Subtle Difference Between Ductile Iron Rocker Arms intake vs exhaust?

-
dibbons

dibbons

Well-Known Member
Joined
Nov 6, 2009
Messages
5,727
Reaction score
3,790
Location
La Paz, B.C.S., Mexico
I am finding the oil hole exiting the adjusting screw on the old factory 273 adjustable rocker arms comes in two diameters. They appear to be identical otherwise. I suspect the reason may be a difference between intake and exhaust rocker arms, but I have not seen that discussed anywhere that I know of. (also posting on FBBO)

rocker arm hole 1.JPG


rocker arm hole 2.JPG


rocker arm hole 3.JPG
 
I never noticed that on any I have but I never looked. I will look at a couple sets I have an see if they are like yours.
 
Poly had different rocker oiling between intake and exhaust. Those larger holes look huge! Ill check my 64's when i get home.
 
The set on my current 340 has different size holes like that.
Supposedly 273 rockers. They were rebushed by RAS a few years back. Not sure I paid attention at that time but I definately observed that last week when the covers were off.

I have a set of Crane rockers on a set of heads from my previous 340. I'll check them later this week...
 
PRH said:
Are they a different part number in the parts books?
Click to expand...
Good question.
Same p/n in the 1967 (digital version from mymopar)
upload_2020-7-20_22-36-46.png


So at least on mine, it could be something that Rocker Arm Specialties does.
 
Two sets here, one set big holes and other set mixed with more small than big.

20200721_161216.jpg

I'd say whoever assembled the OP's set had too much time on their hands.
 
Those are not oil holes. Those holes are where the oil holes were drilled through the rockers from the factory. They didn't bother plugging them off, since the adjuster screws block them.
 
RustyRatRod said:
Those are not oil holes. Those holes are where the oil holes were drilled through the rockers from the factory. They didn't bother plugging them off, since the adjuster screws block them.
Click to expand...

All but the last sentence is correct.
Those holes need plugged.

Reworking the 273 Adjustable Rockers | For A Bodies Only Mopar Forum
Reworking the 273 Adjustable Rockers
 
Last edited:
my untouched 64 had all the same size. Cant tell if they are the big or small though. Leaning toward the larger ones.
 
i'd check my 340 with those rockers but someone stole the engine from the garage it was stored in
 
I just measured the pushrods in this 1965 273 which are exactly 7.5" (191 mm) and .3149" (8 mm) in diameter. The chart I found on the internet doesn't show that combination, but shows the '65 pushrods as slightly shorter. Measuring end to end (ball to end of cup) they are definitely 7.5", not the shorter 7.344 in the chart. The diameter agrees pretty close to my measurements .3149" (me) and .312" (chart).

pushrod specs.png
 
Jadaharabi said:
All but the last sentence is correct.
Those holes need plugged.

Reworking the 273 Adjustable Rockers | For A Bodies Only Mopar Forum
Reworking the 273 Adjustable Rockers
Click to expand...

I don't disagree.....but it's not incorrect....at least not that I've ever seen. I've never once seen those holes plugged, so as far as I know the factory never did.
 
You must log in or register to reply here.
-

Back
Top