Valve Springs too Much?

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Re: Valve Springs too Much?

Post by LSP »

hotrod1968 wrote: Wed Feb 03, 2021 7:41 pm Looking for some advice on valve springs for a sbc. Putting together a 11:1 iron vortec headed solid roller thing for a crazy street car, looking at a comp 12-773-8 solid roller with a 977-16 spring. An answer from comp on Summit’s site suggested this:

For street use, 120-140 lbs closed valve spring pressure and 300-350 lbs at max lift of the camshaft. Max closed pressure would be 165 lbs and 385 lbs at max lift

Cam has a 3200- 7000rpm range
254/260 @ .050”
.582/.588 lift

977-16 spring has the following specs
OD: 1.460
Max Lift: .700
Seat PSI: 160@1.850
Open PSI: 440@1.250
Coil Bind: 1.200

I have PAC 1243 springs taken from a set of AFR 1458 heads which I think are way too much:
1200 Series Dual Spring
1.55″ OD
.812″ ID
.700″ Max lift
550 lbs./in. Rate
1.053″ Coil Bind Height

This is probably a foolish question, but assuming I’m right about these being too nutty for my application, can I run without the inner spring? Is there a way to know what effect this would have on the spring pressure? Or is this just no good all over? I’m trying to do this on the cheap with as many collected parts on hand as I can. Poor mans racecar. Hence the ported to death vortecs..
Can't give a spring recommendation with enough info -

What are the duration #'s @ .020"?
Steel valves?
Peak rpm?
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Re: Valve Springs too Much?

Post by F-BIRD'88 »

That PAC spring will destroy a sadi cast roller cam core.
These are race roller springs.
Do not use on this cast cam core.
If you want to run such spring get the cam ground on a steel roller cam core "-9".

This is exactly how people can run into problems with sadi cast street roller cams. Stick to Comps recomended seat and open spring force range for the -8 sadi cast cam core.
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Re: Valve Springs too Much?

Post by rebelyell »

F-BIRD'88 wrote: Thu Feb 04, 2021 2:06 pm That PAC spring will destroy a sadi cast roller cam core.
These are race roller springs.
Do not use on this cast cam core.
If you want to run such spring get the cam ground on a steel roller cam core "-9".

This is exactly how people can run into problems with sadi cast street roller cams. Stick to Comps recomended seat and open spring force range for the -8 sadi cast cam core.
yes.
JMO, but I wouldn't choose a cam with a suggested power range of 3200-7000 for a street car.
that sadi cast roller cam scam from most makers is a ripoff, essentially same cores as flat tappet but charging what were billet steel prices. YMMV
summit has recently introduced a four pn selection of USA made billet steel hydraulic roller cams; all Under $250, all have step-nose
https://www.summitracing.com/search/bra ... =Ascending
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Re: Valve Springs too Much?

Post by CamKing »

rebelyell wrote: Fri Feb 05, 2021 11:37 am summit has recently introduced a four pn selection of USA made billet steel hydraulic roller cams; all Under $250, all have step-nose
Those are made from the same 1050 steel, as the OEM cams are made, and finished on the same high speed production machines. They're fine for a low spring pressure hydr roller, but that's about it.
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Re: Valve Springs too Much?

Post by Walter R. Malik »

CamKing wrote: Fri Feb 05, 2021 12:01 pm
rebelyell wrote: Fri Feb 05, 2021 11:37 am summit has recently introduced a four pn selection of USA made billet steel hydraulic roller cams; all Under $250, all have step-nose
Those are made from the same 1050 steel, as the OEM cams are made, and finished on the same high speed production machines. They're fine for a low spring pressure hydr roller, but that's about it.
The Ford Motor Company O.E.M. steel cores seem to hold-up MUCH better than the SADI cores do.
The hardening of those O.E.M. cores is deeper also.
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Re: Valve Springs too Much?

