Do I need longer pushrods?
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Melting Slicks
Joined: Sep 2000
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From: Green Bay WI
Do I need longer pushrods?
Please help a newbie engine builder here... In the pic, the rocker makes contact with the spring cap - does this mean I need longer pushrods? Thanks! :)
Race Director
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From: The Top of Utah
Re: Do I need longer pushrods? (cprgmr)
A longer push rod will give you clearance where you've circled. But it isn't all that simple. How is your rocker roller to valve stem contact? The rocker arm geometry is most important. That is the contact area of the rocker on the valve stem, through it's cycle. If the geometry needs a longer push rod, you may be able to kill two birds with one stone. Otherwise you may go from the frying pan into the fire. Are those rockers supposed to fit with your diameter valve springs?
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Melting Slicks
Joined: Mar 1999
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From: Rochester NY
Re: Do I need longer pushrods? (CFI-EFI)
Your rockers contact the retainer. It not big deal, all you have to do is to grind the rock around 45* to get it to clear. Agostino Racing Engine built my 383LT1 and I have the same problem there. They ground a 45* angle to clear the retainer(spring) I am using Crane Gold Roller Rockers.
Bruce
Bruce
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Melting Slicks
Joined: Sep 2000
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From: Green Bay WI
Re: Do I need longer pushrods? (CFI-EFI)
How is your rocker roller to valve stem contact? The rocker arm geometry is most important. That is the contact area of the rocker on the valve stem, through it's cycle.
Cylinder #5
Cylinder #7
Are those rockers supposed to fit with your diameter valve springs?
Race Director
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From: The Top of Utah
Re: Do I need longer pushrods? (cprgmr)
You know, that was an excellent question. I went back out to the garage and took these pics of cylinder #5 & #7. The roller tip is off from the center of the valve stem!
Number 5 looks particularly bad. It is harder to tell on #7, because of the angle of the pic. What really counts is the path of travel through the cycle. From how it looks from here, I think push rods may solve both problems.
A better source of compatibility would be the rocker mfgr. I don't know how specific you got with the head guy, but mast rocker suppliers have a myriad of part numbers for varying applications.
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Race Director
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From: Vancouver,Wa.
Re: Do I need longer pushrods? (cprgmr)
Yes you need longer push rods. And I would have some one that is qualified set them up. Looks like one of your guide plates is a little off to.
[Modified by Corvette0096, 6:21 PM 4/3/2004]
[Modified by Corvette0096, 6:21 PM 4/3/2004]
Thread Starter
Melting Slicks
Joined: Sep 2000
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From: Green Bay WI
Re: Do I need longer pushrods? (Corvette0096)
Yes you need longer push rods. And I would have some one that is qualified set them up. Looks like one of your guide plates is a little off to.
[Modified by Corvette0096, 6:21 PM 4/3/2004]
[Modified by Corvette0096, 6:21 PM 4/3/2004]
Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Re: Do I need longer pushrods? (cprgmr)
I would replace those rockers, if necessary, before grinding them. Grinding will weaken the tip and could lead to early failure...potentially far more expensive than a new set of RRs.
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Racer
Joined: Mar 2004
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From: Oakley Ca
Re: Do I need longer pushrods? (65Z01)
Looks to me like longer push rods will help in both depts. With a felt marker darken the end of the valve stem and turn the engine over a few times with the rocker in place and correctly adjusted. remove the rocker and look at the witness mark left on the valve stem. It should be near the center of the stem. By the way are your rockers correctly adjusted? You can run em down too far and get the contact you are experiencing.
Race Director
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From: Vancouver,Wa.
Re: Do I need longer pushrods? (olman)
Looks to me like longer push rods will help in both depts. With a felt marker darken the end of the valve stem and turn the engine over a few times with the rocker in place and correctly adjusted. remove the rocker and look at the witness mark left on the valve stem. It should be near the center of the stem. By the way are your rockers correctly adjusted? You can run em down too far and get the contact you are experiencing.
Bingo..
Le Mans Master
Joined: Feb 2000
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From: Kempner Texas
Re: Do I need longer pushrods? (olman)
An inexpensive pushrod length checking tool from Mr. Gasket or Moroso will let you determine the length you need.
You can loosen the rocker studs and move the guide plates (I'm assuming you have guide plates) to better center the roller tip of the rocker on the valve stem.
Pushrods usually come in .050 increments, so getting one that EXACTLY meets yours needs is a shot in the dark.
If the EXACT length you need isn't "off-the-shelf", remember, it's always better to choose a pushrod that is a little too long rather than ones that are a little too short.
Grinding the underside of the rockers isn't a big deal. I use to have to do this when using Crane Gold roller rockers on BB Chevys that has 1.625 diameter springs. Never had a failure after the grinding. You'll need at least .030 clearance between the rocker and the retainer throughout the entire rocker cycle.
