Re: Bending push rods BB engine with hydraulic roller cam
[Re: rth]
#668910
04/15/10 11:34 AM
04/15/10 11:34 AM
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Joined: Nov 2006
Posts: 75 Illinois
ChrisDavis
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Come on. Someone must be able to explain this to me?
My new Scorpions just arrived. I get to put things back together this weekend. I can hardly wait.
I have another question. What torque do you tighten the rocker shaft hold down bolts to with Edelbrock aluminum heads? The shaft hold down kits appear to be Mopar Performance and I believe they are using grade 8 bolts. When I took them off they were at maybe 80 Ft. Lbs. It was about all I could do to break them loose with a socket wrench.
Last edited by ChrisDavis; 04/15/10 11:43 AM.
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Re: Bending push rods BB engine with hydraulic roller cam
[Re: ChrisDavis]
#668911
04/15/10 12:03 PM
04/15/10 12:03 PM
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Joined: Feb 2003
Posts: 12,675 Columbia, CT
moper
I Live Here
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I Live Here
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Posts: 12,675
Columbia, CT
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The valvetrain is complicated.. and it's similar to balancing the rotating assembly in that it has to deal with harmonics that are a natural part of it's operation. Bent pushrods can be from a bunch of things. Some possibilities: Mechanical contact... retainers to rocker, pushrod to head/gasket/guideplate, valve to piston, coil bind on the springs, loss of lifter plunger motion, guides too tight. Deflection of the pushrod itself. Harmonic issues from wrong springs, pushrod angles, rpm, or poor geometry. So there's no "it's always 'x'" here. If you are not sure, I would have someone who is sharp look at what you have, or post a bunch of pics of things like the threads left showing on the adjuster, the sweep pattern of a few cylinders, a side close up view of the rocker with the lifter on the cam base circle... On the Edelbrock heads... They use a helicoil in the rocker support, but you want to make sure the bolts thread completely through it. I've found factory bolts are usually too short, so I replace them with simple grade 8s of the same diameter that are 3/8" longer. IIRC the rocker shaft torque spec is 20ftlbs. It's not too much.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Bending push rods BB engine with hydraulic roller cam
[Re: Dodgem]
#668913
04/15/10 12:20 PM
04/15/10 12:20 PM
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Joined: Nov 2006
Posts: 75 Illinois
ChrisDavis
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Thanks for the responses.
I was mainly wondering about some others here mentioning that floating the lifters will bend push rods. I don’t see how that could happen without the valve hitting the piston and if the valve hits the piston I would think there would be other more serious damage.
My cam is about .550 lift and 230 X 236 @.050. I have checked coil bind and I have anywhere from .050 to .080 remaining. I ordered Manton custom length push rods and the pattern on the tip of the valve is good. That also leaves about 3 threads of the rocker stud exposed below the rocker arm. It all looks good.
I plan on pushing the envelope for RPM and wanted to know the dangers of hitting the edge of valve float. Obviously I won’t be holding it at that RPM, but the valves will probably be floating a little bit before I am able to sense it.
Last edited by ChrisDavis; 04/15/10 02:28 PM.
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Re: Bending push rods BB engine with hydraulic roller cam
[Re: Mr.Yuck]
#668916
04/15/10 01:00 PM
04/15/10 01:00 PM
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Joined: Jan 2003
Posts: 17,875 S.E. Michigan
ZIPPY
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I Live Here
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S.E. Michigan
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262 @ .050, .630 gross lift solid roller, 451CI and E heads here. Makes max HP at 6300 rpm, has seen 6800 on chassis dyno and though it will go that high, the power falls off. I have the rev limiter at 7 grand and try to never hit it.
I'm not trying to be mean or mess up your thread, but honestly 6500 or 7 grand with a 230 degree camshaft is really not going to do anything...
Rich H.
Esse Quam Videri
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Re: Bending push rods BB engine with hydraulic roller cam
[Re: ChrisDavis]
#668917
04/15/10 01:11 PM
04/15/10 01:11 PM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
I plan on a couple of 6500 RPM blasts. Right now I hit a brick wall at 6K. However it is pulling real hard when the brink wall shows up. The springs are the stock Edelbrock ones that came with the heads. I had them checked and they were very close to what the cam card called for. I think it was about 130 on seat and maybe 320 open.
I'm using a Scott Brown 540-548 solid w/ 1.5 rollers, He pretty much told me that it likes to be shifted at 5200 for the 1-2 and 5600 for the 2-3. 6500 seems like overkill to me.
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Re: Bending push rods BB engine with hydraulic roller cam
[Re: ChrisDavis]
#668922
04/15/10 03:16 PM
04/15/10 03:16 PM
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Joined: Dec 2007
Posts: 7,759 So Cal
HealthServices
Why would you even post that?
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Why would you even post that?
Joined: Dec 2007
Posts: 7,759
So Cal
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If I remember right each time you float a valve you damage the springs enough that over time, the valves will float at a lower and lower RPM
Allen
Here's a novel idea, let's not throw a bunch of parts at the car hoping it will fix the problem and instead spend a little time diagnosing it first.
Life was a little easier when I was just a wrench.
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Re: Bending push rods BB engine with hydraulic roller cam
[Re: HealthServices]
#668923
04/15/10 06:31 PM
04/15/10 06:31 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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"valve float" is really a misnomer. It's more like lifter jump. When the lifter leaves the lobe of the cam and there is clearance is what we usually call valve float. several issues can cause it, weak springs, weak pushrods, heavy lifter, too much rpm are the primary causes.
That all being said, you're running a heavy lifter at high rpms, not sure what pushrods you are using (are they thick wall ones?) and the valve springs on the Edelbrock head may not be up to controlling the valve train at the higher rpms you want to run. Hydraulic roller lifters generally call for a different spring spec than a similarly spec's hydraulic flat tappet cam (aggressive lobes tend to require stouter spring and aftermarket roller cams usually have more aggressive ramp profiles).
Good luck
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Bending push rods BB engine with hydraulic roller cam
[Re: stumpy]
#668927
04/16/10 06:10 PM
04/16/10 06:10 PM
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Joined: Nov 2006
Posts: 75 Illinois
ChrisDavis
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On a day to day basis I plan on shifting at 6K. Right now I have a slight miss through the RPM's as well. Also to shift at 6K means hitting float right at the shift point. I don't want to go too far on the miss subject here since I already have a thread going on it at: 451 High RPM Miss
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