Post by hotrod1968 »

Thank you all for your replies, I decided against the Comp cam and went with a Crower 00427 made from 8620 steel.
https://www.crower.com/camshafts/chevy- ... illet.html

INT/EXH - Dur @ .050” Lift: 260°/266° RR: 1.5/1.5 Gross Lift: .585”/.597” LSA: 112° RPM: 3250 to 7250 Redline: 7750

These are the specs for what Crower recommends for a spring:
Installed Height (in):
1.900 in.
Seat Pressure at Installed Height (lbs):
166 lbs.
Open Height (in) (app):
1.200 in.
Open Pressure (lbs):
469 lbs.

This may be a foolish question, but I’m trying to run big dogs, small budget. I measured the PAC springs individually, and was wondering if it is unwise to try to use the outer ONLY. I suspect there are reasons it would be unwise, but I wasn’t sure. The figures for the outer by itself are below:
Outer spring 175 @ 1.900
410 @ 1.200

Could someone please advise on whether I could swing this? I don’t plan on wringing it out, wont be going above 6500rpm, so I was hoping I could sacrifice the 60lbs over the nose.

Thanks for reading
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Re: Valve Springs too Much?

Post by Monza355 »

You say you are on a budget. It would have been better to buy the correct springs for the comp cam assuming you already have that camshaft.

I would not run the outer spring only with that little open pressure. With a single spring with not enough pressure you are dramatically increasing the risk of dropping a valve.

The Howards spring part #98541 I recommend for the comp camshaft will also work with you Crower street roller camshaft. Based on the information from crower. I have ran a Crower cam from the same street roller series with K-Motion K-800 spring and that worked very well.

Begin on a budget I would not afford to loose a complete engine over a 2-300$ spring package. My advice is to do it once and do it right !
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Re: Valve Springs too Much?

Post by F-BIRD'88 »

A set of K-800 springs cost how much?
Avoid playing games.
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Re: Valve Springs too Much?

Post by hotrod1968 »

Thank you all for your input. I was only considering the Comp Cam, I decided against buying it due to the metallurgy, and the Crower seemed a bit hairier. Thats sound advice. I’ll use the K-800’s you suggest. Thanks very much for taking the time to reply.
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Re: Valve Springs too Much?

Post by af2 »

BOOT wrote: Wed Feb 03, 2021 8:42 pm A quick look on Summit shows me those PAC 1243 springs have a 1.9 install height with 240lb seat, I'd check PAC site to be sure but based on that info I'd say they are very too much. Even if you could install them at 1.9 on vortec heads you'd be 563.4lbs open on the exhaust LOL

Maybe I'm wrong and I will never claim to be an expert at anything cam or valvetrain but...
I have a set of good springs that floated at 7500. 180 seat and never again!
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Re: Valve Springs too Much?

Post by BOOT »

af2 wrote: Wed May 12, 2021 6:45 pm I have a set of good springs that floated at 7500. 180 seat and never again!
Quickly looking again at the op post, he said for street and then in a more recent post...

hotrod1968 wrote: Wed May 12, 2021 10:23 am I don’t plan on wringing it out, wont be going above 6500rpm, so I was hoping I could sacrifice the 60lbs over the nose.
I mean the cam is solid roller but it doesn't sound like he wants to push it that high anyway
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Re: Valve Springs too Much?

Post by rustbucket79 »

Screw in studs and guide plates on these heads?
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Re: Valve Springs too Much?

Post by hotrod1968 »

Yes screw in studs guide plates and .080 wall pushrods, but right now I only have 3/8” ARP and Comp 1.52 Ultra Pro Magnum chromoly rockers. I’ve been really staring that one down too. I’m cutting some corners, not sure if I want to risk running 3/8” studs. Most of this stuff is kicking around, I probably should have established that. I’m kind of piecing together something from bits from other jobs. I can’t actually afford to play, I’m just trying to.
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Re: Valve Springs too Much?

Post by rustbucket79 »

Stud girdle would be a nice upgrade but on a street roller you’ll be fine with the hardware you have.
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