Push rod selection help please

[Demon James]

Just had heads skimmed and gone to set pre-load on my 440 Dart and it looks like some of the rods are less that straight.
Moreover, it appears that one cup has made contact with something it shouldn't have at some point in its life an the cup looks cracked and off centre.

I need to replace the full set and I'm after some help as this is my first time working with hydraulic lifters on an adjustable rocker.

The push rods are cup and ball and the rockers have CRANE cast on the underside (not ally so not yellow, blue etc)

To the best of my measurements, the existing rods are 9.122" in total and the cups are between 0.041 and 0.044 deep (does this give me an "effective" length of 9.08" to 9.078" ?

I have read read that there should be about 1.5 to 2 threads showing on the rocker adjuster, is this UNDERNEATH? as all mine seem flush, making the existing rods a tad too long and following a 0.010" skim they will be even longer.

I made an adjustable rod from an old one I have and my plan is to fit this and adjust the rocker to 2 threads proud of the underside as a starting point.

My adjustable rod gives me from 8.70" minimum to 9.30" maximum.

Should I set cylinder 1 with exhaust vale just starting to open and set the inlet? Happy to repeat in single steps rather than short cut alternating cylinders or whatever the pattern is.

Also, any recommendations on rod makes and suppliers please

[Demon James]

Rockers before I took the heads off.

[Dave999]

Turnip got me Smiths bros pushrods. NICE, not massively expensive, and good solid, not bendy race quality part and exactly as i specified.

Yes its the underneath side of the adjusters. if you wind too much out on the underneath side
1) if you oil the rockers through the pushrods the oil hole doesn't line up
2) too much leverage on that threaded adjuster causes them to snap

i.e you don't want 1/2 an inch of adjuster sticking out beneath the rocker


here is a ramble based on my own cowboy way of doing things....


adjusters and hydraulics PITA neither 1 thing or the other

you can cheat. sling in a set of pushrods with no preload, start the engine wait to see of it quietens off if it doesn't put 1 turn on each adjuster and be done with it....
there will be one that still clacks, just to annoy you, stick 1/4 to 1/2 more on that

you are not supposed to do it that way but i did for years with no ill effect... well plenty of problems but not to do with this


this might be wrong but

you had the heads skimmed = 0.0?? thou (check both sides of engine)
and you previously ran with the adjusters right in (no turns out) and it was fine, so one presumes you had preloaded standard amount
now your pushrods are too long... (or your lifters are just PUMPED right up to the clips in which case they may not be too long? did you run the car? )

so what you have removed from the head PLUS the distance you add when you wind the adjuster out 1 turn
is what i would have removed from the length of the pushrod

current pushrod length Minus (head shave thou + 1 turn in thou) should set you back to a point you were at before but with 1 turn to play with if too long.

now when you put them in you have 1 turn of preload you can remove or 1 turn of preload you can add without the adjuster miles out of the arm

test it with your adjustable rod But keep in mind without checking springs and the fact that you have hydraulic lifters you will have little view of if the lifter is fully pumped or completely flat making this almost impossible. a fully pumped lifter is not easy to un-pump it feels solid and some stay like that for minutes hours or weeks, even out of the car!!!! if full of sludge .

its easier to check with a solid lifter that has a seat height that is approx the same as the hydraulic, or you take your hydraulic lifter apart and stuff a ball bearing in under the the valve body to make it solid for this check.

if you check with a solid do it with the adjuster wound right in leaving 1 - 2 turns of preload for when you put back hydraulic

does the roller roll across the centre of the valve tip.... use magic marker (permanent marker) its not permanent on an oily valve tip and will show a nice roll pattern

do it twice, if the adjuster is wound in fully, and you get a good roll pattern across the tip, and its still pretty good with 2 turns on the adjuster you know that when you put in a hydraulic you can go up to 2 turns of preload and all will be well.

mopar valves with fat stems give a little more lea-way

my adjusters were UNF i could get 4-5 turns in before i started running the lifter at the wrong end the scale

i then swapped the lot out for a solid cam and lifters making life easier

summary

take what you had off the head off the length of a standard set of pushrods and you are in the right ballpark provided your rocker geometry was ok before, cater whichever way you want at the adjuster

if they were all sitting nose down or arse down and were obviously biased 1 way or the other then this won't work and the solid lifter and your adjustable pushrod are the only way

rocker should be at mid travel (mid ROCK)at mid point of lift at the valve.

i.e max lift at valve is .600 thou
turn the motor over so the valve goes .300 thou down the guide (7.6 mm) i won't suggest a steel rule but hey..... if the rocker is in the middle and nothing hits anything at no lift or full lift

all good.


dave

[Dave999]

ah i see you rockers are not roller tipped

no problem marker pen still works

but i also see you have a dent in the top of each and the rocker arm bolts to act as reference for mid point in travel....which helps

mine are easier big square chunks with faces that are parallel to the rocker tin rail easy to see mid point...Mmmm



dave

[Blue]

Hughes engines website - instruction sheets- 2a pretty much goes through the process..

