Keep bending push rods! Help Please!
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Joined: Mar 2002
Posts: 53
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From: Clovis New Mexico
Keep bending push rods! Help Please!
Have a 350 with vortec heads with upgraded springs to handle up to .490 lift, 1.6 ratio comp cams self aligning roller tip rockers, and cam with .442 lift. I have adjusted the valves following Lars paper, Tried adjusting with the motor running, even had another mechanic try, with new pushrods of course, and still bend most of the push rods. I bought the engine minus the heads and intake from a builder who had it running with some stock 350 heads. He told me that the cam was degreed 4 degrees advanced.Could this be the problem?Is it any different with the vortecs or 1.6 roller tip rockers? any help would make my life easier. Thanks, Jesse D :banghead:
Melting Slicks
Joined: Jun 2001
Posts: 2,429
Likes: 14
From: CA
Re: Keep bending push rods! Help Please! (jessed)
Two possible problems: Valve guides on Vortecs may be too tall or spring coils might be stacking
Hope this helps.
[Modified by 71coupe, 2:02 AM 4/19/2004]
Hope this helps.
[Modified by 71coupe, 2:02 AM 4/19/2004]
Le Mans Master
Joined: Apr 2003
Posts: 7,154
Likes: 1
From: I blame my Dyslexia MD
Re: Keep bending push rods! Help Please! (71coupe)
:confused: got me
they handle .48 stock, maybe something is binding
This might seem stupid, but are you sure you have the right size pushrods
MAtt
they handle .48 stock, maybe something is binding
This might seem stupid, but are you sure you have the right size pushrods
MAtt
Instructor
Joined: Apr 2002
Posts: 163
Likes: 0
From: rices landing Pa.
Re: Keep bending push rods! Help Please! (jessed)
Just a thought a friend had same problem and found out the shop had the marks on the timing gears way off, just hand turning it bent the rods
Melting Slicks
Joined: May 2001
Posts: 2,131
Likes: 4
From: May help you? You can sure as hell try!
Re: Keep bending push rods! Help Please! (jessed)
Check to make sure your valve springs aren't coil binding. Also check to see if you don't need to have your valve guides cut down a bit to accomodate the higher lift. I've heard that stock Vortechs don't work well with high lift cams without cutting the guides down. Check out Comp Cams website. They have a real good write up there that explains how to check to see if your valve train geometry is correct. If your heads or block have been decked significantly you may need shorter push rods.
If you're bending pushrods due to valve timing that means your valves are kissing the tops of your pistons i.e. you got more problems than just bent pushrods--you're gonna be replacing valves too.
If you're bending pushrods due to valve timing that means your valves are kissing the tops of your pistons i.e. you got more problems than just bent pushrods--you're gonna be replacing valves too.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Re: Keep bending push rods! Help Please! (jessed)
I'd set the timing straight up as a starting point. The 1.6 lift on the .442 cam is approx .472. My thoughts are the springs are still too short and are bottoming, the pushrods are too long for the combination or perhaps the cam isn't a .442 lift cam. Verify the pushrods are correct for the cylinder head being used. I would also verify the cam lift since it appears you bought the engine minus heads and intake.
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Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
Re: Keep bending push rods! Help Please! (LemansBlue68)
Check to make sure your valve springs aren't coil binding. Also check to see if you don't need to have your valve guides cut down a bit to accomodate the higher lift. I've heard that stock Vortechs don't work well with high lift cams without cutting the guides down. Check out Comp Cams website. They have a real good write up there that explains how to check to see if your valve train geometry is correct. If your heads or block have been decked significantly you may need shorter push rods.
If you're bending pushrods due to valve timing that means your valves are kissing the tops of your pistons i.e. you got more problems than just bent pushrods--you're gonna be replacing valves too.
If you're bending pushrods due to valve timing that means your valves are kissing the tops of your pistons i.e. you got more problems than just bent pushrods--you're gonna be replacing valves too.
Here is an article on upgrading the vortec heads for higher lift.
http://www.chevyhiperformance.com/te...ort/index.html
Melting Slicks
Joined: Jun 2001
Posts: 2,429
Likes: 14
From: CA
Re: Keep bending push rods! Help Please! (jessed)
As stated above, the guides/bosses are too tall in Vortecs for anything over .450" and must be machined down. A easy fix might be using 1.5 rockers.
Good luck
:cheers:
[Modified by 71coupe, 9:40 PM 4/19/2004]
Good luck
:cheers:
[Modified by 71coupe, 9:40 PM 4/19/2004]
Racer
Joined: Dec 2003
Posts: 304
Likes: 0
From: Pasadena Maryland
Re: Keep bending push rods! Help Please! (jessed)
I have Vortec's on my 78 with 1.5" rockers. I'm using a .460 lift cam. The stock vortecs will accomidate a .480 lift cam. I would definitely check the lift of the cam. Of course I bought everything as a kit from Pace Performance and everything was matched. Just my 2 pennies.
