What Makes Chevy's Pushrod Good?

[Shadow277]

I have heard that GM has an excellent pushrod engine. Are LS3s, 7s, etc push rods? What makes the push rod so reliable?

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[Hack]

I have heard that GM has an excellent pushrod engine. Are LS3s, 7s, etc push rods? What makes the push rod so reliable?

Low RPM can be good for reliability. The LS engines tend to be low RPM, with low horse power output for their cubic inches. Good for use in pickup trucks and station wagons.

Chevy made a lot of pushrod engines over the years, and lately their design is a lot more like a small block Ford from the 70s. Maybe that change can explain why LS engines are reliable. I assume they are a lot better than the old small block Chevys before GM started copying Ford engine design.

GM has tried to make some of the LS engines work to higher RPMs and make good power. The LS7 is an example. Those LS7 engines had a lot of problems with dropping valves. Not very reliable.

 

[Shifting_Gears]

Old tech that’s been around for a long time. Lots of opportunity for R&D. It’s a simple design, not many frills and less moving parts to fail. All Chevy pushrod motors are 2 valve per cylinder. Most modern OHC engines are 4 valves per cylinder. Pushrod = one camshaft, DOHC is 4 (for a V shaped engine).

Pushrod motors can be good low or high RPM engines, just depends on how they’re built and the application they’re being used as. Naturally, as stated, they are known for lower RPM performance and low RPM torque. OHC engines tend to need to rev to make power.

 

[Hack]

Old tech that’s been around for a long time. Lots of opportunity for R&D. It’s a simple design, not many frills and less moving parts to fail. All Chevy pushrod motors are 2 valve per cylinder. Most modern OHC engines are 4 valves per cylinder. Pushrod = one camshaft, DOHC is 4 (for a V shaped engine).

Pushrod motors can be good low or high RPM engines, just depends on how they’re built and the application they’re being used as. Naturally, as stated, they are known for lower RPM performance and low RPM torque. OHC engines tend to need to rev to make power.

I think the only reason modern pushrod engines don't make high RPM power is the limitation of having a single camshaft and what that doesn't allow to be done with variable valve timing in our modern world with emissions and fuel economy being so regulated.

The original Boss 302 engine from 1969 could rev really well and made high RPM power. GM could make pushrod engines like that, but they wouldn't get very good fuel economy and they might not pass emissions.

 

[Shifting_Gears]

I think the only reason modern pushrod engines don't make high RPM power is the limitation of having a single camshaft and what that doesn't allow to be done with variable valve timing in our modern world with emissions and fuel economy being so regulated.

The original Boss 302 engine from 1969 could rev really well and made high RPM power. GM could make pushrod engines like that, but they wouldn't get very good fuel economy and they might not pass emissions.

Agreed. Although Chevy has adapted variable valve timing on pushrod engines I would think inheritly it’s not as capable as an OHC setup.

 

[Shifting_Gears]

It's a simple motor for simple people.

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