Engine build and pushrods

Krause · Nov 15, 2014

Hey Guys,
I apologize in advance, this may be a dumb question I just have missed the boat on at some point...
Building a mild 7.3 this winter. Will be 160/80's from rosewood, one of the HPOP's available, a T4 kit with a billet 366. (Have the other supporting mods, efuel, intercooler, etc etc..)

My question comes with pushrods. The remainder of that equation ^ seems to be the tried and true valvesprings, headstuds, and pushrods. Why are pushrods necessary?
I was speaking with another member and friend, and we discussed how if something was going to go wrong, I (we) would rather have a bent pushrod than a broken valvestem. One is an easy fix, the other is a head removal and potentially much more. If there is going to be a week link, why not leave it as the pushrods and know what you are getting into?

Also, what is the actual performance advantage of having smithbros pushrods that are 5x stronger? They are not lighter are they?

Just trying to understand this guys, thanks in advance.
-Krause

MossBack · Nov 15, 2014

When you up the seat pressure from 70 to well over 130 I the valve using the same "stock" pushrods they would easily bend at that psi. When I decided to run 910's shimmed to 130 keeping weak pushrods seemed like pissing in the wind. Just my .02

JD3020 · Nov 15, 2014

I've been running shimmed 910's with stock pushrods for a while, and i've never bent one. Reason i kept my stockers is they cost nothing vs $200+ for new ones. If something were to ever happen and allow P/V contact in theory i should just bend a pushrod, vs breaking a rocker or bending a valve. Also i think it helps keep the rockers alive with high spring pressures, stockers are probably flexing a little bit instead of putting 100% of the force into the stock rockers which are known to break.

Knock on wood, i have yet to have a valvetrain issue and this is an engine that sees high rpm's very very often. It sees 4k+ often when i'm playing around.

MossBack · Nov 15, 2014

JD3020 said:
I've been running shimmed 910's with stock pushrods for a while, and i've never bent one. Reason i kept my stockers is they cost nothing vs $200+ for new ones. If something were to ever happen and allow P/V contact in theory i should just bend a pushrod, vs breaking a rocker or bending a valve. Also i think it helps keep the rockers alive with high spring pressures, stockers are probably flexing a little bit instead of putting 100% of the force into the stock rockers which are known to break.

Knock on wood, i have yet to have a valvetrain issue and this is an engine that sees high rpm's very very often. It sees 4k+ often when i'm playing around.

This logic makes sense to me as well... I did the pushrods since I had a extra week to wait on my injectors for sending cores first... Next week I am installing swamps stage 2 beehive springs and pushrods as well as H11'so that should be fun

Krause · Nov 15, 2014

Krause said:
I was speaking with another member and friend, and we discussed how if something was going to go wrong, I (we) would rather have a bent pushrod than a broken valvestem. One is an easy fix, the other is a head removal and potentially much more. If there is going to be a week link, why not leave it as the pushrods and know what you are getting into?

-Krause

JD3020 said:
I've been running shimmed 910's with stock pushrods for a while, and i've never bent one. Reason i kept my stockers is they cost nothing vs $200+ for new ones. If something were to ever happen and allow P/V contact in theory i should just bend a pushrod, vs breaking a rocker or bending a valve. Also i think it helps keep the rockers alive with high spring pressures, stockers are probably flexing a little bit instead of putting 100% of the force into the stock rockers which are known to break.

Knock on wood, i have yet to have a valvetrain issue and this is an engine that sees high rpm's very very often. It sees 4k+ often when i'm playing around.

MossBack said:
This logic makes sense to me as well... I did the pushrods since I had a extra week to wait on my injectors for sending cores first... Next week I am installing swamps stage 2 beehive springs and pushrods as well as H11'so that should be fun

That was what I was getting at. I would rather have the pushrods as almost an engineered week point to protect other components which are way more difficult to change.
That said, if they cant open a valve without bending, then thats another story.

Swaan · Nov 15, 2014

I've been running with 910s springs and stock push rods for a while now. 175/80 inj and high boost over 40 psi regularly. Ussally run up to the governor on wot runs. No problems here.