Jake
[Modified by JAKE, 8:38 PM 4/4/2004]
You can loosen the rocker studs and move the guide plates (I'm assuming you have guide plates) to better center the roller tip of the rocker on the valve stem.
Pushrods usually come in .050 increments, so getting one that EXACTLY meets yours needs is a shot in the dark.
If the EXACT length you need isn't "off-the-shelf", remember, it's always better to choose a pushrod that is a little too long rather than ones that are a little too short.
Grinding the underside of the rockers isn't a big deal. I use to have to do this when using Crane Gold roller rockers on BB Chevys that has 1.625 diameter springs. Never had a failure after the grinding. You'll need at least .030 clearance between the rocker and the retainer throughout the entire rocker cycle.
Jake
[Modified by JAKE, 8:38 PM 4/4/2004]
Drifting
Joined: Oct 1999
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From: Gloucester Va
Re: Do I need longer pushrods? (JAKE)
This is something I've been trying to figure out. If I need longer pushrods? Question I have is what does a longer pushrod do? I used the stock length in my car but again have wondered if I need longer, but don't under stand what effect it has. :confused:
Thread Starter
Melting Slicks
Joined: Sep 2000
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From: Green Bay WI
Re: Do I need longer pushrods? (88_vette)
This is something I've been trying to figure out. If I need longer pushrods? Question I have is what does a longer pushrod do? I used the stock length in my car but again have wondered if I need longer, but don't under stand what effect it has. :confused:
However, I've been eye-balling the rocker tip on the valve stem and it looks to be right in the middle (which would indicate the proper pushrod length).
Race Director
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From: The Top of Utah
Re: Do I need longer pushrods? (cprgmr)
However, I've been eye-balling the rocker tip on the valve stem and it looks to be right in the middle (which would indicate the proper pushrod length).
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Le Mans Master
Joined: Mar 2002
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From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Re: Do I need longer pushrods? (cprgmr)
However, I've been eye-balling the rocker tip on the valve stem and it looks to be right in the middle (which would indicate the proper pushrod length).
Thread Starter
Melting Slicks
Joined: Sep 2000
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From: Green Bay WI
Re: Do I need longer pushrods? (olman)
Looks to me like longer push rods will help in both depts. With a felt marker darken the end of the valve stem and turn the engine over a few times with the rocker in place and correctly adjusted. remove the rocker and look at the witness mark left on the valve stem. It should be near the center of the stem. By the way are your rockers correctly adjusted? You can run em down too far and get the contact you are experiencing.
Le Mans Master
Joined: Mar 2002
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From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Re: Do I need longer pushrods? (cprgmr)
Don't move it side to side, spin a couple revolutions to get the sweep I mentioned earlier. You should have a pattern about an eighth inch or so wide. How's the clearance on the retainer?
Edit: it looks close, but I think I'd like to see the closed mark start a little more inboard........maybe.......... Do the revolution thing.
[Modified by Caboboy, 10:10 AM 4/4/2004]
Edit: it looks close, but I think I'd like to see the closed mark start a little more inboard........maybe.......... Do the revolution thing.
[Modified by Caboboy, 10:10 AM 4/4/2004]
Advanced
Joined: Mar 2004
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From: Elk Grove Ca
Re: Do I need longer pushrods? (cprgmr)
Before you start going to longer pushrods, I'd check the roller to valve contact. Ideally you want the roller to contact the middle of the valve stem at full open sweeping from the lower part of center to the center of the valve stem. Longer pushrods will change that angle and contact area.
I don't know but from the picture, it doesn't appear to be making actual contact. Very close, but not actual contact?? I wouldn't recommend grinding the arm to get your clearance but I've done it before with no ill effects, and I only take VERY little off. and then buff it clean afterwards.
Good luck
I don't know but from the picture, it doesn't appear to be making actual contact. Very close, but not actual contact?? I wouldn't recommend grinding the arm to get your clearance but I've done it before with no ill effects, and I only take VERY little off. and then buff it clean afterwards.
Good luck
Thread Starter
Melting Slicks
Joined: Sep 2000
Posts: 2,710
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From: Green Bay WI
Re: Do I need longer pushrods? (Caboboy)
Don't move it side to side, spin a couple revolutions to get the sweep I mentioned earlier. You should have a pattern about an eighth inch or so wide. How's the clearance on the retainer?
Edit: it looks close, but I think I'd like to see the closed mark start a little more inboard........maybe.......... Do the revolution thing.
[Modified by Caboboy, 10:00 AM 4/4/2004]
Edit: it looks close, but I think I'd like to see the closed mark start a little more inboard........maybe.......... Do the revolution thing.
[Modified by Caboboy, 10:00 AM 4/4/2004]
Here are the pics...
