HEMI Tech- Rockers, valves, pushrods, springs

Well said Tom.
There are far too many folks attempting to use 'brand-x' style engine rebuilding tricks on the EarlyHemi engines and it rarely works out well. Some 'brand-x' parts can be made to work but many are just too labor intensive and using the correct part up front ends up being faster and cheaper.

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Another option is to keep the lift to a reasonable amount so you don't need to get longer valves. The theory that if a lot is good, too much must be better certainly doesn't apply here. Don Johanson and Natchi Contareras were a great help in coming up with a roller cam to work with the stock rocker geometry.

Not quite sure where the break is on lift but we managed around .525 at the valve.
The rocker geometry is about as extreme as I'm comfortable with. That said, quality parts and machine service from both Tom and 73RR is what makes my combo work.

 

Nice post Tom. I was thinking in wedge head technology and the way you explain it helps.

 

The geometry is one place where it is very hard to cheat, especially when using the .875 stock diameter shafts with stock stands.

 

Be sure to get the rocker arms magged. I put a set of Crane springs for a ford on my 341 Desoto and an exhaust rocker arm broke shortly after the first startup. It wasn't that the springs were too much, but rather than there was already a crack in the rocker arm that apparenlty had been there for a very long time. There was rust about a 1/16" deep in the crack.

 

Anyone got an easy way of removing the first rocker shaft plug?...the second is a cinch with a long punch, but it's getting the first one that takes time. I did drill a small hole, inserted a screw and made a small slide-hammer tool...but the plug is so thin that it just pulled the screw out.

 

Drill 1/4" hole in plug, put a long rod and knock out the opposite plug. Then turn the rod around and knock out the 1st plug.


Ago

 

Hey thanks for the heads-up Ago, that worked well.


There was an amazing amount of "Dodge cholesterol" inside and totally hidden from view. Next - Off to the hot tank!!!





Most of the oil holes in the rocker shafts were blocked, as were the oil holes in the intake rockers....lack of oil leading to the hollowed out rocker tips...above.

 

Dodge rockers are known for galling inside the pivots, as well as the tip wear.

 

I feel a little nervous questioning "Mother Mopars" way of doing things, so maybe this is a dumb question, but has anyone ever hard-faced the valve end of the rocker arms for better life? Or does that somehow cause another problem?

I guess if there is adequate oil flow, then there shouldn't be a problem.

Just thinking out loud...

David

 

The ends are hard from the factory. They wear like the one shown when the oil gets shut off to the end.

 

I would think the rocker shouldn't be as hard as the the valve stem. Would you prefer to replace a rocker arm or a valve?

 

If the hardening is significantly different between any two parts that beat on each other then the softer part will fail even with oil.
As long as the engine is in proper working condition (getting oil to where oil needs to be) then the valves/rockers will last a verrry long time.

Given what we see in the photos it is no surprise that some damage occured.

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Question for someone that might know?

Background:
I have a 1957 392 and I am using a set of 1955 331 heads. I'll be using hydraulic lifters and can buy either 1/4 inch or 5/16 for them. I have factory adjustable rockers.
Question:
Will I be able to use factory push rods? ....or am I going to have to have a set made?
Regards,
George

 

Why not?

 

I don't know if the heads are the same height ? Ie: will 392 push rods be the right length when using a 331 head? The exhaust or longer push rods out of the 331 are right at 11 inches long. I do not have any 392 push rods to compare them too???
As a side note : The adjusters have 1/4 so both ends are 1/4
regards,
George

 

...better double check that dimension before you bolt it together.

You seem to have several variables to deal with regarding the pushrod length and the oem adjusters have limited amount of travel so you should mock up the parts and see how close the 392 pushrods are.

.

 

Because of the higher deck you'll need 392 push rods. I've assumed that the height of 331/354/392 heads are the same. They should work, between the hyd lifters & the adj rockers, depending on if the block and/or heads have been milled

 

If your adjusters are 1/4, they are not factory. The factory adjustables will accept 5/16 or 3/8 ends. ( I have seen both)

 

Thanks...I used the 1/4 push rod from the 331 and just thought they fit...... grin

Are 392 push rods 5/16 for both non adjustable as well as adjustable rockers?

OR 1/4 for non adjustable?

 

All non adjustables used pushrods with the tapered .250 end.

 

Some other things to think about:

Verify the alignment of the cooling passages in the two lower corners. (block-to-head)

The lobe seperation is different on a tall block vs. a low block. Depending on the cam profile, the pushrods may bind up in the pushrod holes on the heads unless the holes are oval-shaped (by hand).

You'll need spacers between the heads and intake unless you're running a log-style (carbs or fuel injection) maifold.

 

Hi David , is this what your talking about . Its 3/4 the ways down on this link .
http://www.hemihaines.com/Early-Hemi-Engines-6-146.html

Don

 

I am changing my lifters to HT-812, the ones for the early 361 - 413 B/RB engines. I currently have adjustable pushrods with 5/16" ball end at the lifter. Will these work with the above lifter. thanks
Bill

 

I've been doing some research on the "beehive" valve spring technology that is available now. I got ahold of Hughes Engines, a company that specializes in Chrysler big and small block performance and they told me that if you used an 11/32 valve stem you could make one of the beehive spring designs work in an early Hemi cylinder head application. I brought this up to my engineer friend Tom Burkland and he was telling me that the beehive design has a lot of advantage and would be a good choice if I could find a compatible spring application and make it work on the early Hemi head. I'm just curious if anybody has done any thinking on this or has used them on a Gen I Chrysler Hemi.

 

I have looked at the beehive springs for a couple of projects although did not end up using them.
A similar application will be for the LA engine.
Be cautious, do not cut the spring pocket deeper to accommodate a too-tall spring or too-long valve. The casting is a bit thin and water lurks beneath.

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Is anyone running a flat tappet solid lifter cam and, if so, are you having issues with the occasional pushrod eating it's way into the oil hole in the rocker arm?

 

might be a silly question Skip but is the oil passage from the shaft part of the rocker to the tip clear? I'm sure you checked that but it's a thought.

 

That's not the issue. Hard chromed shafts, hot tanked and refurbished rockers, everything's clean and there's plenty of oil getting to the rocker assemblies.

The issue is the intermittent lack of contact between the pushrod and the rocker when the lifter is on the base circle.

When the pushrod comes back up again, it slams into the rocker arm and, eventually, starts to wear itself into a point....right into the rocker arm oil hole.

The issue only occurs when slack is allowed to occur at the pushrod end (a necessary evil with solid lifter cams). Hydraulic cams don't exhibit this problem unless a lifter fails (and slack is allowed to occur)

 

What are you guys doing to remedy this phenomenon? ...or do your cars only come out of the trailer when ist's sunny?

I fixed mine years ago but I've run across two (street driven with decent mileage) in the past three months that have the issue.