The Stovebolt Site Forums The Shop Area Engine Shop 235 Mystery Rocker Numbers

I just scored some "new" rockers and shaft for my '53 235 and started to swap them out when I notice a discrepancy between the numbers the manual says I should be seeing and the numbers on my original rockers and replacement rockers... Here's a chart. First two columns are from the 48-51 shop manual ( http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0611.htm ) The third column is what I pulled off the truck, and the fourth is the new ones.

+------------+-------------------+-------------+---------------+------------------+
| Rocker···· | 216 & (48-49) 235 | (50-51) 235 | Off the truck | New Replacements |
+------------+-------------------+-------------+---------------+------------------+
| LH Exhaust | 1················ | 9·········· | 7············ | 7················|
+------------+-------------------+-------------+---------------+------------------+
| RH Exhaust | 2················ | 0·········· | 8············ | 8················|
+------------+-------------------+-------------+---------------+------------------+
| LH Intake· | 5················ | 3·········· | 1············ | 5················|
+------------+-------------------+-------------+---------------+------------------+
| RH Intake· | 6················ | 4·········· | 2············ | 6················|
+------------+-------------------+-------------+---------------+------------------+


(Note: 1954 Manual ( http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0611.html ) says all 235 are 9,0,3,4, while 261 are 1,2,5,6 -- which seems to indicate we should be rocking 9,0,3,4 for most 235's starting in 1950...)

Things currently work fine works fine with the rockers labeled 7,8,1,2,. I double checked and NO, the #1 off the truck is NOT an LH Exaust, it is most definitely a LH Intake.

The NEW rockers (7,8,5,6) look identical to the OLD ones (7,8,1,2)**, and both the new and old rockers have center oil grooves.

In the "Master Parts Catalog" ( http://chevy.oldcarmanualproject.com/1929_57chevyparts/57cmpc0140.htm ) it seems to indicate 7,8,5,6 covers everything from 50-57...

So here are the questions:

1. Any idea where the 7812 rockers might have come from? (I have no idea the history of rebuilds on this engine)
2. Do 1,2 correlate to any year's intake rockers, or are they ALWAYS exhaust?
3. Should I go with the Master Parts Catalog numbers and quit overthinking it?

Love a good mystery...

**I'll pull out the calipers tomorrow to verify the measurements.

Pre68 Dave is the wizard with rocker weirdness, and would be a better authority to weigh in here.

However, here’s a couple things I’ve learned through my own experience:

1). Having a hodgepodge of different rockers is common.

2) I don’t know why the different part numbers would matter as long as:

A. Intake and exhaust and LH/RH configurations are all placed in the right spot.
B. All the rockers are truly for a 235 and not mixed with 216 rockers or some such thing.
C. Oil groove is the same and set up to match the kind of rocker shaft connector you have (see Pre68 Dave’s website)

Addendum:

I think 1953 may have been a bit of an oddball engine (depending what type you have). That might be a factor here.

I agree, Pre ‘68 Dave is the authority on this subject. Here is a [LINK] to his website. You’ll see an article “235 Rocker Oiling” that you may find interesting.

I never tried to document all the subtle changes Chevrolet made through the years, but there were a few. Any time a change was made they got a new number.
Chevrolet experimented with the location of the vent hole, they also increased the hight of the backbone of the rocker as time went buy.
If the correct internal groove is used, and they contact the valve in the center, that is all I was ever concerned with.

"If the shoe fits- - - - -wear it!"

If the part fits- - - - -use it!

Jerry

That was my initial thought, but then I thought I should check with those who spent a lot more time thinking about these thoughts than I've thunk. Thanks!