What to do about rocker arms

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6dart9

6dart9

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I am just about done building my 73 340

Ok I bought the cam kit k20-223-3 which is the XE268H cam. It says in the spec card to use an adjustable valve train. Does this mean i need to find a set of 273 rocker arms and shafts? I am at the part in the build where I am ready to put the rocker arms on the heads and get ready drop it in. I must have overlooked this technicality when i was gathering parts for my build.

The part number it references for a comp cams rocker arm shaft and assembly is for a magnum motor so i was thinking maybe i didnt need it i could just use the non adj rockers.

Also on the comp cams instructions it says not to use the inner spring on the valves during the first break in. Is this just insurance in case the cam gets screwed under break in?

Any help or insight will be much appreciated
 
Use the stock non-adjustables with brass shim stock under the shafts to reduce the lifter preload. Bottom-tap the holes & use longer bolts on the shaft hold-downs. just a precaution to keep the stands from splitting.
 
george said:
Use the stock non-adjustables with brass shim stock under the shafts to reduce the lifter preload. Bottom-tap the holes & use longer bolts on the shaft hold-downs. just a precaution to keep the stands from splitting.
Click to expand...

What do you exactly mean about "brass shim stock"?
 
Put it together with the factory parts. That cam isn't so big that you'll need anything else. Just make sure that you're using valve springs that are designed for that cam and lift.
 
Yea I got the complete kit with cam springs lifters timing chain etc....
 
I'm in the same boat as you. Same cam. Same engine. 10.5 KB pistons, XE268, M1, TTI, 3000 stall, 3.91 Sure Grip. I have a set of stainless Chinese adjustables(new and I got them for nothing)but I am thinking of buying a set of 1.5 Huges adjustables. My problem is figuring out what pushrod length to get.
 
I would think the stamped rockers would be fine provided the pre load on the lifters is correct.
 
The stamped steel rockers work OK with that camshaft. It's right on the edge of requiring an adjustable IMO.

Lots of 284/484 and 508/509 hyd cammed engines running the stock stamped stuff.

Get proper length pushrods for lifter preload. Stockers will work, but, you may put a bunch of preload in the lifter.
 
I think if you look carefully, there are several "optional" parts for that cam. One is the adjustable rockers, another dual springs. You are fine to run the stock rockers. I would not shim anything... You could be messing up the valve train geometry. But instead, measure for the proper preload and get the pushrods that give it.
 
I have a friend running that same cam in his 318 with factory rockers,no shims no problems...
 
crackedback said:
The stamped steel rockers work OK with that camshaft. It's right on the edge of requiring an adjustable IMO.

Lots of 284/484 and 508/509 hyd cammed engines running the stock stamped stuff.

Get proper length pushrods for lifter preload. Stockers will work, but, you may put a bunch of preload in the lifter.
Click to expand...
I have new stock stamped rockers and pushrods(I put them in but even the rocker shaft wouldn't seat to the pedestals well..the pushrods seemed to long). But...don't the adjustable rollers rockers add HP? or is it just a marginal increase?
 
I ran stock pushrods and rockers on the next size up cam (274xe) for quite a while. I realize I was pushing it but I didn't have any trouble.

Definetly remove your inner springs for break-in. If not you'll most likely wipe out the cam.
 
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