Rockers and rocker shafts 340

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jcmeyer5

jcmeyer5

Token Ford Guy
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So getting ready to do the heads. Hopefully just a general cleanup and painting. First thing I noticed was how loose the rockers are on the shaft. The bored in the rockers are a lot larger than the shafts... by like 1/8”. Is that normal? No spacers or shims between them.

I’ll take them apart tonight.
 
If they are stamped steel rocker arms, preload keeps them tight.
 
Yes, they are the stamped stock ones. I am not comfortable with that though. Its extremely sloppy and uncontrolled.

Probably look into some sort of bushed rockers. I am fully against Pro-Comp, but they do have a nice (looking) set of bushed rockers
 
Worked fine on millions of engines. If its just a street engine I wouldnt worry about it. The biggest flaw with the stamped rockers is they are thin in the pushrod cup. Seen them punch through on several occasions.
Mopar used to sell replacements that were supposed to be thicker in the pushrod cup. Not sure if they still sell them.
 
As I’m looking at them more, I don’t think they are even correct for a 340. Don’t 340 have machined pockets for the springs? I’ll get some pictures.
 
jcmeyer5 said:
As I’m looking at them more, I don’t think they are even correct for a 340. Don’t 340 have machined pockets for the springs? I’ll get some pictures.
Click to expand...

You are correct about the machined pockets found on the factory 340 rocker arms.
This was done to add clearance due to the larger diameter springs that the 340's had.
Here is a picture of a original set of rocker 340 rocker arms and shafts that I have.
The red arrow points to one of the arms where the spring clearancing was done.

340 Rocker Arms.JPG
 
So I went out and grabbed a couple pictures. First is the rocker. Someone ground on it, but it isn’t anything like @694spd is showing. It also looks like it was still contacting the valve spring retainer. Second one is the exhaust valve on either #2 or #7. It looks... smooshed.

0415A402-ED9D-4729-8DFD-F42DA9442834.jpeg


D7CA2723-7530-43FF-8F74-EDB8696FB8F1.jpeg
 
Also, I see what you were saying about the preload taking up the slack in the rockers. It seems they designed the rockers this way... which makes sense when you compare them to other similar stamped steel offerings from Ford
 
Those springs look like they are too large. The diameter of a stock 340 spring is ~1.500''. The diameter of the stock retainer is 1.375".
 
Here is a pic of the bone stock 340 engine from my 69 Dart. You can see the difference between the retainers and the spring OD's

100_3231.JPG
 
You learn something new every day. I have 5 340's and did not know the rockers had a cutout on them.
 
Cut outs are generous. If mine are authentic, it’s likely someone with a hand grinder sent a few seconds ripping away some material
 
pt70 said:
Those springs look like they are too large. The diameter of a stock 340 spring is ~1.500''. The diameter of the stock retainer is 1.375".
Click to expand...

So I brought one of the springs and retainers to work with me today. The spring OD was 1.48", while the retainer was 1.33". That seems to be correct. Shim under the spring was 0.0625", or 1/16"
 
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