Custom push rod length checker for small block

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dibbons

dibbons

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I am arranging to have a custom adjustable pushrod length checker fabricated for me by the Smith Brothers in Redmond, Oregon. I will be using factory 1965 273 adjustable rocker arms and hydraulic (Lunati) cam lifters. I don't have access to any factory 273 pushrods or rocker arms this week because I am still on an extended road trip. Is anyone available to take any measurements for me? What is the diameter of the cup and ball of factory 273 pushrods and adjustable rocker arms? What is the factory length/diameter of 273 and 340 pushrods? Thank you!

P.S. I will probably order two adjustable length checkers for this application. If anyone is interested, we can probably make arrangements to make the same thing for you (or I can lend out my spare to those in future need).

Here is the message I need to answer:
"As far as making an adjustable length checker for you I will need to know what size cup and ball ends you need, also they have about .500 of range for checking so if you have a rough idea of the length you might be at."

273ra.jpg
 
I bought one when I did mine but for a solid lifter cam. The replacement lifters aren't always the same dimensions as the stockers. Replace the valves and or grind the valves, shave the heads or deck the block and you have "tolerance stacking" and will need a checker pushrod to get the proper length ones. Hydraulics are a little more forgiving because of the pre-load. You want to make sure the rockers "sweep" the valve stem properly during their travel. You may also need to shim the rocker shafts "up" to get to where you need.
 
I got a pair of checkers from PRW when I bought their roller rockers , I was surprised they were actually 2 complete units instead of just providing the 2 different ends for 1 unit .they sell them pretty cheap , probably cheaper than a custom build .
Just searched their site and they want 23.95 for them , they are for the cup style adjuster which is what you want , the Mopar ball type adjusters move the pivot point down too low for good pushrod geometry which is the other side of the valve tip sweep issue .
 
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cannucky said:
I got a pair of checkers from PRW when I bought their roller rockers , I was surprised they were actually 2 complete units instead of just providing the 2 different ends for 1 unit .they sell them pretty cheap , probably cheaper than a custom build .
Just searched their site and they want 23.95 for them , they are for the cup style adjuster which is what you want , the Mopar ball type adjusters move the pivot point down too low for good pushrod geometry which is the other side of the valve tip sweep issue .
Click to expand...


His rockers need the oil hole in a different location to oil cup adjusters. You just can't change from a ball to a cup adjuster.
 
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dibbons said:
OK Well, let me ask this then: how deep is the cup end of these Mopar ball and cup pushrods?
Click to expand...


Smith brothers should know how deep it is. There is Over All Length and Effective Length. Seems to me unless you are using adjusters that screw in from the bottom of the rocker the balls are all the same diameter so the cup radius should be pretty standard.
 
OK, some specs: 1964 273 2bbl pushrods hot off the solid lifters:
overall length 7 3/8 = 7.375 = 188mm (easier to read on a tape measure)
ball diameter .331"
cup depth .147

ball is not really a ball but more like a mushroom shape. some aftermarkets have a literal ball tacked on the end. SO effective length from tip of ball to base of cup is 7.228. So yeah, get a checker because everyone measures their pushrods a different way and tolerances do stack up.
 
Hey mate,
I converted my LA 318 to 273 adjustable drivetrain
I also used aftermarket alloy heads as well as having the block zero decked.
I found the Toyota Corolla 4k pushrods are an identical ball/cup size as the 273 but shorter.
Work perfectly in my engine with plenty of adjustment
 
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