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Pushrod question?
#453726
08/29/09 08:30 PM
08/29/09 08:30 PM
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Joined: Aug 2005
Posts: 761
KY
juicedcuda
OP
super stock
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OP
super stock
Joined: Aug 2005
Posts: 761
KY
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Do you think manton or smith bros can make a 5/16 pushrod that would be equally as strong as a 3/8? I am running a pretty stout solid roller.
1970 Plymouth 'Cuda
1970 Plum Crazy "Gold Duster"
1973 Gold Duster
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Re: Pushrod question?
[Re: juicedcuda]
#453727
08/29/09 08:39 PM
08/29/09 08:39 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Do you think manton or smith bros can make a 5/16 pushrod that would be equally as strong as a 3/8? I am running a pretty stout solid roller.
I'm pretty sure they can but the wall thickness would
make them pretty heavy.... its alot easier to pick
up the strength in the diameter
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Re: Pushrod question?
[Re: MR_P_BODY]
#453728
08/29/09 08:46 PM
08/29/09 08:46 PM
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Joined: Aug 2005
Posts: 761
KY
juicedcuda
OP
super stock
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OP
super stock
Joined: Aug 2005
Posts: 761
KY
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Yeah but I have already clearanced the heads as much as I am comfortable with and I am still afraid that a 3/8 would lay on the head and not sit in the rocker cup all the way.
1970 Plymouth 'Cuda
1970 Plum Crazy "Gold Duster"
1973 Gold Duster
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Re: Pushrod question?
[Re: juicedcuda]
#453729
08/29/09 08:56 PM
08/29/09 08:56 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Yeah but I have already clearanced the heads as much as I am comfortable with and I am still afraid that a 3/8 would lay on the head and not sit in the rocker cup all the way.
If you dont have any 3/8 push rods that are the right
length to test with.... get a piece of 3/8" threaded
rod and cut it to length and hit the ends on a grinder
so they sit in the cup and lifter and check it... its
a cheap way to check... just use a light test spring
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Re: Pushrod question?
[Re: MR_P_BODY]
#453730
08/29/09 09:17 PM
08/29/09 09:17 PM
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Joined: Apr 2007
Posts: 871
WA 98043
thecarfarmer
super stock
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super stock
Joined: Apr 2007
Posts: 871
WA 98043
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If you do find you need to run 5/16 pushrods, Smith Brothers makes 'em.
I'm running 8.35" X .115 wall in a solid roller application (540# pressure over the nose of the cam) in a B engine.
They've been first-class guys to deal with.
I'm running offset rockers (too good a price to pass up) on Stealth heads, hence the small pushrod.
BTW, I'd run 3/8" if there were room...
-Bill
Seduce the attractive, and charm the rest.
******
489 C.I.D., roller cam, aftermarket heads, tunnel ram, stock '54 Dodge rear axle assembly: which of these doesn't belong?
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Re: Pushrod question?
[Re: juicedcuda]
#453731
08/30/09 11:41 AM
08/30/09 11:41 AM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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In practical terms, it's impossible.
Almost all of the column stiffness of a pushrod is a function of its diameter (not wall thickness), and even a solid 5/16" bar is weaker than a 3/8" OD pushrod with only 1/32" wall. Compared to a common 3/8" .083" wall, it's 53% as stiff.
Boffin Emeritus
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Re: Pushrod question?
[Re: juicedcuda]
#453732
08/30/09 12:03 PM
08/30/09 12:03 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
Do you think manton or smith bros can make a 5/16 pushrod that would be equally as strong as a 3/8? I am running a pretty stout solid roller.
how "stout" are the springs for that roller and what is the approximate length?
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Re: Pushrod question?
[Re: juicedcuda]
#453734
08/30/09 01:45 PM
08/30/09 01:45 PM
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Joined: Apr 2007
Posts: 871
WA 98043
thecarfarmer
super stock
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super stock
Joined: Apr 2007
Posts: 871
WA 98043
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Well, your open pressure is about a hundred pounds over the pushrods are about an inch longsr. Don't know if what I'm getting away with will work for your setup or not. But, the guys who make the parts can tell you: pushrods.net or (800) 367-1533 If anybody'd know, I'd bet they would. -Bill
Seduce the attractive, and charm the rest.
******
489 C.I.D., roller cam, aftermarket heads, tunnel ram, stock '54 Dodge rear axle assembly: which of these doesn't belong?
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Re: Pushrod question?
[Re: polyspheric]
#453735
08/30/09 04:29 PM
08/30/09 04:29 PM
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Joined: Aug 2004
Posts: 2,128
sweden
sshemi
top fuel
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top fuel
Joined: Aug 2004
Posts: 2,128
sweden
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Quote:
In practical terms, it's impossible.
Almost all of the column stiffness of a pushrod is a function of its diameter (not wall thickness), and even a solid 5/16" bar is weaker than a 3/8" OD pushrod with only 1/32" wall. Compared to a common 3/8" .083" wall, it's 53% as stiff.
And a 5/16 solid is weaker than a 5/16 tube.
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Re: Pushrod question?
[Re: sshemi]
#453736
08/30/09 06:31 PM
08/30/09 06:31 PM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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And a 5/16 solid is weaker than a 5/16 tube.
Widely repeated, but wrong.
Removing metal does not increase stiffness, it increases stiffness per pound, or stiffness per square inch of load.
Boffin Emeritus
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Re: Pushrod question?
[Re: juicedcuda]
#453737
08/30/09 11:08 PM
08/30/09 11:08 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
Quote:
Quote:
Do you think manton or smith bros can make a 5/16 pushrod that would be equally as strong as a 3/8? I am running a pretty stout solid roller.
how "stout" are the springs for that roller and what is the approximate length?
The approximate length is 9 5/8" long. The springs are Comp, here are the specs:
Dual Valve Springs I.D. of Outer Dia.: 1.125"
# I.D. of Inner Dia.: .719"
# Seat load: 228lbs @2.050''
# Open load: 636lbs @1.300''
# Coil bind: 1.192''
# Rate: 544lbs/in
# With damper.
you should be able to get 5/16 pushrods that will handle that with no problem. 
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