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Username Post: what is the maximum lift of stock springs?        (Topic#211971)
chevy355s10 
Frequent Contributor
Posts: 1126
chevy355s10
Age: 25
Loc: lake city,SC
Reg: 07-05-08
03-14-09 07:18 PM - Post#1651731    

i was wondering,what was the maximum lift cam you can use on a sock set of valve springs.
i was told something like,.450".

i was gonna use stock springs to break in my cam with.

the heads are 041 castings,i think.They are on an 88 k1500 5.7L,so you could know better if im wrong.

also,would a cam of only 455 lift cause my valves to separate?....yes,those are stock too.
David B.


Edited by chevy355s10 on 03-14-09 07:19 PM. Reason for edit: No reason given.

 
racecar100 
Contributor
Posts: 123

Reg: 09-04-07
03-14-09 08:46 PM - Post#1651782    
    In response to chevy355s10

.480 is the max lift for stock SBC.

 
leons57belair 
Forum Newbie
Posts: 78

Age: 40
Loc: Moorpark CA
Reg: 09-07-07
03-14-09 08:48 PM - Post#1651784    
    In response to chevy355s10

I am by no means an expert, but I'm running .488 lift on stock springs and it is fine. I have heard that .500 is the max or slightly more than that. I wouldn't go out and spin the motor to the moon though. lol.
Black 57 Chevy Belair 2 door Sport Coupe. 350 engine, edelbrock performer rpm intake, 600 cfm edelbrock carb, K&N filter. Th350 trans.


 
chevy355s10 
Frequent Contributor
Posts: 1126
chevy355s10
Age: 25
Loc: lake city,SC
Reg: 07-05-08
03-14-09 09:48 PM - Post#1651811    
    In response to leons57belair

Thank you guys for the help so far.

when will i have to worry about my valves seperating?

my red line will be around 5000 RPM's.so im not gonna be revving the dog snot out of it.

any input will help LOTS
David B.


Edited by chevy355s10 on 03-14-09 09:59 PM. Reason for edit: No reason given.

 
sedandelivery55 
"8th Year" Gold Supporting Member
Posts: 2736
sedandelivery55
Age: 54
Loc: Moore, OK
Reg: 02-20-02
03-15-09 08:21 PM - Post#1652690    
    In response to racecar100

  • racecar100 Said:
.480 is the max lift for stock SBC.



Uh oh! I'm running a .484 lift cam with stock lifters and roller tip rockers.

  • Quote:
I am by no means an expert, but I'm running .488 lift on stock springs and it is fine. I have heard that .500 is the max or slightly more than that. I wouldn't go out and spin the motor to the moon though. lol.



Good, I won't worry (as much).
Lee

http://www.picturetrail.com

The '55 is home again!
92 GMC Sierra short/stepside
4.3 V6, 5 speed





 
chevy355s10 
Frequent Contributor
Posts: 1126
chevy355s10
Age: 25
Loc: lake city,SC
Reg: 07-05-08
03-15-09 08:32 PM - Post#1652700    
    In response to sedandelivery55

hey,john wayne.

do you know when i will have to worry about my valves seperating? like...at wht lift and spring pressure,er some hing like that?
David B.


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 16222
grumpyvette
Age: 66
Loc: FLORIDA USA
Reg: 03-16-01
03-16-09 04:00 PM - Post#1653321    
    In response to chevy355s10

theres a huge difference between what you can occasionally get away with, and doing the job correctly with the correct valve train geometry and clearances, the clearance you have will vary between small block engines and differant cylinderheads a good deal, .475" is about max on most heads, yes you can sometimes get away with .500 " or slightly more but your taking a huge gamble and a busted valve train or destroyed cam lobe is comonly the result
heres info from my personal data base
http://forum.grumpysperformance.com/viewtopic.php?...
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


Edited by grumpyvette on 03-16-09 04:12 PM. Reason for edit: No reason given.

 
leons57belair 
Forum Newbie
Posts: 78

Age: 40
Loc: Moorpark CA
Reg: 09-07-07
03-18-09 08:56 PM - Post#1655140    
    In response to grumpyvette

I've ran that much lift for over a year now, and no problems at all. My car shifts around 5500 rpm. It's a good idea to check for coil bind and be aware that the valve springs will fatigue faster due to the added stress of the larger cam. I plan on getting better heads sooner than later so I didn't care about valve spring wear. In all honesty, that info about the .500 lift was passed onto me by a memeber on this site, hence the reason i went with .488 and so far so good. Grumpy is the old pro around here though so its usually a good idea to take his advice.
Black 57 Chevy Belair 2 door Sport Coupe. 350 engine, edelbrock performer rpm intake, 600 cfm edelbrock carb, K&N filter. Th350 trans.


 
MikeB 
Senior Member
Posts: 9519
MikeB
Loc: Plano, TX
Reg: 08-28-03
03-19-09 09:23 AM - Post#1655442    
    In response to sedandelivery55

  • sedandelivery55 Said:

Uh oh! I'm running a .484 lift cam with stock lifters and roller tip rockers.

Good, I won't worry (as much).




Just because the springs don't coil bind with .484" lift doesn't mean they are right for your cam. First, you need a .050" - .060" safety margin. Second, spring seat pressure is very important for keeping the valves from bouncing off their seats as they slam closed at high RPMS. I'll bet "high RPM" to a stock spring is about 4500 -- when new!

Stock springs have around 85 lbs seat pressure. A slight performance upgrade, like a CompCams #981 spring, has 105 lbs.

If you do more than cruise around at 2000-3000 RPM, the proper springs will make a significant difference.

1982 C-10 SWB pickup -- Unmolested, original paint, 250 six, 3-speed (soon to be 350 Vortec & TH350)

Sold my 55 sedan in June 2014, having owned it 11 years.


Edited by MikeB on 03-19-09 09:26 AM. Reason for edit: No reason given.

 
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