keep breaking the same spring...any ideas?
10-10-2005, 09:50 AM
#1
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keep breaking the same spring...any ideas? Ok, a little background:
The motor is a 408ci with a 246/248 .603/.615 114lsa cam.
I have chromemoloy (spell check) pushrods 7.350,
Yella Terra rockers 1.7 ratio, [stock valvecovers which i found markings from the rockers hitting it, making a tapping sound like bad pushrod (YES, i finally found the cause of that noise, has been driving me nuts!!!)]
Ferrea endurance springs good to .670 lift and ferrea valvetrain pieces (keepers, retainers, etc.)
Initially, i shattered the exhaust spring on cylinder #2 (passenger side, first cylinder) and when i took all of them out, i found another three springs broken.
Anyways, i replaced the springs for a better set and after two months or so, the motor started acting funny and long and behold, the same exhaust cylinder #2 spring is broken, .........AGAIN!!!! AARRRHHHHHHHHH!!!!!
I havent taken here to the track and im very picky with the go pedal, i always wait until she is warmed before any spirited driving though. So, I stumped!!!
I took the rockers and checked the preload on the rockers...everything was find. Found about 3/4 turn, roughly .040 preload. The pushrods seemed ok but im not entirely sure. I rolled them on a glass table and a granite top (kitchen) and them seemed to wobble, but very, very little. You had to really focus on them. I figured that maybe the "rollin" surfaces" weren't subjected to the kind of measurement precision a pushrod is but that did stick in my mind.
however, since they are hardened pushrods, im not sure how i could bend a set of these from what i have been told. I tried the pushrods from cylinder #1 and them seemed to roll exactly the same as the others, with a little wobble.....so maybe its not the pushrods...or....
Aynways, what do ya'll think? Im gonna try a differnt set of springs (comp 921) and a new set of pushrods, just ot be certain.
But, is there anything mechanical that could be causing this shananagans besides a bent pushod, or bad set of springs?
The motor is a 408ci with a 246/248 .603/.615 114lsa cam.
I have chromemoloy (spell check) pushrods 7.350,
Yella Terra rockers 1.7 ratio, [stock valvecovers which i found markings from the rockers hitting it, making a tapping sound like bad pushrod (YES, i finally found the cause of that noise, has been driving me nuts!!!)]
Ferrea endurance springs good to .670 lift and ferrea valvetrain pieces (keepers, retainers, etc.)
Initially, i shattered the exhaust spring on cylinder #2 (passenger side, first cylinder) and when i took all of them out, i found another three springs broken.
Anyways, i replaced the springs for a better set and after two months or so, the motor started acting funny and long and behold, the same exhaust cylinder #2 spring is broken, .........AGAIN!!!! AARRRHHHHHHHHH!!!!!
I havent taken here to the track and im very picky with the go pedal, i always wait until she is warmed before any spirited driving though. So, I stumped!!!
I took the rockers and checked the preload on the rockers...everything was find. Found about 3/4 turn, roughly .040 preload. The pushrods seemed ok but im not entirely sure. I rolled them on a glass table and a granite top (kitchen) and them seemed to wobble, but very, very little. You had to really focus on them. I figured that maybe the "rollin" surfaces" weren't subjected to the kind of measurement precision a pushrod is but that did stick in my mind.
however, since they are hardened pushrods, im not sure how i could bend a set of these from what i have been told. I tried the pushrods from cylinder #1 and them seemed to roll exactly the same as the others, with a little wobble.....so maybe its not the pushrods...or....
Aynways, what do ya'll think? Im gonna try a differnt set of springs (comp 921) and a new set of pushrods, just ot be certain.
But, is there anything mechanical that could be causing this shananagans besides a bent pushod, or bad set of springs?
10-10-2005, 10:48 AM
#2
the push rods should not be bent at all....if push rods are bent its possible that some valves are bent. did you make sure that the vavles didnt hit the pistons with that cam? its BIG you know. the vavles are open alot and for a long time. that might explain the pushrods but i am not sure of the cause of the broken springs. do you have the right preload on the springs and not have them shimmed up too tight? if so i dont know what to tell you.
10-10-2005, 10:53 AM
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Those pushrods are easier to bend than you would think, since they are designed to bend before a much more expensive valvetrain part breaks. That being said, I've never really had my pushrods wobble at all when I rolled them. I usually watch the hole at the end and see if there's any up-down movement. Did you check pushrod length to see if it's ok? Aside from that I can't see how that same spring would be breaking over and over again, especially with the lift those spring are made to handle, provided they are installed at the proper height.
Last edited by LSUxBlake; 10-10-2005 at 12:01 PM.
10-10-2005, 02:40 PM
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the preload is fine. The pushrods are at the correct length and the height is fine.....i know i pretty much ruled just about everything...but i double checked everything...
i think that the springs are just not right...... will get back to ya'll
thanks for the repies......anyone else?
i think that the springs are just not right...... will get back to ya'll
thanks for the repies......anyone else?
10-10-2005, 02:45 PM
#7
What i was getting at with the stock rockers thing, some rockers have clearance issues with aftermarket valvesprings and they'll hit the retainer. Maybe the rockers are even twisting side to side or something like that. I can't think of anything else that would break the same valvespring twice in a row, except a coincidence.
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10-10-2005, 04:03 PM
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Originally Posted by P Mack
What i was getting at with the stock rockers thing, some rockers have clearance issues with aftermarket valvesprings and they'll hit the retainer. Maybe the rockers are even twisting side to side or something like that. I can't think of anything else that would break the same valvespring twice in a row, except a coincidence.
Usually, you can see marks on the retainer when the rocker has been hitting it, I had that happening when I was running a larger diameter spring in an old setup. You may want to check that.
