broken valve springs

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0ld school

0ld school

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on my 580" with 572-13 heads, all of my inner springs broke. some into 3-4 pieces. i have the jessel set up. i only have about 500 miles on them as this is a street car.

the springs i use now are k motion 1000h,s. is there a better spring? i have heard that the k motion springs would break eventually. it is a solid roller with 1.7 rockers. the cam specs:
.800"/.750" 282/290 @.050.

the k motion 1000h specs:
1.625"
265# @2.00"
790# @1.250"

i would need something close to the same specs. i will be changing them with the heads still on. this is a street car, so reliabilty is the main concern. thanks...
 
0ld school said:
on my 580" with 572-13 heads, all of my inner springs broke. some into 3-4 pieces. i have the jessel set up. i only have about 500 miles on them as this is a street car.

the springs i use now are k motion 1000h,s. is there a better spring? i have heard that the k motion springs would break eventually. it is a solid roller with 1.7 rockers. the cam specs:
.800"/.750" 282/290 @.050.

the k motion 1000h specs:
1.625"
265# @2.00"
790# @1.250"

i would need something close to the same specs. i will be changing them with the heads still on. this is a street car, so reliabilty is the main concern. thanks...
Click to expand...

That cam is not really a street friendly cam based on that lift and duration. Street driving something like that is going to wear out ANY spring on the market quickly.
If it was mine, with that much cam I'd only run a PAC spring and give them all the info on the cam, rpm range, etc....I'm thinking seat pressure should be closer to 300lbs. and open is about right. Also, what lash are you using?
 
ou812 said:
That cam is not really a street friendly cam based on that lift and duration. Street driving something like that is going to wear out ANY spring on the market quickly.
If it was mine, with that much cam I'd only run a PAC spring and give them all the info on the cam, rpm range, etc....I'm thinking seat pressure should be closer to 300lbs. and open is about right. Also, what lash are you using?
Click to expand...

thanks brian...i dont mind wearing out springs, i just dont want them to break into pieces. i use .025" for the lash.

should i be using a drag or endurance spring?
 
0ld school said:
thanks brian...i dont mind wearing out springs, i just dont want them to break into pieces. i use .025" for the lash.

should i be using a drag or endurance spring?
Click to expand...

That will be up to PAC. Talk to Chris Osborne. My guess is VascoJet material.
 
What pushods are you running? With the street factor, what's your "normal" rpm operating range? Was the 1.7 rocker ratio taken into account when the springs were spec'd? With such a short time on them, I'd also be very concerned with valvetrain harmonics and bounce from too little pressure. I wouldn't expect use to break them. Heat might wear them out, but they shouldn't break.
 
moper said:
What pushods are you running? With the street factor, what's your "normal" rpm operating range? Was the 1.7 rocker ratio taken into account when the springs were spec'd? With such a short time on them, I'd also be very concerned with valvetrain harmonics and bounce from too little pressure. I wouldn't expect use to break them. Heat might wear them out, but they shouldn't break.
Click to expand...

i dont mind wearing them out, but i should not be breaking them. i use manton pushrods. 3/8" .120" wall.
 
K-Motion's are notorious for breaking instead of going soft.
I would think if you can get a 7/16 rod in there you should!
Brian
 
ou812 said:
K-Motion's are notorious for breaking instead of going soft.
I would think if you can get a 7/16 rod in there you should!
Brian
Click to expand...

thats what i thought too. terry at manton said the 3/8 was all that i needed :scratch:.

i also heard the same thing about the k motions. i have them on 3 500" motors, and they have been reliable. but those are milder springs. i'm wondering if the 1.7 rockers might be to aggresive....
 
0ld school said:
thats what i thought too. terry at manton said the 3/8 was all that i needed :scratch:.

i also heard the same thing about the k motions. i have them on 3 500" motors, and they have been reliable. but those are milder springs. i'm wondering if the 1.7 rockers might be to aggresive....
Click to expand...

That depends on the lobes...do you have any info about them?
 
ou812 said:
I believe they use Comp...are there any lobe #'s or any info you can post?
Click to expand...

This Cam is made by CMI, the specs from my cam sheet:
lobe separation 112
valve overlap 61.4
Intake: valve open 32 BTDC
Centerline 108 ATDC
Valve close 69.4 ABDC
Duration 281.4
Lobe lift .469
Valve lift .704
lobe area 42.72 in * deg
Exhaust:
valve open 80 BBDC
centerline 116 BTDC
valve close 29.4 ATDC
duration 289.4
lobe lift .441
valve lift .661
lobe area 41.76 in * deg
 
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