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« Last post by Mike81K10 on May 05, 2024, 11:58:55 AM »
I checked out the 1995 Cprice 5.7L engine and the pushrods run just over 7.8 in length. I used a couple of methods now (last time today) to check for the correct pushrod lengths and both methods came up to a 7.200 pushrod length.
The last method I used to check the pushrod length was very easy and effective. I checked for the rocker geometry, which gives you the length of the pushrod. Seemed to be very accurate.
Rocker Geometry:
1) The Gross Valve Lift of Cam: .792 / 2 = .396
2) Thread Pitch on 3/8” studs = 24 TPI (.042” per turn)
3) Make 90 Degree Mark on rocker arm (Center bearing to Center roller)
4) Put a mark on top of adjuster nut so the number of turns can be counted
5) Put Rocker on the stud and measure with an Allen wrench from valve to stud the 90 degree line.
6) Figure to determine turns on adjuster nut: .396 /.042 = 9.43 (turns needed)
7) Put tape on top of adjuster nut and mark it to determine the number of turns.
Figures:
Intake Lift .495
Exhaust Lift .502
Rockers 1.6:1 (Full Roller - Scorpion Rockers)
.495 x 1.6 = .792 (Gross Lift)
.792 / 2 = .396 (Half of gross valve lift)
.396 / .042 = 9.43 (Turns needed on adjuster nut)
Afterwards: Insert and adjust pushrod checker, then removed rocker and pushrod checker. Measure pushrod checker.
Equation used to find Gross Valve Lift:
Intake Lobe Lift x Rocker Arm Ratio = Inches Gross Lift
I went ahead and ordered and the information on the pushrods from Summit Racing is below:
HDR Thickwall Chromoly Pushrods SUM-14957200
Compatible with Guideplates: Yes
Pushrod Tube Diameter: 5/16 in.
Pushrod Material: Chromoly
Top Tip Style: Ball
Bottom Tip Style: Ball
Intake Overall Length (in.): 7.200 in.
Exhaust Overall Length (in.): 7.200 in.
One-Piece Pushrod: Yes
Oiling: Yes
Tapered: No
Tip Attachment: Formed
Top Tip Diameter: 5/16 in.
Bottom Tip Diameter: 5/16 in.
Wall Thickness (in.): 0.105 in.
Heat-Treated: Yes
Quantity: Sold as a set of 16.
Notes: Commonly used with SBC O.E. hydraulic roller cams, .105 wall 210 degree ball ends.
Summit Racing™ HDR Thickwall Chromoly Pushrods
Summit Racing™ HDR premium thick-wall pushrods are a great upgrade for your engine. Factory pushrods (and even .080 wall aftermarket versions) act like a pogo stick in a running engine. Not only is static spring pressure working against them, it's also the valvetrain inertial mass increasing with RPM. This reduces power and valvetrain life. While a .080 thin-wall pushrod may not break, it doesn't mean it's the best option.
Enter the HDR's. Summit™ used FEA (Finite Element Analysis) in the initial testing. We didn't just compare them to thin-wall welded-ball factory pushrods, but with aftermarket models, as well. The results speak for themselves!
* The Summit™ HDR 5/16 x .105 wall pushrods have 20 percent less stress and 25 percent less deflection than a typical 5/16 x .080 chromoly pushrod
* The Summit™ HDR Pro LS 11/32 x .120 wall have 25 percent less stress and 28 percent less deflection than a typical 5/16 x .080 wall chromoly pushrod
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