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Which pushrods to use ?

I'm putting a black "EFI" head onto my red 202 motor.
Do i need to find pushrods from an EFI (black) motor or can i use either of the following sets out of one of the motors that i have laying around here.....

Black "carby" 202 pushrods ?
Blue 173 pushrods ?
Red 202 pushrods ?
Red 186 pushrods ?
Red 173 pushrods ?
Red 161 pushrods ?

If i do need black "EFI" pushrods, Would anyone have a set they'd be happy to part with (or is buying NEW recomended) ?

If it makes any diffrence to choices, I've just had 20 thou shaved from the EFI head and will be using a new mild cam and new lifters.
Appreciate any input :-}

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Pushing Dusty

Its best if you use new Pushrods as well that way then they aren't worn into the old lifters and score the top of the new lifters.

Daniel
0428 319 883
(Postcode 3030)
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"My Shed"

Dusty Pushrods

202 rods are longer - so in theory if you use 202 rods with the shaved head and cam - the valves will open further giving better airflow.....

sounds good to me....

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Push rods

IMHO you are best going with new ones. As stated above some are longer. So you will need 202 specific ones.
As far as the head being shaved affecting the valves. You will most likely need to use shims to set the lifter preload.
Cheers.
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Campbells Shed
Postcode 3123.

186 / 202 pushrods

186 pushrods are longer than 202 pushrods, by 3.05 mm.

The length of the pushrods has nothing to do with how far the valves open, that is dictated by the cam lift and the rocker ratio.

If you use longer pushrods the lifters will self-adjust for zero lash, and you will be back to where you started from, as you should be.

If the pushrods are too long, then the lifters will bottom out and the valves will be held open.

You can use 202 pushrods in a 186, because the 186 heads have preload adjustment on the rocker studs. Everything will be OK unless you run out of adjustment before the correct preload is achieved. If the head has been shaved then this should not be a problem. I had 80 thou (2.0 mm) shaved off a 186 head once, and I used 202 pushrods because it bought the rockers back closer to the original angle.

If you use 186 pushrods in a 202 then the non-adjustable rockers may cause the lifters to bottom out. This will be made worse if the head has been shaved.

Brett.

lifters will self-adjust

If you use 3.05 mm longer pushrods the lifters will not self-adjust for zero lash, and put you back to where you started from.
Lifters will preload to about 0.060".
3.05mm is about 0.120". So your valves would be sitting about 0.060" open. Plus whateven has been taken off the head.
Cheers.
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Campbells Shed
Postcode 3123.

lifter preload limit

As I said: "If the pushrods are too long, then the lifters will bottom out and the valves will be held open."

And I dispute that the lifters only have 0.060" travel. The EH workshop manual says that 1 turn of the adjusting nut from the zero lash point will place the lifter piston at the mid point of travel. The head stud is 3/8 UNF thread, i.e 24 TPI. that means that 1 turn of the nut will push the rocker pivot point down by 0.041".

Taking into account the rocker ratio, this will compress the lifter by about 0.070".

0.070" is the mid point of travel, so total possible lifter travel will be about 0.140".

Brett.

Brett.

Preload limit

I'll notice that happening, surley.

Thanks for all the input as scary as it was :-)

"Republic of Dusty's Shed"
EMAIL
(postcode 3380)

"Don't walk away in frustration...Kick the crap out of it"

EH workshop manual

I'm not sure why you are refering to an EH manual. They have adjustable rocker gear. The later heads, as Dusty is using, have non adjustable valve gear. On top of this the later heads use metric threads. So one turn would give a different measurement.
I did not say the lifters only have 0.060" travel. I said that the lifter wont want to preload more than this and will hold the valve open once it gets some oil in it.
Even so, working with the EH figures. The rocker ratio on a 202 is(IIRC)1.5:1. So if that were applied to 0.041" you would get 0.0615. Granted that is almost 0.070". But it doesn't work like that. With a closed valve and the pivot point lowered by 0.041". You would get 0.027" preload on the lifter. Which IMHO would be perfect(and near on 1/2 of the 0.060" preload range I mentioned).
Cheers.

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Campbells Shed
Postcode 3123.

principles of leverage and lifter preload.

I know it doesn't work like that, and I can explain why. Your theory and calculations are incorrect.

During normal operation the rocker behaves as a class 1 lever. The fulcrum is toward the middle of the lever (at the rocker stud), the effort is at one end (the pushrod) and the load is at the other end (the valve). As you have said, the rocker ratio is 1.5:1. This means for every unit of travel at the pushrod end, the valve end will travel 1.5 units. This is because the distance from the valve end to the rocker stud is 1.5 times longer than the pushrod end to the rocker stud.

