Choosing pushrods for my 440

[Wietse]

Hey guys,

I have been working on my '69 440 engine, i had a some issues with the engine and decided to dismantle the engine and check my camshaft as i did not know what was in there.
After that it went downhill quite fast, found the camshaft set advanced 1 tooth on the cam gear etc. (full story here: https://www.forbbodiesonly.com/moparforum/threads/degree-an-installed-unknown-camshaft.175657/ check the last few pages)
As the valve geometry was also not up to spec i purchased and installed a correction kit from B3 Racing.

Now the time came to select a new push rod length that it will need, the old ones are 3/8" OD, and, i assume, they have the 5/16" ball/cup ends.
I want to continue using this size as it will be seeing around 340 lb of spring pressure at full lift.
The length required from what i found so far is around 9.315" (want to double check this once more before i decide) and i found Comp Cams has a set 3/8" @ 9.400" length.
(Push rods part number: Comp Cams 7432-16)
I will not be running much pre-load on the lifters, before it had almost no pre-load at all but i guess i will be around 0.020"-0.030".
My main concern is wall thickness, is 0.080" ok for a street/strip type car?
I will not be racing it but since the cam is quite a beast i want to make sure i do not go too light on push rods, as well as it being too heavy does not help either.
It is a hydraulic flat tappet cam, lift is about .580" range.

Any advise on these push rods?

 

[khryslerkid]

Don't mess around with catalog parts...

https://www.pushrods.net/?gclid=EAIaIQobChMIkPrF5KWz5gIVCNbACh0ZtAW1EAAYASAAEgKqlfD_BwE

 

[Wietse]

I found that there were 2 push rods that show some numbers on the side, 0.375" OD x 0.291" ID.
So wall thickness is only 0.042" on the old ones, do i really need 0.080" or more?
I believe adding unneeded weight is also not something i want right?

Don't mess around with catalog parts...

https://www.pushrods.net/?gclid=EAIaIQobChMIkPrF5KWz5gIVCNbACh0ZtAW1EAAYASAAEgKqlfD_BwE

Not bad prices for any custom size push rods!
For me it would be these: https://www.pushrods.net/product-page/381-series-9-to-10-inch-length
It does not tell what end style it is, ball/ball or ball/cup.
Guess i can contact them and provide the details to get the right set.

 

[threewood]

Agree with KK...Smith Bros. is who you seek...
https://www.pushrods.net/custom-pushrods

What heads are you running? I would think 3/8" are overkill for a street motor and may rub the heads. Call them and see what they recommend. What rocker arms do you have?

 

[threewood]

I found that there were 2 push rods that show some numbers on the side, 0.375" OD x 0.291" ID.
So wall thickness is only 0.042" on the old ones, do i really need 0.080" or more?
I believe adding unneeded weight is also not something i want right?



Not bad prices for any custom size push rods!
For me it would be these: https://www.pushrods.net/product-page/381-series-9-to-10-inch-length
It does not tell what end style it is, ball/ball or ball/cup.
Guess i can contact them and provide the details to get the right set.

They have an order sheet where you can specify the ball or cup. I used it as a guide when I called them. I'm just about 390 at lift and have 5/16" normal wall thickness. Make sure you don't have too much thread showing below on the rocker arm.

 

[Wietse]

Heads are stock 906 heads, the 3/8" push rods i used before had no clearance issues.
Rocker arms are some old days Mopar Performance type 1.6:1 ratio type. (see picture)

As per their instruction i should set the adjuster to expose 1 thread below the rocker arm, then set the adjustable push rod to that length and that's it.
Then comes the pre-load in to play, the camshaft is from Hughes and they recommend 0.080" - 0.095" pre-load.
On the old setup the pre-load was set to a bare minimum with being just off the retainer ring.
I think for a safety margin i would go to at least some pre-load of 0.020" because i am not sure i should run the high amount of recommended pre-load.
Before the B3 geometry kit installation i found a 0.100" piston-to-valve clearance, now with the B3 kit i will have gained some valve lift and the PV clearance is probably a little less now. (still need to check once i got a push rod length confirmed)

I just found this list on Hughes website with push rod recommendations:

From this a 5/16" 0.049" heat treated rod would do well.
But as others say, go with the biggest size push rods you can fit in there to avoid flex.

 

[khryslerkid]

I found that there were 2 push rods that show some numbers on the side, 0.375" OD x 0.291" ID.
So wall thickness is only 0.042" on the old ones, do i really need 0.080" or more?
I believe adding unneeded weight is also not something i want right?



Not bad prices for any custom size push rods!
For me it would be these: https://www.pushrods.net/product-page/381-series-9-to-10-inch-length
It does not tell what end style it is, ball/ball or ball/cup.
Guess i can contact them and provide the details to get the right set.

Call them. They will know what you need by telling them what you have. They know their $hit !

 

[Wietse]

For me better to send an email, all this tech stuff to discuss over the phone is not that easy for me.
But as you said KK, i will ask them what they recommend.
I will finalize the total length measurement tomorrow and will ask them for their advise.

 

[Lefty71]

Don't mess around with catalog parts...

