Re: SB E-heads with large cams-Pushrod clearance issues?
[Re: Streetwize]
#954763
04/23/11 10:50 PM
04/23/11 10:50 PM
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Joined: Jan 2003
Posts: 8,547 State College, PA
RyanJ
moparts member
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moparts member
Joined: Jan 2003
Posts: 8,547
State College, PA
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Quote:
Why do SBM's run the link bars down (toward the valley) where a lot of other roller cams can run the link bars up?
Is it just because of the 59 degree angle?
Yes.
The pushrod hits the top of lifter/link bar if it is reversed in the block. a 48 degree or Big Block Mopar can get away with reversing, but not a 59 degree SB.
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Re: SB E-heads with large cams-Pushrod clearance issues?
[Re: MIKES_DUSTER]
#954765
04/24/11 10:30 AM
04/24/11 10:30 AM
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Joined: Jan 2003
Posts: 9,924 Weddington, N.C.
Streetwize
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Mike I debate this too but my gut is to go 3/8, then again there are lots of SBF that go 8500 lus with 5/16's with a lot more spring and lift than this one. 220 seat/500 open. A shorter pushrod for a given cross section is stronger too (in compression). The higher the lift the longer the pushrod length, the more extreme the arc. The Achilles heel with the SBM is the 59 degree lifter valley angle which imposes more lateral forces at the lifter side tip and (applying trig) must also slightly reduce the net lift at the valve.
One thing I do pay very close attention to is the the rocker spacing on the shafts, I use shims to keep the lateral motion between the rockers on the shafts to a minimum which in turn helps minimize a lot of pushrod oscillation. On small blocks I also like to run grooved #2 and #4 cam bearings to keep constant 360 degree oil flow to the shafts
Last edited by Streetwize; 04/24/11 10:39 AM.
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Re: SB E-heads with large cams-Pushrod clearance issues?
[Re: Streetwize]
#954767
04/25/11 08:37 PM
04/25/11 08:37 PM
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Posts: 9,924 Weddington, N.C.
Streetwize
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Just had a great talk with Terry Manton, SUPER NICE GUY.
I told him that the 3/8" might be a little tight with the shorter 6.55" length (the Morel lifter design is a bit longer than a lot of other solid rollers apparently) so he suggested I run one of his (apparently exclusive to Manton) 11/32" x .120" wall pushrod so that's what I've got coming. We had some good pushrod discussion and I know I'll definately be coming back to him again.
Last edited by Streetwize; 04/25/11 08:42 PM.
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Re: SB E-heads with large cams-Pushrod clearance issues?
[Re: MIKES_DUSTER]
#954770
04/26/11 08:22 AM
04/26/11 08:22 AM
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Posts: 9,924 Weddington, N.C.
Streetwize
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SBM guys turn a lot higher than my projected 6800 using only 5/16, Terry suggested that I try these out. My cup and ball is all 5/16 and the Comp pro-mags have lots of clearence so i should be all right. Mike remember the effect diameter has on Circumference .125 = ~.393 more perimeter wall surface, since my pushrods are only 6.55" long (due to the longer roller tappet body/ higher cup position), these pushrods should be plenty strong and still comparatively light. Terry said 48% stronger (less deflection prone)than a 5/16 but 48% weaker than 3/8
Last edited by Streetwize; 04/26/11 08:34 AM.
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Re: SB E-heads with large cams-Pushrod clearance issues?
[Re: MIKES_DUSTER]
#954772
04/26/11 09:19 AM
04/26/11 09:19 AM
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Streetwize
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Mike , I'm with you, I just want to run as big a pushrod as I felt I could fit in there and the 3/8 was a touch too tight, the 11/32 weren't all that much more, cheap insurance I felt since I'm gonna be leaning on this thing a lot.
Terry made a good point that if your pass through in the head is borderline tight but not binding it's good for the pushrod because it acts like a guideplate in that it dampens the harmonics. Both ends of a pushrod pass through a non-linear arc so the rod oscillates/flexes i think more than people realize.
Last edited by Streetwize; 04/26/11 10:21 AM.
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