Upgraded pushrods?
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Launching!
Joined: Apr 2021
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From: New Athens IL
Upgraded pushrods? What are your thoughts on larger diameter pushrods? Ive always run just a .080 wall 5/16 pushrod. At what point do you step up to a larger diameter? Im be using btr 660 spring and hollow intake valves w/ ti retainers. Valve train is pretty light. This might be a 7200 to 7400 rpm limit.
I had Smith Brothers make some .115 wall 5/16 pushrods for my latest build which is a 370 with L92 heads with Ferrea valves and PAC .660 lift springs. Camshaft in that build is a 238/246 .633 I & E on a 111+3 LSA. I would imagine those are lighter than the larger 11/32 and stiffer than your average 5/16 pushrod.
Last edited by 01CamaroSSTx; Mar 26, 2026 at 07:49 PM.
Diameter trumps wall thickness, from a strength perspective. You should have no problem running 11/32 rods. I’ve put them in a lot of OEM headed builds. Always mock up a larger rod and turn the engine a couple revolutions, to ensure it clears the heads. The pushrod is referred to the second spring in the valvetrain. Pushrods flex a lot more than most realize and the flex creates harmful harmonics as well as robbing you of actual valve lift. When possible, always go with the largest diameter pushrod possible, if you’re looking to gain performance.
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I ordered brodix br1 heads from mueller and also ordered my pushrods though him and he suggested manton .118 wall 5/16 pushrods, he said they’re very strong and should be no problem with my set up which is a 1800hp dart 388”. Heads have his severe duty stainless intake valves and inconel exhaust valves with BTR .685 springs.
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Thread Starter
Launching!
Joined: Apr 2021
Posts: 245
Likes: 108
From: New Athens IL
I ordered brodix br1 heads from mueller and also ordered my pushrods though him and he suggested manton .118 wall 5/16 pushrods, he said they’re very strong and should be no problem with my set up which is a 1800hp dart 388”. Heads have his severe duty stainless intake valves and inconel exhaust valves with BTR .685 springs.
Agree, but if he can fit a 3/8 .080 Manton then that's the winner. @TurboBuick6 only works for PAC and sees valvetrain everyday...The man knows a lot, Che70velle, as well. Take the advice.
Thread Starter
Launching!
Joined: Apr 2021
Posts: 245
Likes: 108
From: New Athens IL
I would imagine the new BTR heads are able to run a 3/8” pushrod. If that’s the case I would run the 3/8” series 3 Manton. I have a very low mile set at 7.940” long that serve me no use anymore. If you’re interested and they fit your needs for measurements let me know and you can have them for cheap.
It might not seem like that much of a length increase, from an LS OEM length of 7.45” going to an 8” pushrod, but in the grand scheme of pushrods, and the job they do, it’s a lot. A whole lot. I would never install an 8” pushrod with a diameter under 3/8”. The longer the rod, the more deflection it will have. I can’t say it enough…the pushrod is the second spring in the valvetrain. They deflect a LOT more than you’d like to believe. Wall thickness helps with overall strength to a degree, yes, but overall rod diameter is what determines the strength of the rod. A pushrod in a V8 engine doesn’t move up and down in a straight line. It changes angle slightly north and south twice with every lifter movement. This angle change puts the whipping action into effect, on the pushrod. Always run the largest diameter rod you can fit in the application your building.
Thread Starter
Launching!
Joined: Apr 2021
Posts: 245
Likes: 108
From: New Athens IL
It might not seem like that much of a length increase, from an LS OEM length of 7.45” going to an 8” pushrod, but in the grand scheme of pushrods, and the job they do, it’s a lot. A whole lot. I would never install an 8” pushrod with a diameter under 3/8”. The longer the rod, the more deflection it will have. I can’t say it enough…the pushrod is the second spring in the valvetrain. They deflect a LOT more than you’d like to believe. Wall thickness helps with overall strength to a degree, yes, but overall rod diameter is what determines the strength of the rod. A pushrod in a V8 engine doesn’t move up and down in a straight line. It changes angle slightly north and south twice with every lifter movement. This angle change puts the whipping action into effect, on the pushrod. Always run the largest diameter rod you can fit in the application your building.
It might not seem like that much of a length increase, from an LS OEM length of 7.45” going to an 8” pushrod, but in the grand scheme of pushrods, and the job they do, it’s a lot. A whole lot. I would never install an 8” pushrod with a diameter under 3/8”. The longer the rod, the more deflection it will have. I can’t say it enough…the pushrod is the second spring in the valvetrain. They deflect a LOT more than you’d like to believe. Wall thickness helps with overall strength to a degree, yes, but overall rod diameter is what determines the strength of the rod. A pushrod in a V8 engine doesn’t move up and down in a straight line. It changes angle slightly north and south twice with every lifter movement. This angle change puts the whipping action into effect, on the pushrod. Always run the largest diameter rod you can fit in the application your building.
If trying to picture what Scott is saying, look at a pole vaulter. The pole flexes after the vaulter plants it, and on his way up the stored energy is released, and suddenly straightens out the pole, vaulting him up and over the crossbar. Every PR flexes. Even a 1/2" diameter with 3/16" wall thickness. Smaller diameter and thinner wall exacerbates the problem. Example: When the PR flexes, then straightens out, it could launch the valve open farther than the actual lobe can. I know some guys around here running on dirt in circle track races that are limited on the valve lift they can run. They actually want to launch the valve (planned valve float to circumvent the low lift rules) and claim they make more power than without doing this. However, these are SBC powered, dedicated oval dirt track race cars that prioritize speed over reliability. Plus lift is class limited to....I wanna say .450@the valve, and probably at 5,500-6,000 rpm. But I know they actually do this. Seems like it would tear Hell out of the valvetrain. But, again, they probably go thru cams, lifters, and springs every 3 months(?). Not good for our LS motors, just trying to further add to what Scott is saying.....