But, during the lifter preload adjustment the valve does not open. The valve end of the rocker is now the fulcrum point. The rocker has changed to a class 3 lever. The fulcrum is at the valve end, the effort is at the rocker stud and the load is at the pushrod end.

In a class 3 lever the amount of travel at the load point is always greater than the travel at the effort point.

If you transpose the relative dimensions of the class 1 lever into the dimensions of the class 3 lever, then the velocity ratio (and therefore the travel ratio) becomes 1.67:1. For every unit of travel at the rocker stud, the pushrod end will travel 1.67 units. (1 + 1.5)/1.5 = 1.67.

So if the rocker adjusting nut is turned down 0.041", the pushrod, and therefore the lifter plunger, will compress 0.068".

I referred to the EH workshop manual because we were discussing hydraulic lifter travel range. EH's had hydraulic lifters.

It also does not matter where abouts in the lifter travel range the preload is set at, as long as it is not bottomed out. The lifter will not fill with oil and hold the valve open. The oil pressure supplied to the lifter is not sufficient to open the valve. If the valve is held open then either the lifter is faulty, the valve spring is broken or weak, or the oil pressure is excessively high.

The non-adjustable rocker gear uses exactly the same principle of preload as the adjustable rocker gear. If you fit the rocker bridges, but leave the bolts loose, there is about 0.040" clearance between the mating faces of the rocker bridges and the head at the initial point of zero lash. Torquing the bolts will lower the pivot point by 0.040", and therefore compress the lifter by 0.068".

Brett.

Principles of leverage.

My appologies Dusty and Brett.
I don't know if at the time of writting it had been too long since I was in a class room. Or too long since I'd slept(I suspect both). But as soon as I read the words, "Principles of leverage", in Brett's above reply. My days in the classroom came flooding back.
Brett's figures are correct. So disregard mine to a degree.
I knew I was right about the preload setting being 0.060 odd thou. But I was thinking that was the max preload.
0.060" is the desirable figure. Not the max.
Regardless of this. I still reckon you will be sweet to just slap it all together as per factory. That cam is a billet. Not a regrind. So it's base circle will be normal and you wont need longer pushrods or such.
Cheers.

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Campbells Shed
Postcode 3123.

Lifter Preload

Note that within 2 minutes of setting Lifter Preload on a perfect Lifter Preload disappears because the Lifter ramps down to set the Valve Lash to zero.

Oil under the Lifter Plunger will squeeze between the Plunger and Body as it's supposed to.

The Lifter works exactly like an hydraulic door closer. It's purpose is not to hold the door open but to slow the rate of movement of the door.

Preload in a Diff Pinion is permanent so the term Preload is not the ideal word to use in this case but has probably been used to simplify the process for mecanics.

"It also does not matter where abouts in the lifter travel range the preload is set at, as long as it is not bottomed out."

Agreed, but there must be travel space left after torquing down to allow for expansion of the Valve Stem.

T

Shed
Holdenpaedia, they're the brakes Mate.

Expansion of the valve stem,

Expansion of the valve stem, expansion of the pushrod, and valve seat recession.

Brett.

Agreed

But Valve Stem Expansion will kick in much sooner than the rest of them because the Valves are closest to the heat source.

At the very first lengthy idle at traffic lights I say from experience.

T

Shed
Holdenpaedia, they're the brakes Mate.

Empty Lifter

If you cycle an empty lifter, its travel is around 1/2".

Certainly any head shaving, gasket thickness or pushrod length needs to be taken into account.

A simple rule of thumb is to watch the degree of compression as the Rocker Bolts are torqued down and ensure that the degree of crush leaves enough travel for Valve Stem expansion.

I'd find Campbell's 0.060" figure typical for the standard non-adjustable heads on which I've torqued Rocker Gear.

T

Shed
Holdenpaedia, they're the brakes Mate.

202 longer then what 186 are

202 longer then what 186 are longer then 202.

Pushrods

Okay, guess new ones it is.
So if i order std legnth hardened pushrods to suit EFI black motor, the lifters will self adjust and require no shimming ?
I'm confused enough without throwing shims into the mix, lol.

"Republic of Dusty's Shed"
EMAIL
(postcode 3380)

"Don't walk away in frustration...Kick the crap out of it"

throwing shims into the mix

How much was skimmed off the head and has the block been decked?
Cheers.
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Campbells Shed
Postcode 3123.

Shimed Campbell

Aww bugger!!!...we must have been typing at the same time :)
I think you are also on the right track Campbell, shims are a good option.
I have used shims in race engines with sucess..although sometimes we used them to create "solid lifters" ;)
Q-ball.

"Clay is for racing on,Tar is how you get there!!"
My Shed
3401

Slow typing

I'm slower since i type half then do something else then finish my post, lol.
I will buy what i need through HPEngines so hopefully Shane can gimme the final word on my needs.
Gotta clear off while the kids do some homework on the puter.
BBS.

