Valve Springs too Much?

[hotrod1968]

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..

[BOOT]

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...

[BOOT]

Oh and what type of vortecs, factory or aftermarket? Cause idk bout .588 lift

[rebelrouser]

My personal opinion is that they would be too stiff, going off of the reply from BOOT.
On your other question, if you have a spring checker, to test your pressures, and calculate the rate, I have swapped out inner springs many times, and run only the main valve spring many times as well. Somebody may give reasons why it should not be done, but I have done it scores of times.

And I used to have access to a expensive spring tester, but all I use in my home shop is one of the cheap liquid filled type you can clamp in a vice, seems to get it close enough for me. And when I checked it with the expensive tester it was pretty close. You can also buy a test spring to check calibration for not much money.

I think recently there was a thread about getting recommendations from cam companies about exactly how much spring pressure would be required.

[BOOT]

My personal opinion is that they would be too stiff, going off of the reply from BOOT.
On your other question, if you have a spring checker, to test your pressures, and calculate the rate, I have swapped out inner springs many times, and run only the main valve spring many times as well. Somebody may give reasons why it should not be done, but I have done it scores of times.

And I used to have access to a expensive spring tester, but all I use in my home shop is one of the cheap liquid filled type you can clamp in a vice, seems to get it close enough for me. And when I checked it with the expensive tester it was pretty close. You can also buy a test spring to check calibration for not much money.

I think recently there was a thread about getting recommendations from cam companies about exactly how much spring pressure would be required.

I have run just the outers as well but based on the 1.9 install height my bet is still to much. Also idk if factory vortecs can be cut to fit a 1.55 springs? Still not sure what the exact heads are so idk

[swampbuggy]

About 45 years ago a gentleman that i looked up to and went to the local 1/4 mile asphalt Stock Car track with decided to remove the inner valve springs thinking that the car might run a little quicker. This was a 223 Ford inline 6 cyl. with stock Ford steel valves turning appx. 6000 . We were having problems dropping a valve ( can not remember which side ) . When i called the Camshaft person ( one of the Iskenderian's ) and told him what was going on, the first thing he ask me was....Are you running the inner springs ? You might ask were the valves floating ? No they were not to the ear, however they were no doubt bouncing in excess or something to be tearing the tip off. Something to think about. Mark H.

[hotrod1968]

Thank you for the replies, thats very helpful to know. The heads are warmed over 906’s, and the valve guide boss is chewed down and machined for positive seals, so I hope I’ll make it on lift. I’ll scrap the idea of using these PAC springs, I’ll cut corners somewhere else. Thanks again for taking the time to respond

[BOOT]

Thank you for the replies, thats very helpful to know. The heads are warmed over 906’s, and the valve guide boss is chewed down and machined for positive seals, so I hope I’ll make it on lift. I’ll scrap the idea of using these PAC springs, I’ll cut corners somewhere else. Thanks again for taking the time to respond

Take the retainer and locks that you plan to use and measure on a valve in the head how much room you have between the seal top and retainer center bottom. They show it being measured a bit down this page here with the clearance spec and there is other useful info https://blog.dartheads.com/how-to-set-u ... 0clearance.

[Geoff2]

Lots of mistakes on the Summit site.

[Monza355]

Howards spring number -98541 works very well with these cast core cams. But it has a 1.800” installed height for 180 lbs seat pressure and 475 lbs/in

[F-BIRD'88]

Comp 977 or K motion K800 both suitable 1.46" dual springs for this.
Do not use less than what Comp recomends for this solid street roller cam.
It is on the modest side as it is. use 1.5 rockers.

What ever you read on Summit about springs for this are wrong.. Looks like springs for a moderate hyd roller at best.

Call Comp cam help for correct spring advice. not Summit.
The Summit statements are in error for this.

Set up the installed height at 1.80" intake and 1.825" exhaust on either 977 or K800 springs for this. (177# to 190# seat)

You can set the lash cold a bit tighter than the hot lash spec. .012"-.014" seems to work... Then check hot and note.
The comp 977 springs are (relative) modest to keep wear in check. But you don't want less on these XSR cams
using the cast cam core.. It works if you stick to the plan.
Comp can custom grind on steel -9 core and change the LSA and more if desired. Thats what the telephone is for.
This series work very well when used as designed intended.
These are catalog marketing examples. If you bother to make a phone call these guys are very good at getting the cam and combo right for the job you are doing.
They are custom cam company every day.

Do not use more than 1.5 rockers on this specific cam with the comp 977 springs..

[BillK]

Lots of mistakes on the Summit site.

That is absolutely true. I tell my customers to never trust the technical information there. I always go to the actual manufacturers site or call them.

[BOOT]

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

Lots of mistakes on the Summit site.

That is absolutely true. I tell my customers to never trust the technical information there. I always go to the actual manufacturers site or call them.

I agree again

[BOOT]

Thank you for the replies, thats very helpful to know. The heads are warmed over 906’s, and the valve guide boss is chewed down and machined for positive seals, so I hope I’ll make it on lift. I’ll scrap the idea of using these PAC springs, I’ll cut corners somewhere else. Thanks again for taking the time to respond

Almost forgot to ask are you installing screw in rocker studs?

[BOOT]

Figured might as well make a quick google with "PAC 1243" and then peeps can see for themselves, it looks like Summit got it right this time(link below). Now of course I have found their(Summit Racing) info to be wrong several times and deff don't follow the advise in the questions or reviews below the parts w/o checking into it more yourself(that goes for any advise and even MINE!). Still kudos to Summit this time

https://www.racingsprings.com/index.php ... 11301.html