stamped steel LA rocker arms

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str12-340

str12-340

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Just a reality check - are all stock stamped steel rockers for LA 318s and 340s interchangeable?
 
Supposed to be a heavier stamping in the 340/360 but that was debunked once. But they are the same dimensions.
 
I was culling through my stock of stamped rocker arms yesterday, looking for a set to clear the 1.5" O/D springs on my 360. Some are ground for clearance, I always assumed bcause 340/360 springs are larger diameter. Also, some have a more pronounced "detent" where the spring/retainer would be. I also have some of the supposed HD rockers, which seem to be stamped LH/RH vs. LT/RT, and I've found a weight difference of 15-20 grams. Again, this is all based on what I've found with the ones I have.

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I know that Direct Connection offered heavy duty stamped rockers - I have a set on one of my engines, but the overall dimensions are the same, which is the question... this is on a 318 street engine and I wanted to make sure that any of the stamped rockers that I have around would fit. Has anyone ever see the pocket for the push rod fracture and break away?

The engine ran just fine, but when I went to replace a failed valve cover gasket, there was the top of the pushrod visible through the rocker. It never pushed through the rocker and the tip of the pushrod doesn't seem damaged at all. The pocket just fractured all the way around including splitting the oil hole - not worn through.
 
Back when the 340 was new we broke plenty right at that spot
even with stock spring pressure.

I do believe the 340 rockers were heavier duty from what I remember
back them.
 
I had a pushrod go right through the rocker once. Popped the top right off the pocket, it landed in the valve side of the arm. 470-something lift, not a lot of spring pressure, just cruising down the freeway.
 
Where the heck is Winock, WA ??? - I even tried googling it with no success
 
str12-340 said:
I know that Direct Connection offered heavy duty stamped rockers - I have a set on one of my engines, but the overall dimensions are the same, which is the question... this is on a 318 street engine and I wanted to make sure that any of the stamped rockers that I have around would fit. Has anyone ever see the pocket for the push rod fracture and break away?
Click to expand...
yeah, the overall dimensions are the same.

as long as you're not concerned with the 340/360 "notch" to clear big springs (which i'm guessing no), then go on ahead and ship it.

and yeah, i've seen the pocket/cup tear/fracture and pull away. stock 2bbl 360 no less!
 
First racecar motor I built,340, dc 284-484 cam, keep pushing pushrods through the arms. Went to salvage yard and they had a 273 with adjustable rockers. Set of pushrods and I never had that problem again with that motor.
 
It seems to me that you'd wanna tailor the rocker arms used to the cam you have, but also take into account the heads you're using.

I'll be using ported 'O' heads on my 340 and, as far as I can tell, they're the 340/360 stock pieces.

That said, if the 273 pieces work better for your particular build, by all means, go for it.
 
Yes, there were heavier gauge rockers avail, I also have a set.

I punched the pushrod thru a few rockers, usually on a missed shift, the piston would spank a valve, witness mark on piston confirmed.
Carried spare rockers in glove box beside the spare ballast resistor.
 
Inertia said:
Yes, there were heavier gauge rockers avail, I also have a set.

I punched the pushrod thru a few rockers, usually on a missed shift, the piston would spank a valve, witness mark on piston confirmed.
Carried spare rockers in glove box beside the spare ballast resistor.
Click to expand...
Any recommendations for a warm 340?
 
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