273 hydraulic cam/pushrod/adjustable rocker combination.

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Update, after purchasing a pushrod checker, a length of 7.070 gave me a good pattern across the valve stem. I then ordered a set from Smith Brothers Pushrods, they were very easy to work with and shipped them out two days later. I also had to shave .060 off the intake to get the ports and bolt holes to align. Changing the intake gave the car better low end torque and an awesome throttle response. Thanks to everyone for your input...
 
Not that it makes any difference but those are probably Crane adjustable rockers. They had the lock nuts instead of the interference fit adjusters like the stock ones.
 
jh66cuda said:
Update, after purchasing a pushrod checker, a length of 7.070 gave me a good pattern across the valve stem. I then ordered a set from Smith Brothers Pushrods, they were very easy to work with and shipped them out two days later. I also had to shave .060 off the intake to get the ports and bolt holes to align. Changing the intake gave the car better low end torque and an awesome throttle response. Thanks to everyone for your input...
Click to expand...
Post a video if you can when you get it running.
 
hope they are crane
if they are coverted from the interference thread stock ones then be sure the cast iron where the jamb nut sits is flat- use a big file
do the mid lift test
at half lift see if the top of the valve tip lines up with the center of the shaft
you can use the retainer and a machinist ruler to eyball it
usually not a problem unless you have long valves or a really high lift cam (or both) but...
if that checks out you do not need to relocate your shafts
then open up the push rod holes
some high lift applications we use cups on the adjusters and ball and ball pushrods - not necessary with your lift
that cam duration is at SAE= .006 at the valve or .004 at the cam with 1.5 rockers
more like a 280 @.006 cam
Factory rated that cam at what - the stock 340 cam was 268 and the 4 speed cam what 272? I forget but the equivalent of measuring at around .008
It's not a "290" class cam
 
jh66cuda said:
Just in the process of swapping out my intake with a LD4B on my 66-273. I decided to do some preventive maintenance and check the rocker arm adjustment. The engine has and Melling 23203 hydraulic cam (specs below) with Melling MPR-155 push rods and adjustable rockers. To my surprise there was very little preload on the lifters and most were set a zero lash. Also noticed that there were a couple push rods that appeared to be bent. After removal it looks more like the top cup wasn't on straight. I did some digging and the MPR-155 should have an over all length of 7.342, mine measure 7.186. I also attached a picture of where the push-rod travels through the head, a couple of the rods that appeared to be bent were actually hitting on the head.

Any thoughts or ideas would be greatly appreciated.



  • Advertised Exhaust Duration: 298 deg
  • Advertised Intake Duration: 288 deg
  • Basic Operating RPM Range: 2800 RPM
  • Cam Type: Hydraulic Flat Tappet
  • Computer Controlled Compatible: No
  • Exhaust Duration at .050 inch Lift: 224 deg
  • Exhaust Valve Lift: 0.466 in
  • Exhaust Valve Lift with Factory Rocker Arm Ratio: 1.50 in
  • Intake Duration at .050 Inch Lift: 214 deg
  • Intake Valve Lift: 0.444 in
  • Intake Valve Lift with Factory Rocker Arm Ratio: 1.50 in
  • Lifter Type: Hydraulic
  • Lobe Separation: 112 deg
Click to expand...
The pushrod looks like its rubbing the bore on the head?
 
MOA said:
I have a 318 with same set up, adjustables with hydraulics. Cam is almost identical to yours, not that it matters.

I took .010 off the head and about .080 off the deck. KB167 piston .004-.006 below deck with .028 head gasket.

Pushrods are 7.060 long. The custom pushrod set was around $200.

Also, one of the heads, I had to elongate the holes where it passes thru the head. It was hitting same place as yours. Precision machining, casting, was not a priority for dodge way back then. Not impressed.

I have to either elongate the holes on my intake manifold or have it machined .030 per side due to misalignment on intake bolts.

If the threaded bolt holes are low (alignment) in the intake manifold holes, your heads or block,or both have been machined like mine is.

If your intake was machined as well, there won't be a misalignment, a stock manifold would reveal the truth.
Click to expand...
.080 off the deck and still .004 to .006 below deck with the kb167's?
 
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