Push Rod Head Design

[slo-joe55]

Reaching out to get the buick community gathering thoughts on push rod head design. I have a friend starting an engine rebuild and had a question on the push rod head design. GN v6 street build forged internals, looking to compare durability and performance. See Photo

 

[SCOOBY DOO]

I ran the stock pushrods to 6 grand all day long and never had an issue.

 

[pacecarta]

extra radiused 210 degree head is designed for clearance of the adjuster cup on high lift cams with aftermarket adjustable roller rocker arms to prevent kick out
if your standard radius tip kick out of adjuster when checked at full lift then you need the extra radius tips

 

[TIMINATOR]

Larger diameter pushrods are heavier and require more spring pressure to control, the inertia of their heavier weight contributes to the lifters collapsing along with the heavier spring pressures. Both factors negativily affect horsepower output.
TIMINATOR

 

[TIMINATOR]

Unless you run a lift over .600 you shouldn't have any need for a 210° ball end pushrod. That's why most 210° pushrods are 3/8" diameter, and .080" or .100" wall for higher lift, higher spring pressure applications.
TIMINATOR

 

[Marty Fairchild]

Reread post#2.

 

[TIMINATOR]

I've never tun stock pushrods in any of my go fast engines. With BHJ decking all blocks, milling heads for flatness, variations in HP valve lengths, machining valve seats, HP cams often having different base circles, differing geometries of roller rockers, using roller cams, and experimenting with different preload relating to horsepower production with Hydraulic lifters, I can't remember when I last used stock length pushrods. With the Buick's non adjustable valvetrain, checking pushrod length is important!
TIMINATOR

 

[slo-joe55]

Thanks guys for the input, much appreciated.

 

[slo-joe55]

Larger diameter pushrods are heavier and require more spring pressure to control, the inertia of their heavier weight contributes to the lifters collapsing along with the heavier spring pressures. Both factors negativily affect horsepower output.
TIMINATOR

Timinator which one of those rods in the photo looks bigger to you? This photo was sent to me via text.

 

[XracerX]

The one on the left is larger in diameter

 

[TIMINATOR]

True story. Both have the correct 5/16" ball ends, but the one on the left is of 3/8" diameter, swedged down to 5/16" at the ends. The 3/8" diameter pushrods also usually require the pushrod hole to be enlarged. If the pushrod pinch point in the port is ported larger, the wall there can't be ported as far due to weakening and therefore it may limit the flow and cc capacity of the port. Unless you are really turning up the RPM and spring pressure of your Buick and require a stiffer/larger diameter pushrod, there are absolutely no gains from the 3/8" diameter in your application, only negatives in cost, dead and inertial weight of the pushrod and the increased oil weight within it.
TIMINATOR

 

[slo-joe55]

XracerX, thanks.