2) = 234 grams

If that is a PAC 1350 in the video (not, but likely similar)
Small Spring (131 + 8.6 + 2.4) +(117/2) = 200.5 grams

So, 234 - 200.5 = 33.5 grams less reciprocating mass. This is a 14.3% reduction in reciprocating mass. If that directly correlates to rpm gain, and it would go out of control at 7500 rpm with the old stuff, that would be 7500 x 1.143 = 8572 rpm. However, this is taking a lot of liberties... as it is surely not a direct relationship. lol If we saw it as being able to use less seat pressure, it would be the initial of 245 x 0.857 = 210 lbs for the same valve control. (more likely)

Still, a significant reduction. It's also taking into account steel 10 degree locks with the Isky, and smaller Titanium locks with the smaller springs.
1/3 of the spring mass is actually a lot closer to the mark in terms of mass participation.

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