Push rod question

Hi guys
Is it ok to run a tapered pushrod fat side up?
Thanks for looking

Yes you can run the fat side up, I’m just trying to figure out why. The upper side is usually the right spot, but if they fit, orientation doesn’t matter.

I'm going to assume your using ball and ball type pushrods, correct? If so are both ends the same size ball? If not you should run the balls in the proper size seats in the rocker arm and lifters If their the same size5/16x 51/5 ball on both ends or 3/8 ball on both ends then it doesn't really matter other than having the heavy end of the pushrod near the rocker arm instead of on the lifter seat
I put the thicker end of the pushrod in the lifter seat normally on single tapered pushrods with both ball and cup or ball and ball pushrods

My tight spot is the block deck line. With the the rod in fat side up I have more clearance that fat side down. Still close but acceptable.
Thanks

5/16 ball both ends.

That was my concern heavy end up , but I think I am overthinking it
G

I would put the stronger thick part down as long as it clears the block at all lift points
My thinking is the weakest point is the narrowest point on the shaft, I think the pushrod is angled more at the liter than it is near the rocker arm adjuster

Didn’t take any measurements the other night but at a glance fat side down was closer I”ll check over the weekend.
My tight spot is at the block at the deck when on the base of the cam lobe. Once it starts lift it moves away quickly . This pr is intake and offset , 7/16 to 3/8 taper, And just over 10” so trying to not go down in thickness. Could grind the block some but was hoping not to .
Thanks for the help, G

this is a quote from Manton Pushrods.

"Do not allow over clearancing for the pushrod. This may cause the pushrod to move around or deflect more than needed. Clearance of .010 at the closest point, wherever that may be during its complete cycle is sufficient. The cylinder head and engine block can often be utilized like a big guide plate and dampening device, which stabilizes the pushrod. Just make sure that there is no interference problems when turning the engine over on the engine stand."


http://www.mantonpushrods.com/Pushrod-Info.html


Joe

I agree, but for another reason.
The pushrod's upper end is moving in 2 planes (up & down for the cam lobe, plus in & out for the rocker arm sweep), therefore higher inertia.
The pushrod's lower end only sees 1 plane of movement, so it gets the heavy end.
Very small difference? Yes, but do it anyway.

Hmm very wise, I had not considered that
G

X2 I learned something today

I had a Smith Bros. ball and cup 3/8 pushrod break in the middle, around 5200 RPM during a dyno pull, causing one of the loose parts to get caught between the lifter tie bar and block breaking the top of the solid roller lifter throwing it out of the lifter bore and bending the other pushrod next to it, luckily that block had lifter bushings in it so loss of oil pressure during that pull.
They where made by Smith Bros., the company was here in Bend at the time so I had them custom make them for that motor. I took both pushrods, the one next to it was bent also, the valves in that cylinder where fine so it wasn't piston to valve cause carnage, the broken one had a visual flaw in the material where it bent and broke off. I had ordered and paid for 3/8x.120 wall 5/16 ball and cup drag race pushrods and when I took them back to them I was told they where .083 wall, not what I ordered and paid for Bottom line they replace both of them but did not offer to help me on the broken lifters and loss of use for the dyno that day t due to their part failure The cam lobe got damage by the other broken end of the pushrod when it fell into the lifter bore and cut into the cam lobe
I had the cam fix and put the motor back together to finish the dyno testing, I had Manton make me a set of their series 3 3/8x.120 wall and took that motor to another engine dyno, DTS brand, in Klamath Falls, OR for the rest of the testing. I made several pulls on the dyno to warm the oil and motor up and then recheck the lash before making two all out pulls to 7000 RPM, the motor made peak HP 6300 RPM on the other engine dyno and made peak HP at 6400 RPM on the DTS dyno. We then change the pushrods and went back through warming it up and making several more pulls after checking the lash again, that motor made 8 more HP at 6700 RPM with the better Manton pushrods in it
Their is power in pushrods, get the best one you can get for your build
Terry Manton had told me before he died the same thing about pushrod clearances to the block, heads and guide plates as in their discussion on the attachment on pushrods
I have seen shiny spots from rubbing with no visual contact when checking them on the engine stand on more than one pushrod in my motors after racing them with no damages or failures, so far

Ok so spent some time with it today.
When I first put it together for mock up I think I may have had a spacer in a wrong spot pushing the rocker arm closer to the tight spot .
Looked at it today moved spacers around so rockers were centered on valve tips and ended up with about .020 clearance at the tight spot , push Rod fat end down.
But tried it fat end up just for kicks and almost doubled the clearance.

Thanks for all the replies. Couldn’t do it without you guys!!

I would warm the motor up and recheck your clearances hot or warm
Maybe they will be wider