Hypothetical question:

X motor,
with proper X valvespring,
with, say .080 wall pushrods,
With ti retainers.


Then:
change pushrods in above motor to .140 wall pushrods, steel retainers. Nothing else.



Does the motor use the same spring with the two changes? Do the pro builders weigh componets or do they simply guess?

Weight on the valve side of the valve train has more effect than the tappet side. Spintron would be the sure way. For what it's worth I run 2.25 stainless in my -1 head. T&D paired rockers, Comp 892 tappets. Pushrods are 7/16" tapered .165" wall. I found a broken spring at Monster Mopar. It shattered the outer into 4 piieces. The car had a semi-final and win 2 weeks before, ran perfect. It had a semi-final and win at MM. When I got home I pulled all the springs. One more broken outer, 6 broken inners. The final pass at MM was 146.9. Best ever has been 147.7. Car never skipped a beat.
Doug

It all adds up. Reducing the weight with these components is essentially the same as adding more spring, however more spring reduces mechanical efficiency. Hence the advancement with technology in valve train materials.

Pushrods.....got to be careful there.....spintrons have identified some crazy actions with those. Increasing wall thickness alone is generally not the answer.

Comp Cams seemed to hint a year or so ago that the benefits of stiffer pushrods outweighed there extra mass.

In my book, pushrods are a classic example of unconstrained bending in a long narrow column. The largest effect on stiffening the pushrod is by increasing diameter, increases stiffness by the increase cubed, IIRC. Unfortunately there seem to be many instances where pushrod diameter has to be compromised for clearance.

R.

The heavy wall pushrod may see less flexing and miniscule power increases,the steel retainer if the same demisions as the titanium will work with the current springs.The weight of the changed componants would negate any power advantages.The power increase in these componants usually comes from their strength and light weight usually freeing up more RPM and decreasing harmonics.

I had a pair of Smith Bros. pushrods fail(one broke in half in the middle after bending and took the other one out bending it also) on a dyno test, it hurt the cam lobe and broke the top of the Crower solid roller lifter off I had ordered 3/8 diameter with .120 wall for a roller cam originally, I took the broken one back to Smith Bros and one of the shop employees made a comment that thier .083 wall 3/8 pushrods shoouldn't of failed that way They where not .120 wall like I had ask and paid for They replaced the two pushrods for no charge but didn't offer to help pay for the cam repair and lifters damaged. Smith Bros. was 5 miles awy from me back then, they have since moved thier shop 23 miles away now to Redmond OR. I fixed the motor and ordered a set of Manton Series # 3/8 diameter .120 wall thick pushrods of the exact same length and took them with me to the dyno, we made several pulls to warm the motor up with the Smith Bros. pushrods in it, changed the oil and filter. I checked the valve clearances and made several more pulls to make sure the motor was repeating. I changed the pushrods, no other changes, and that motor picked up 300 RPM to peak HP and 8 HP on that change Stiffer is better on pushrods when there are any doubts Years ago, circa 1968 or 1969, Don Prudhome(SP?) tested a set of tapered D&D pushrods in his old front engine top fuel dragster at Orange county dragstrip one Wednesady night, the motor picked up around 800 RPM and he had to lean the fuel system down around 20% was what was listed in the article that Hot Rod or Car Craft put out later about that test. The car picked up quite a bit also from that change, I don't remeber the exact amount but I'm thinking around .2+ ET and 2 to 3 MPH The RPM you shift at has a lot to do with what will work best for you also

Trend is toward stiffer pushrods ignoring weight there--I use titanium retainers on everything I can--over the years it has proven to be the easiest way to get better spring life, better rpm and more protection against loss of control--never race without them. On the dyno you find out pretty quick that engines love more spring pressure thus better control---big solids like the beloved .590 and Comp .650 always run better with more spring.
My Nascar pal tells me they turn 10K rpm now but the valvetrain is so very light they do it with 125 seat and 300 plus open so...weight is everything!
They are going roller next season so...I expect RPMs to climb up and up--I bet 11,000 is going to be the slow pokes and some will turn more--has to happen--it is the only logical place to find more HP.
Mopars have always had the heavy valves--11/32 " in all the aftermarket heads helps a lot but then when you get Indy and Hemi size heads it is still trouble--the best running race stuff alwyas has titanium valves--you can Hear the diff on the dyno--every time!!!
Average racer should not load the car on the trailer without titanium retainers in my book.
Taller springs, bigger diameter are always better.
Better control, better life, more RPM every time.
I have never been able to see a loss from mechanical --like more pressure etc---the gains from better control always trump the mechanical myth in my experience.

Look at what nascar runs for pushrods and that with tell you. I run 1/2 inch .165 wall pushrods in my motor.

What do people think of the tapered pushrods? Does the triangle shape actually improve stiffness in the pushrods? I am thinking of long ones like in a Hemi....Tim

The single tapered are the hot shizten Plus you can shoot some pool with them(the Hemi ones anyways) I had heard recently of some of the hot SB Ford racers using 9/16 pushrods, them babys are real short