"Republic of Dusty's Shed"
EMAIL
(postcode 3380)

"Don't walk away in frustration...Kick the crap out of it"

Push Rods for Dusty.

If you talk to Crow Cams to order your push-rods, they may be able to work out the exact length you require by the information you have given us.
202 & 3.3 (including efi)have the shorter push-rods.
To be honest, I would fit the new cam & lifters & use a good set of used 202 push rods. However, if you have the extra dollars reqired for new push rods, then it is cheap "piece of mind" :)
Q-ball.

"Clay is for racing on,Tar is how you get there!!"
My Shed
3401

Campbell

Well i've no idea about the block being decked as it's the 202 red motor that's in my HX.
It's a fair chance that it's been reco'd not too long back as it's a good tight motor and looks like new gaskets everywhere, maybe has a towing cam (?) but only guessing as i've never had the head off her and don't know any history of the car prior to my buying it.

The head is that one i got from you and i've had 20 thou taken off to clean up the surface and i shall lap the valves and fit new valve stem seals.
I'm also using the cam and straight cut timing set i bought from you.
I will buy new lifters and a set of hardened pushrods.

Not that the rest is relevant but i'm also doing....
HEI ignition and Brisk LGS plugs
Aftermarket two barrel 12 port manifold and 34ADM Weber
Extractors and free flowing 2 or 2.5 inch single exauhst
also changing to 4 speed aussie.

That's about the best info i can give you mate.

"Republic of Dusty's Shed"
EMAIL
(postcode 3380)

"Don't walk away in frustration...Kick the crap out of it"

good tight motor

Sweet. It would be unlikely the block has been decked much(if at all)and 0.020" is nothing to cause worry. Just get std length 202 push rods. At the very worst you may need to shim the rocker bridges .010"(ish). But I'd be surprised. I'd expect it would all to fit up as per factory.
Cheers.

email
Campbells Shed
Postcode 3123.

Shimless :-)

Phew, I really don't need shimming complications... When i dropped the head off, i asked if 20 thou would upset anything and the machinist said 20 was nothing and wouldn't affect anything so i'll carry on as i am but if any shimming is required, how to tell ?
What would happen if it does require shimming but i fail to notice, reassemble and start/run the motor ?

Footnote..I only decided to shave it to remove some marks in the gasket surface :-)

"Republic of Dusty's Shed"
EMAIL
(postcode 3380)

"Don't walk away in frustration...Kick the crap out of it"

Non-Adjustable Lifter Info

For street use Dusty, I would simply watch the degree of lifter preload as you torque each Rocker Bolt down.

As I said in a post above, the lifter has about 1/2" travel. Find a new and empty lifter and measure this for yourself to confirm.

Make sure you use new Rocker Bolts, that both the Valves are in the closed position and tighten each Rocker Bolt slowly to allow the Lifter time to ramp down. Old Rocker Bolts may have stretched.

Make sure you torque the Rocker Bolts to the *exact* figure. Too loose and the Lifter will rattle. Too tight and the Bolts will stretch and the Lifters will also rattle. You'll also crush the Rocker Saddle out of shape.

As an example, make sure the preload is no more than half the lifter travel you measured for the empty lifter and you'll be OK.

If you can't get this measurement, then you'll need to look at Shimming alternatives.

Shimming without measuring first is likely to cause Lifter rattle which will wear out the Valves, Seats and Cam fast.

I know Ben Simpson adds shims anyway but he is after track performance and aims to avoid Lifter Pump-up which double valve springs tends to keep at bay better than a red Engine unless you are sustaining peak revs.

His philosophy is that the Lifter never gets preload so it never gets the chance to pump up.

More info here ...

http://holdenpaedia....

T

Shed
Holdenpaedia, they're the brakes Mate.

Holden part numbers ?

Would someone have the part numbers for genuine holden rockers and also rocker bolts (Black EFI head) please ?
I assume these can be readilly available from any Holden dealerships ?

"Republic of Dusty's Shed"
EMAIL
(postcode 3380)

"Don't walk away in frustration...Kick the crap out of it"

marking

Cheers, Tom

tom.kelly.x2@hotmail.com
Check out My Shed

Help please!!!

i have just built a blue 202 from ground up, got the head shaved and new larger valves, new cam with new lifters. put the pushrods in and tightened the rockers. the pushrods rattle up and down with about 2 mill well some do some dont while valves are closed. i replaced them with 186 rods cause there longer. my question is i tighten the bolts by hand till zero lash and then its about 3/4 of a turn till there torqued. the valve spring compresses first and then the lifters catch up and compress. can i run my car like this. or is this bad. thanks for any help


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