[Demon James]

Had a play after work and I consistently found that a rod 0.161” shorter than what I have seems good.

None of the adjusters in the rockers had any thread showing so I removed a rod and wound the adjuster down with fingers to show 1 1/2 to 2 threads protruding. Then put my adjustable rod in place and extended it to sit snug without pushing the lifter inner down. All done with valve fully closed.

Fettled with rod length and rocker, noted length and went onto the othe intake and exhaust valves.

Some lifters have bled down much more than others but they all moved to varying levels so I’m happy they are ok. With the ones that have bled down I’ve been careful not to over set the rod length.

I will have a read up, Blue before committing to a final length

[Pete]

Good bit of work, James.
We changed the Head Gasket thickness on the 500 Hemi and ended up having to change the push rods as a consequence.

[MrNorm]

Manton or Smith Bros...won't go wrong with either

[Demon James]

Took a video of valves turning motor by hand but its too big to post from my phone.

Here's a still shot showing intake valve opening whilst exhaust is till open as it travels to closed position, is this because the hydraulic lifters are not full or by different amounts?

Yellow line is vale edge and red is cylinder head opening edge.

[Demon James]

school boy error, just had my first lesson in valve overlap

[Dave999]

yeah that's all ok


what you don't want is the edges to hit each other (on a semi hemi or hemi, you valves are parallel you don't need to worry)
or for either of them to hit the piston.

so all good

here is a chunk of stuff that might be of interest

http://cochise.uia.net/pkelley2/DynamicCR.html

[Demon James]

Cheers, Dave. Feel a bit of a wally, but always willing to learn

One thing I don't seem to find an answer to though, hydraulic lifter full or empty?

When you fit new lifters you are setting the zero lash against the small spring inside the lifter, OK? So when you add a half turn (for example) to pre-load, this compresses that spring by, lets say 25 thou.

As my engine has been running for two seasons, I have oil in it and therefore the lifters. Some have bled down a bit and others haven't. Everything is clean and with enough pressure you can see oil weep from the lifter ( on those I tried).

When I set the zero lash on a lifter that seems to move internally by about 50-60 thou I can then add the half turn to the adjusters which pushes the rod slightly into the lifter.

If I use the same method on a lifter with little or no movement in it (ie, full of oil) I set the zero lash by rolling the rod in my fingers until it no longer has any up and down movement and just the slightest resistance to my fingers turning it. When I then add a half turn to the adjuster, the vale spring compresses thus opening the valve a hair or so.

My question is, should I remove all the lifters and let them bleed down ( or assist by pressing down to push oil out) before I fit my new rods?

I have based my new rod length on all the lifters that sat in the neutral position.

[Dave999]

you can take them all out squish them in a vice (gently) to get the oil out or dismantle them.

its a right old pain in the butt for little gain.

so your method sounds fine to me
the spring pressure of a partially bled down lifter can be felt at the pushrod.
set for zero lash with little pressure on the lifter spring then add preload to spec.

those that are pumped up set in the same way, there is just no "GIVE" when you apply pressure to the end of the pushrod and yes they may hold the valve open a smidge until the engine moves and oil can flow through the internal valving in the lifter.

set em up then spin the motor on the starter with no plugs

have a cup of tea and any valve that was open due to pumped lifters will be closed

plugs back

run it and see how it is

if any valves are still hanging open then maybe the lifter was not pumped up. maybe its jammed down. highly unlikely if they are new and decent quality. however the insides can collapse and jam if they are old, you have had a catastrophic happening (like one that bends pushrods) or you are running the kinda valve spring that would normally be used with an exceedingly high lift roller cam i.e huge spring pressure, which you are not supposed to use on hydraulic flat tappet lifters.

[Demon James]

Thanks mate, that makes sense just wanted to be sure as from a first timers view, the setup seem a bit random.

I'll enjoy that cup of tea