For sure. If I were you (and this is what i did). Use a checker tool to determine the length, then take the checker to your machinist, and have him call Smith Brothers for you. That way you won't screw up on the learning curve of end-to-end, center-to-end, ball-cup engagement, ball radius, yada, yada. I would advise the 5/16 pushrods, because they will give you more room in the tunnel without scraping like a 3/8" might, given the added length. 5/16 will be plenty tough enough, if you go with Smith Brothers! HTH, Lefty71

 

[Wietse]

I have been in contact with Smith Brothers, they said i can stick with the 3/8" push rods and using the 5/16" ball/cup configuration.

Now i have came at a length of 9.40" (end-to-end) and now i need to figure what pre-load i can run on the hydr. lifters.
In the previous setup there was actually a very small amount of pre-load, it was set just off the retainer.
But now i want to have some insurance in there to avoid hammering the retainer so what is a safe pre-load to run?
I was thinking to set 0.020" - 0.040" of pre-load. (1/2 turn - 1 turn on the adjuster, 3/8"-24 threads)
What would be a safe setting without going to some un-needed size?
I mean what would make me set it at a certain pre-load?
I learned that it also depends on material of cylinder heads (cast/aluminium) for heat expansion, mine has stock 906 cast heads.
I have more then 0.100" piston-to-valve clearance, still need to confirm actual clearance but i've never came close to 0.100" while doing a quick check.

 

[Wietse]

Hey guys, some update.
I received and installed the push rods ordered at Smith Brothers, looking good what they make.
They are 3/8", .065" wall thickness and 9.300 effective length, 5/16" ball/cup style.
For now i have set them with 1-1/4 turn pre-load, 0.050"
After some more research around i think i will go back to 0.040" (1 full turn on the adjuster)
I found that Hughes engines are using Hylift Johnson lifters, the recommend running 0.020" - 0.040" of pre-load.
These lifters are used and several years old for sure and they are probably some older version that where purchased with the camshaft (Hughes Engines cam).
With having stock 906 heads i believe i will not require too much pre-load anyway.

Checked all the rods when installed and they have no clearance issues with the heads, not even close.

Thx guys for the advice, Smith Brothers do a good job in advising.

 

[Lefty71]

Smith Bros makes some really nice stuff. Definately could have been a smidgen longer on the pushrods. Whats the sweep look like on the valves with that correction kit??

 

[Wietse]

Smith Bros makes some really nice stuff. Definately could have been a smidgen longer on the pushrods. Whats the sweep look like on the valves with that correction kit??

What do you mean? These push rods could have been longer?
The adjusters are barely showing 1 thread, and i did not want to go higher because of the oil hole providing oil to the push rod cup sits quite low on the rocker arm.

The sweep is now perfect, 0.035-0.040" and centered.

 

[Challenger340]

Hey guys,

I want to continue using this size as it will be seeing around 340 lb of spring pressure at full lift.
It is a hydraulic flat tappet cam, lift is about .580" range.

I would not recommend you attempt Cam Break-in on a Flat Tappet Cam above 300# at full lift, 280# is even better.

IMO,
you are well advised to remove the inner V/Springs for the Cam Break in procedure, to lower the V/Spring pressure at full lift to below 300#.
then
re-install the inner V/Springs after the cam Break in.

You may wish to follow up with Hughes Cams to confirm this advice, ask Hughes if they are going to warranty any Cam Lobes run-in at 340# V/Spring pressure Full Lift ?

Question;
What makes you believe .035" to .040" is perfect sweep on the V/Tip ?

 

[Wietse]

I would not recommend you attempt Cam Break-in on a Flat Tappet Cam above 300# at full lift, 280# is even better.

IMO,
you are well advised to remove the inner V/Springs for the Cam Break in procedure, to lower the V/Spring pressure at full lift to below 300#.
then
re-install the inner V/Springs after the cam Break in.

You may wish to follow up with Hughes Cams to confirm this advice, ask Hughes if they are going to warranty any Cam Lobes run-in at 340# V/Spring pressure Full Lift ?

Question;
What makes you believe .035" to .040" is perfect sweep on the V/Tip ?

It is not a new camshaft, it has been in the engine for years already.
I always doubted how the engine ran, poor vac, poor idle, etc.
When i opened the engine i found it advanced an additional 14* by installing the cam sprocket 1 tooth out of line...being wanted or mistake..who knows.
After checking everything (who knows what more was wrong) i came to the conclusion that i had many more issues and there fore had to start from the beginning.
Spring pressure was not correct for this camshaft, spring installed height was not good.
After contacting Hughes Engines about my camshaft i went for the springs they recommended for this cam and set them to the correct installed height.
After installing the B3 kit i had raised my rocker shaft so i also needed new push rods.
The engine is still the same, just with a correctly installed camshaft and proper setup done on the valve train.

The sweep was too wide. (0.070 - 0.075")
After contacting B3 racing he made me a perfect geometry correction kit to reduce the sweep to half of what it used to be.
The 0.035-0.040" sweep is not my statement of being perfect, or the best for that matter.
But it is a big improvement of how it was, and after reverting back to Micheal from B3 he confirmed that is the reading he expected when fabricating my setup.
It all depends on what parts you use, type of rocker arms, how much lift your cam produces...etc.